A myth busted! For me anyway

[Plod]

G'Day all, in my search for greater knowledge, I started wondering about warming up and idling my Td5 in these chilly conditions we've been having lately.

I came across this article. Yes the initial question relates to busses, but the answer from a Detroit Diesel (The company) engineer as I read it relates to ALL diesel engines. It's lengthy, but enjoy.

Diesel engine idling, from an authority: Detroit Diesel

Detroit Diesel 6v92Bryan asks in a recent post on one of the bus boards, “How long should a diesel engine be warmed up before driving off?”

Among the many considered answers is Ed’s post with a great explanation about diesel idling in general, from someone who oughta know: Detroit Diesel’s Mike Meloche, Senior Reliabilt Sales Manager:

Your question ranks right up there with the most commonly asked questions we receive. It is also, at least in my opinion, the most commonly misunderstood aspect of the operating parameters of a diesel engine. The short answer is we have always recommended that if the engine is going to be idling, low idle, longer than five minutes, that it be shut off. The reasoning is a little more complicated but without getting into engineering 101 basically the following is the layman’s reasoning.

Diesel engines were designed to operate at peak efficiency running wide open. As there are no spark plugs, cylinder temp., obtained by compressing air in the compression cycle, is necessary to ignite the fuel. At low idle the cylinder temp. drops leading to incomplete combustion. This incomplete combustion leads to carbon build up on the valves, in the oil (crankcase), on the fire deck of the head and the dome of the piston along with fire rings on the piston. Engine “slobbering”, what appears to be oil, out of the air box drains and the exhaust are other side effects. As worn oil control rings will also give you both of the last two items this is often cited as the cause of an engine “slobbering”. The irony is that the carbon build up in the oil will lead to worn oil control rings.

Now the reasons folks give for letting the engine idle - “I need to keep up cab heat / AC in the winter / summer.” If you are going to be away for less than 10 minutes the engine will keep more heat being shut off than idling for that amount of time. The AC unit will not maintain temp at low idle. “Truckers all leave their rigs running while at a truck stop.” They aren’t paying for the fuel or the repairs. “When you’ve been running all day you need to let the engine “cool” down for at least ten minutes before shutting it down.” Simply not true!!

Can I get a chorus? If the engine is going to be idling, low idle, longer than five minutes, shut it off.

Oh by the way, on the how long before I drive off question? I think Andy came up with the best commonsense answer:

“Let it run for 30 sec to a minute to insure that the entire engine has oil pressure then pull out easy. I like to take it pretty easy until the temp gauge starts moving then drive in your normal manner.”

Clarke adds the following as always well-written everything-you-wanted-to-know about idling:

Don’t idle engines.

By Clarke Echols on February 12, 2006:

The worst thing you can do to any engine is let it sit and idle.

For gasoline engines (cars, pickups, light trucks), start it. If the weather’s cold, let it idle briefly until it is firing on all cylinders, then ease out into the street and let it warm up while working. Idling a cold engine in cold (Rocky Mountain or Northern States areas) weather until it warms up is murder on the insides. It casues high acid build-up in the oil, and generally destructive. A fuel-injected gas engine will start immediately, even in cold weather (down to zero or ten below — minus 40 might be a bit tougher). As soon as it’s running, get going. Don’t idle. If mama wants a warm car, you may have to compromise, but it’s idling that contributes to pollution because there’s not enough exhaust to get the catalytic converter running properly.

Even a warm/hot engine is damaged by idling. One minute at idle is as bad on most engines as two miles of driving at 60 mph on the interstate, whether gasoline- or diesel-powered.

Diesels pull a full gulp of air on every intake stroke. They have no throttle butterfly like gas engines to restrict air flow for idling. They just change the amount of fuel being fed into the injectors to control speed/torque. If the engine isn’t working hard, it gets a smidgen of fuel, not enough to maintain block temperature, and the intake air is like a big blast of refrigerating (cool) air, especially if the turbo isn’t spinning at full compression. Thus the engine cools to below its design operating temperature and you get the high wear factors again.

Idling wastes fuel. It takes about 0.3-0.4 pounds of fuel per hour to produce on HP of output from a diesel. There are 7 pounds of diesel in a gallon. It takes at least 10-15 HP or more to idle a diesel, depending on size, including alternator, compressor, etc. At 0.3 lb/hr, 10 HP = 1/2 gallon of fuel per hour; 20 HP = 1 gallon per hour. At $3/gallon, that’s a lot of bread to be blowing out the stack for no good reason.

If you’ve been pulling hard down the highway and pull in for a stop, let the turbo cool down, but in most situations, by the time you get from the exit ramp through the traffic signals and into a parking spot, you’ve already burned of 1-3 minutes which is adequate for turbo cooling, so just shut down the engine. When you restart, it will be fully warm and ready to roll immediately, assuming you didn’t park for an extended time of hours, even in cold weather. Especially in cold weather, you really knock the temp down on an idling engine.

So start it, get the air tanks up to an adequate pressure (some air bags don’t air up until a minimum-pressure valve opens at 90 pounds or some similar level), then ease it out. As long as you’re not blowing air off of the brakes faster than the compressor can air the tanks up, you should be fine, and the tanks will fill faster as you are driving down the road at the start of the trip.

Once it’s warming up, don’t be afraid to lean on the throttle if you’re so inclined. But you’ll save fuel if you keep your foot out of it.

If you’re hot-footing it and you’re blowing black smoke, lay off. As soon as it starts smoking, that says it’s getting more fuel than it can burn, and you’re just wasting diesel. You won’t go any faster, because the engine’s already at its peak.

For best engine life, don’t idle, and treat it with respect while not warmed up, and again after it’s fully warmed up as well.

[Signal1]

Well I'll be...:eek: Thanks Plod

[jik22]

That's fascinating....thanks for posting.

[ddkemp]

Thats an amazing story.Land Rover specialist,( or so they promote have always said,( let the car idle for about 1 min after a hiwayrun, to let the Turbo cool down, and on start up, let it warm up for optimum operation in cool conditions.

Who do you listen to these days, or is just gut feel?

Dave Kemp
S11 Disco TD5
S1 V8 SE Disco
S111 SWB 2.25 petrol

[isuzurover]

It does say to let the engine idle for 30 sec to 1 min when cold. Often it takes that long for oil to be pumped up to the valve train.

[Rayngie]

The hand book in my Discovery says not to idle it to warm up, so i never have, if Landrover say not to, i'm happy for that...

[wovenrovings]

I have seen diesel engines operated in switzerland without warm up in very cold conditions and they had no problems and excellent engine life (a little less dust in the air there too). Also it is general pratice to turn the engine off at traffic lights there.

WR.

[rick130]

What Ben said.

You let them idle enough to stabilise oil pressure, then away.

Idling while warm is bad news too. A bloke I know that runs a fleet only allows 2-2.5 minutes idling max for any of his rigs, or the drivers face dismissal !

[cookiesa]

A bit concerning coming from the same person

"So start it, get the air tanks up to an adequate pressure (some air bags don’t air up until a minimum-pressure valve opens at 90 pounds or some similar level), then ease it out. As long as you’re not blowing air off of the brakes faster than the compressor can air the tanks up, you should be fine, and the tanks will fill faster as you are driving down the road at the start of the trip."

There is a lot more said about allowing turbo's to cool down for anywhere between a couple of seconds and a few minutes depending on how hard the engine/turbo has been working.

It would be interesting to hear from someone in the know how the wear of idling versus the wear of continual stop/starts compares, I'd put money on that being more damaging than the idling.
An interesting read though

[QSDT]

Thanks 4 finding that info very informative.

[Quiggers]

Well, I'll be buttered on both sides...

Looks like my warm up regime has gone out the window...

GQ

[Cap]

ohh crap, here I am idling the engine away for 5minutes (yes, the wife takes a long time to come out to the car) thinking its all good :( Hmm, so looks like ill have to cut that habit.

[mcrover]

Most of my machines on the golf course are Diesel, some NA and 3 are Turbo'd and as a rule of thumb, I tell the guys to let it fast idle for about 20 to 30 seconds until it is running nice and then full throttle (most other than 1 tractor are Hydraustaic) and drive out.

I have heard this before but I have also heard arguments for Idling but knowing how a Diesel works and the fact that the amount of air that goes into a NA diesel doesnt change per stroke a significant amount it wouldnt surprise me if it were true but may not be a detrimental as they make out.

Turbo engines are a little different as at idle the turbo is doing nothing but when engine revs increase, so does intake presure so the amount of air in increased alowing more fuel to be pumped in to produce more power so I would believe that Idleing a Turbo motor for more than 5 mins would be quite detrimental as the bigger the bang at optimum revs the more heat that is produced and the morethe engine would cool down in the process.

My machines when they return at smoko have the revs dropped as they come past the back of the shed and then the lower them more to enter the shed, then idle them for 10 to 30 seconds depending on if it is turbo and how hot it is and then shut it down.

After 30mins smoko, all the machines are still pretty much at operating temp when restarted so I dont see the problem with that.

I have seen some very glazed Ford and perkins diesels over the years from excessive idleing in tractors as they would have a flat battery so they would roll start it in the morning and not turn it off until they left.

All you see is pure white smoke pooring out of the exaust of cold unburned fuel and it doesnt clear for ages in which time they normally think they should be more gentle and not rev the engine which makes it worse.

I used to just put them on full throttle for a luch break or 2 and it would clear, then fix the starting problem but some of them needed a decoke and hone to bring them back to life.

[George130]

:eek:
Well I'm be. I have tended not to switch off when out bush in convoy. If we all stop at an obstacle I let it run with all fans on full to suck as much heat out as I can. Thought this would be good for the gearbox and engine during summer. Guess I will start to turn it off quicker.

It's a shame you always get told the opposite.

[solmanic]

I think the key term to understand here is "low idle" which is different to the engine speed when warming up (usually a high-idle). I usually warm my engine up at about 2000 - 2500 RPM. That way the oil is circulated and things heat up relatively quickly but with no stress to the engine. I then pull out and maintain about 2500 RPM down the hill (I live on top of one) in a slightly lower gear (3rd usually) to get the oil moving around in the gearbox.

Essentially what I read was that letting the engine idle on tick-over is bad, but idling at higher revs (for warming up or keeping air etc. running) is not such a problem - just maybe a waste of fuel.

[UncleHo]

G'day Folks :)

That is interesting, but aren't Detroit Diesels 2 stroke?? the same as Cummins? if so they are a whole different kettle of fish to a 4 stroke diesel and particularly an older British /European Type that is why they fit Radiator Blinds, as the principal of a diesel is Compression Ignition, so the hotter the Block is, the better the ignition, or that was what I was taught, that was before the high speed 2 stroke diesels appeared on the market, the reason a diesel is left running during short stops, is that it is often more damaging to restart (oil drained back to sump) and more expensive, use of starter than to leave it running as diesel use is minimal.

cheers

[mcrover]

G'day Folks :)

That is interesting, but aren't Detroit Diesels 2 stroke?? the same as Cummins? if so they are a whole different kettle of fish to a 4 stroke diesel and particularly an older British /European Type that is why they fit Radiator Blinds, as the principal of a diesel is Compression Ignition, so the hotter the Block is, the better the ignition, or that was what I was taught, that was before the high speed 2 stroke diesels appeared on the market, the reason a diesel is left running during short stops, is that it is often more damaging to restart (oil drained back to sump) and more expensive, use of starter than to leave it running as diesel use is minimal.

cheers

Detroit and cummins dont only make 2 stroke Diesels but that is what they are famous for.

At idle, my understanding of that artical is that the cold air inducted into the engine being the same amount as at higher revs, cools the engine from the inside out as a diesel engines speed and torque is determined by the amount of fuel that is injected into the cylinder or combustion chamber.

[mcrover]

I think the key term to understand here is "low idle" which is different to the engine speed when warming up (usually a high-idle). I usually warm my engine up at about 2000 - 2500 RPM. That way the oil is circulated and things heat up relatively quickly but with no stress to the engine. I then pull out and maintain about 2500 RPM down the hill (I live on top of one) in a slightly lower gear (3rd usually) to get the oil moving around in the gearbox.

Essentially what I read was that letting the engine idle on tick-over is bad, but idling at higher revs (for warming up or keeping air etc. running) is not such a problem - just maybe a waste of fuel.

I think your about right with the high idle thing and some auto trans cars wont go into top gear or lock up until the engine and/or trans are at a cirtain temperature so why not do that, it couldnt hurt.

[lewy]

Beware of shutting turbocharged engines off immediately after high revs. Remember the turbo is spinning very fast and is lubricated by oil pressure. Shutting engine down equals nil oil pressure to turbo bearings.

[101RRS]

In canberra we have very cold mornings and I have never allowed my engine to warm before driving off - but I do not load up or rev up the engine either when driving until the engine has got to operating temperature.

People sometimes have said that u don't have to let the turbo spool down when u have driven around town but need too after a long trip. I disagree - on a long trip my engine is only doing 2700 rpm at 110 yet around town or even driving up the hill to my house the engine often is up around 4000rpm when acceralerating up and down when driving. When switching off I just let the engine settle back to idle then switch off. If I know the engine is abnormally hot I might let it idle just a bit longer. My car has covered over 220,000 and the engine is still running well with no abnormal wear on the turbo, no oil in the induction system and no noticeable oil usage between oil changes so my process of not idling unnessarily at startup and shutdown must be doing something right.

Garry

[cartm58]

your cooling the turbo not the diesel engine thats why they have a cool down before you switch off advice after sustained highway driving

[aaron.miller]

A quick question on all this,
If you drive up a hill in traffic at night and sit on about 3000rpm, mines a auto by the way if you look in your rear view mirror can you see smoke in the lights of the trailing car?? I do. That being said if i do the same hill in the day time i cant see any smoke so could it be just particles showing up in the lights??

Aaron

[Zute]

Yeah Aron, I get the same thing. Only real way to tell is to follow in another car.
Back to topic. Ive often fitted mechanical oil gauges to some of my cars and they give you a better idea, of how long it can take for oil to get to every part of the engine. The needle will flick slightly as oil moves into oil galleries and as air is displaced. Some times this can be up to 2minutes.
I think 2minutes idle when cold is still best practise.
We've got a turbo timer, which is set for 1 minute. Some times it feels way longer. If it hasn't turned off and I need to drive off again, you can just turn the key to on and keep going.
But you need to turn off the timer when re priming the fuel system.:angel:learnt that the hard way.

[rick130]

G'day Folks :)

That is interesting, but aren't Detroit Diesels 2 stroke?? the same as Cummins? <snip>

cheers

geez, not for over twenty years !

The DD60 series engine was the first electronically controlled, unit injector modern 4 stroke diesel nearly twenty years ago. Way before the Euro engine builders. I think these blokes might know what they are talking about ;)




Idling is bad for diesels, contrary to all the old school advice. It primarily leads to bore glazing and cylinder wear.

[JDNSW]

Idling is bad for diesels, contrary to all the old school advice. It primarily leads to bore glazing and cylinder wear.

Don't know about old school!

"The injectors of any diesel engine will quickly become fouled if the engine is allowed to idle at low speed. If the tractor is not working shut it off...." - Operator's Handbook, Chamberlain Champion 306, 1968.

[catch-22]

At idle, my understanding of that artical is that the cold air inducted into the engine being the same amount as at higher revs, cools the engine from the inside out as a diesel engines speed and torque is determined by the amount of fuel that is injected into the cylinder or combustion chamber.

turbo boost would change the amount of air being drawn/forced in to the engine...

[disco2hse]

That is what I have always done with the Disco since I got it. The manual is very clear about not running the engine to warm it up, but to wait until the oil lights are off before moving off. And on stopping, to let the engine run for a few minutes before shutting off if it has been pulling a load or running on the highway.

When I did a course with a LR trained 4WD instructor that is also what he said and every time we stopped to open a gate or do something outside the vehicle he repeated his mantra "Secure the vehicle and shut it off, get out then shut all the doors".

[cookiesa]

Were crossing over two very different engines here too with these generalisations.

Big commercial diesels such as Detroit and Cummins have much lower operating ranges than what our "high performance" (These things are relative!) 4/5 cyl turbo intercooled diesels. They don't work at anywhere near the rev range we subject ours too.

The more modern the turbo design the more likely you are to get away with a quicker shutdown. A lot of the bearing failures attributed to the earlier turbo's was because they relied on oil cooling. If you shut your engine down while the turbo was still red hot the oil boiled off and at startup there was very little lubrication, over time this took it's toll on bearings.

To overcome this water cooling was added. The main advantage of water cooling is that even after you shut off the engine the water still circulates through natural convection so continues to pull the heat away (although obvioulsy not as effectively as if you had allowed the engine to idle for a couple of minutes)

[Frenchie]

I was also told that problems arose with mineral oil which would carbonise on hot turbo bearings when the motor was shut off too quickly, but with synthetic oil it doesn't do that.

I still idle for 20-30 sec normally and a couple of minutes after a highway run though, can't hurt.

[up2nogood]

Idle down time for turbos has much to do with their operating speed.

As you know, a turbos oil supply comes from the engine. Now if the engine has copped a flogging, the turbo will be hot and the compressor wheel will be rotating at high speed.

If they're still spinning at full tilt when the engine is shut off you will have a hot turbo with no oil supply.

[scrambler]

Similar to what someone posted above, when my Dad had a work Toyo TD 100 series the handbook, and confirmed by the mechanic, advice was that unless you were absolutely flogging the vehicle in the couple of minutes before shutting down there was no need to idle the turbo.

[PhilipA]

I bought a charade Turbo at auction in Sydney in 1991.
Oil was dirty , but drove it home which was in Wyagdon St North Sydney right near the Falcon St exit of the expressway. to get there had to go up a BIG hill.
Turned the engine off ( this is the FIRST DRIVE). Next time I started it, the turbo screamed. I fixed it by soakingthe bearing assembly in carbon tetrachloride for a while( to soften the carbon) but the bearing was damaged.
In the end the only solution was a reconditioned turbo. So yes oil is the key to turbo longevity.
I always used synthetic from then on, and even though it didn't fix the tired turbo, the new one lasted until I sold the car many years and 200K later. I always knew when the wastegate was jammed as my wife would come in and say "Gee the Charade is going well "
One thing I learned from 3 turbo cars (Charade , Cordia, Porsche) is that once they get noisy the only fix is to reco them.
Regards Philip A

[B92 8NW]

And this is when an EGT is handy. Why guesstimate the time for the turbo to cool down when you don't know how hot it actually is? I let mine idle until its at around 150-200 degrees. I have a turbo timer but never use it. My EGT is also PIR controller, so technically I could wire it to shut the engine down through the turbo timer when the temperature hits a preset value.

[lewy]

This should scare some.
my experience with idling diesels.i have operated diesel machines from the middle sixties and have seen sixtys and earlier cat etc bulldozers that were what we called glazed up.this means that the bore was to for want of a better word “polished” this occurred when the engine was idled for long periods.This resulted in excessive oil usage .we used to cure this by adding a teaspoon of bon amy or ajax powder down each injector holeto grind away the bore and rough it up.This usually resulted in fixing the excessive oil consumption and if it didn’t we rebuilt the motor.Do not do this to a modern engine

[Ace]

So does this mean having a turbo timer with a 5min setting is actually doing more damage than good?

I let mine idle for 30secs to a minute when i get home to let the turbo cool down but thats it, if i have to wait at the bottom of the drive while stacey gets out and opens the gate or i have to stop to open the gate, drive through and then get back out to shut it i dont bother, i figure thats the idle time i would have given it in the carport. i start the car in the morning on cold mornings and then go down to the gate, open it and come back to the car and drive it out then shut it and drive to work. Matt

[Bigbjorn]

A hydraulic accumulator like the "Nical Turbo-saver" is more sensible than an idle shut-down timer. Turbo problems arise from shutting down whilst the turbo is still spinning at very high rpm's when the oil supply is cut off. The accumulator pushes accumulated engine oil back through the turbo bearings after shut down. Fairly common in heavy trucks of US parentage. I have made a couple (years ago) using loader crowd cylinders. Not hard for a fitter-machinist to work out.

[rick130]

And this is when an EGT is handy. Why guesstimate the time for the turbo to cool down when you don't know how hot it actually is? I let mine idle until its at around 150-200 degrees. I have a turbo timer but never use it. My EGT is also PIR controller, so technically I could wire it to shut the engine down through the turbo timer when the temperature hits a preset value.


exactly, although I use under 270*.
If I used any lower, I'd be sitting there for a week.........

[tombraider]

We all seem to know whats best for our engines...

Yet LRs own manual for TD5 engines states:

Drive away once started and Oil light has extinguised... Do not rev or load until in normal temperature zone.

It also states... Idle for 10 seconds before shutting down...

I drive Lara to work at 6.00am and its -0 to -2c at the moment.
She's "glowed up" and once the indicator goes out its crank over...
I then fit my belt and then drive straight to work...

Lara also has a TTimer and it's set to 10 seconds. If the vehicle has been worked (low range 4000rpm etc) for extended time I allow it to run out to 20 seconds ;)

The Bon Amy trick was a TSB from LR for the earlier TDI engines too....
They had a batch that werent bedding in properly.

For those that are high idling an engine to 'lube and warm it' is just wasting engine life and fuel...
Your engine isnt made/designed to rev without load. Your not doing it any favours... Just like using "angel gear" to decend hills.... Its murder on the input bearings on the gearbox.

[Jamo]

Thanks for the info Plod.

The TDV6 is the same as for the TD5. Don't idle before driving off and run the engine for only 10sec before switching off after heavy loading of the engine.

The engine ECU won't actually let you put heavy loads on the engine until it's ready for it. ie. put your foot down straight off and she'll just ease off slowly! This only last for a short time.

[Ace]

Thanks for the info Plod.

The TDV6 is the same as for the TD5. Don't idle before driving off and run the engine for only 10sec before switching off after heavy loading of the engine.

The engine ECU won't actually let you put heavy loads on the engine until it's ready for it. ie. put your foot down straight off and she'll just ease off slowly! This only last for a short time.


now that is a nifty feature, makes buying a used D3 better, knowing the engine hast bee flogged by thew previous owner when cold.

[paulthepilot_5]

We all seem to know whats best for our engines...

Yet LRs own manual for TD5 engines states:

Drive away once started and Oil light has extinguised... Do not rev or load until in normal temperature zone.

It also states... Idle for 10 seconds before shutting down...

I drive Lara to work at 6.00am and its -0 to -2c at the moment.
She's "glowed up" and once the indicator goes out its crank over...
I then fit my belt and then drive straight to work...

Lara also has a TTimer and it's set to 10 seconds. If the vehicle has been worked (low range 4000rpm etc) for extended time I allow it to run out to 20 seconds ;)

The Bon Amy trick was a TSB from LR for the earlier TDI engines too....
They had a batch that werent bedding in properly.

For those that are high idling an engine to 'lube and warm it' is just wasting engine life and fuel...
Your engine isnt made/designed to rev without load. Your not doing it any favours... Just like using "angel gear" to decend hills.... Its murder on the input bearings on the gearbox.

"angel gear" Please Explain!

[100I]

neutral

[Bigbjorn]

"angel gear" Please Explain!

Also called Mexican overdrive. Coasting down steep grades in neutral. Much practised by truckies of my generation. Driving with the angels. A compensatory measure for lack of horsepower in the days when linehaul prime movers were lucky to have 250 hp. Up the hill at 5kph and float down at 140. And also a life & engine saving measure when said prime movers had minimal brakes. Also known as "floating". A practised floater on the right road could float for up to 22 kilometres on sections of the old New England Highway. Oft-times one would have to throw her out and float when the braking systems of the time gave in, and hang on and hope, or, if travelling slow enough, jump out and leave her. Try losing all brakes downhill on the Toowoomba Toll Bar and hanging on until well past Withcott. See what colour your face and underpants are after that. Happened to me with a Commer TS3 "Knocker" with a bogie trailer of wool ( illegal loading then).

[paulthepilot_5]

Ok, I had heard the term used by someone who used to drive centurion tanks! It was called out to the rest of the crew if they were going down hill and the thing didn't go into gear, In other words, Hold The F**k on! :o

[100I]

kerist, I wonder how tracks hold up at those speeds.
schmokin

[paulthepilot_5]

Yep, It would be a bit of a worry, if you were driving down hill in front of a centurion, an 80tonne block of steel on tracks is not going to stop too stop in a hurry :eek:

[mcrover]

I dont know about input shaft bearings life span but it is more than likly that coasting in neutral at those sort of speeds was called angel gear as that was where you would end up, with the angels (and not charlies angels) or in other words, would shorten the drivers life expectancy.

I know for a fact that a SIIa shorty can coast from halfway back from tolmie into mansfield as I have been in one that has done it and I can tell you it was not much fun as he didnt touch the brakes the whole way down.

[Blknight.aus]

my 2 c on this...

dont idle your engine on startup let it get oil pressure, count to 10 then drive off... shut downs can vary.....

If youve been working the box off of it it will be hot even NA engines will benefit from a 2-3 minute cool down to "normalise" the engines themal loading. the reason is simple, if you shut down a freshly hard worked cast iron engine it has a lot of latent heat in parts of it (piston heads, the sides of the block, con rods manifolds) that dont have access to the "wet" cooling system. When you shut down you stop the coolant circulating and stop the airflow in the engine bay, as the parts of the block pass the stored heat back into the cooling system its possable to have the engine overheat while its shutdown.. The same holds true for an alloy engine but the times are shorter as aluminium is a much better conductor of heat. Turbo engines follow the same rule but also have the turbo to worry about for reasons that IMHO have been perfectly delt with already.

There are a few circumstances when you DO NOT shut down your engine for a prolonged holt. when its COLD... If your above the alpine line and its cold enough (below the minimum intifreze temp of your coolant) you dont shut down the engine for a prolonged halt. If the cooling system freezes you have to defrost it somehow before starting up or you will frell the engine.. In some cases if the battery is not preforming due to the cold and the block and air is cold enough a diesel wont create enough heat from compression to start itself which is why in places like canada cars are fitted with electric engine warmers.

[mcrover]

my 2 c on this...

dont idle your engine on startup let it get oil pressure, count to 10 then drive off... shut downs can vary.....

If youve been working the box off of it it will be hot even NA engines will benefit from a 2-3 minute cool down to "normalise" the engines themal loading. the reason is simple, if you shut down a freshly hard worked cast iron engine it has a lot of latent heat in parts of it (piston heads, the sides of the block, con rods manifolds) that dont have access to the "wet" cooling system. When you shut down you stop the coolant circulating and stop the airflow in the engine bay, as the parts of the block pass the stored heat back into the cooling system its possable to have the engine overheat while its shutdown.. The same holds true for an alloy engine but the times are shorter as aluminium is a much better conductor of heat. Turbo engines follow the same rule but also have the turbo to worry about for reasons that IMHO have been perfectly delt with already.

There are a few circumstances when you DO NOT shut down your engine for a prolonged holt. when its COLD... If your above the alpine line and its cold enough (below the minimum intifreze temp of your coolant) you dont shut down the engine for a prolonged halt. If the cooling system freezes you have to defrost it somehow before starting up or you will frell the engine.. In some cases if the battery is not preforming due to the cold and the block and air is cold enough a diesel wont create enough heat from compression to start itself which is why in places like canada cars are fitted with electric engine warmers.


I have seen while working on Mt Buller, busses and some 4wd's have snow shutters on their radiator intakes and aircleaners, like your typical Jap carbi aircleaner in the 80's, they would pick up air from around the exaust so the intake air was heated shortly after starting.

It makes sense to me now why they did it as it was one of those things that I thought was unnessesary and something that was cheap to add and could sway a sale to companies buying the vehicals for snow areas.

Interesting.

[JDNSW]

............

There are a few circumstances when you DO NOT shut down your engine for a prolonged holt. when its COLD... If your above the alpine line and its cold enough (below the minimum intifreze temp of your coolant) you dont shut down the engine for a prolonged halt. If the cooling system freezes you have to defrost it somehow before starting up or you will frell the engine.. In some cases if the battery is not preforming due to the cold and the block and air is cold enough a diesel wont create enough heat from compression to start itself which is why in places like canada cars are fitted with electric engine warmers.


When my brother was working in Antarctica forty years ago, when out on the ice they went for six months at a time without shutting the engine off except once a month for just long enough to change the oil. If it got cold they would never start it. But this is exceptional circumstances.

John

[p38arover]

I shall change my instructions to my daughter re idling tghe Disco.

Ron

[Capstan]

In very cold conditions, like bus tours through the Himalyas, they are known to leave the vehicles idling all night with a fire under the diesel tank to stop it turning to jelly. If the motor stops you have about 1 minute to get the hoses off so the coolant doesn't freeze, expand and crack the block.

This happened on a Top Deck tour once. Even the passenger's water bottles had frozen, they stalled the bus, probably from gluggy fuel and the block cracked.

[isuzurover]

You know how long most engines last in really cold places though...

In places like siberia, they mix up to 30% petrol in with the diesel. This is permitted by the manufacturers.

[BigJon]

I then fit my belt and then drive straight to work...



How do you keep your pants up until then? :eek::p

[Quiggers]

I stayed a night at Salina Utah a while back. Outside the motel (and truckstop) more than 100 rigs idled the night away; outside temp at 0600 the next day was minus 20, bleak and snowing...and windy and not fun....

I can only assume these drivers knew about diesel and diesel engines...and below freezing conditions.

GQ

[d2dave]

I was recently driving a Kenworth T404 SAR fitted with a Catapiller C15.
This truck being fairly new had all the owners manuals including Caterpillars manual for the engine.

The truck was fitted with a selectable turbo timer. The book said to let the engine idle for three minuets before shut down.

For start up it said to not rev above idle until full oil pressure is at the gauge and if this is not achived with in a few seconds to shut down the engine.

As for idling they say to not let the engine idle for more than five minuets or the turbo can suffer from lack of lubrication.

This truck, and I know that Western Stars also have this; When stationary you can use the cruise control to increase and hold the engine RPM to about 1600. This is if you need to leave truck running.

I know a driver who pulls over for a half hour power nap and on a hot day leaves the engine running at 1600 to keep his air con working.

As for angle gear, the reason it is bad for the gearbox is that the gear box has an oil pump driven by gearbox input which means engine revs.

This is the same as an early four speed Range Rover. The oil pump lubricates the gears where they are spinning on the main shaft.
So when the mainshaft is turning at road speed (the output shaft which is directly connected to the tailshaft) the oil pump being driven at idle speed does not supply enough oil to match the mainshaft speed.

This can easily be over come by raising engine revs when in angle gear, which is what I used to do with this truck going down a big hill until I lost my licence (126kph in a 100kph zone).

Dave.

[cookiesa]

There are other issue's when operating in sub zero temperatures, least of which is the driver not freezing to death. But there can also be serious issues with various other compnents freezing

[Zute]

Yes, air compressors need to keep running so air lines don't freeze.
New Volvo FH prime movers with I-shift will slip in to neutral and drop to idle at highway speeds when coasting. Than pick up the right gear and engine revs if speed drops or if speed increases above set speed. Kind of spooky at first. Haven't been able to tell if it saves much fuel though.

[wovenrovings]

The only reason they keep the engine running in super cold conditions is to keep everything warm. I was reading the other day about a unit they can install , some sort of heater and generator, that heats engine, cabin, load and provides power, and at the same time uses less fuel than idling the engine. Most european petrol cars will happily start in -20. Most diesels as well (as long as the fuel is not solidified).

[disco2hse]

Thanks for bouncing this up. It was good to read this thread again.

Aside from big engines and small engines, and really hot or cold conditions, when you're out on the tracks it just gets very tiresome when you have a couple of people whose engines continue to rattle when they should shut them down. Bird sounds are a lot more pleasant when you are in the middle of the bush.

Alan

[nzlandies]

In our club it is fine-able offence to leave it rattling.

In my td5 handbook I am sure it says start up and drive away quietly. Do not leave to idle cold.

cheers

[loanrangie]

The only reason they keep the engine running in super cold conditions is to keep everything warm. I was reading the other day about a unit they can install , some sort of heater and generator, that heats engine, cabin, load and provides power, and at the same time uses less fuel than idling the engine. Most european petrol cars will happily start in -20. Most diesels as well (as long as the fuel is not solidified).

These pre heaters are common in Europe and North Amercia, Kenlowe brand units are advertised in the UK LR mags.

[disco2hse]

In our club it is fine-able offence to leave it rattling.

In my td5 handbook I am sure it says start up and drive away quietly. Do not leave to idle cold.

cheers

Really? Which club is that. I think it might be worth mentioning to a few around here.

About the TD5, yes you are right. It does.

Alan

[Bigbjorn]

I still have a Drivers Handbook from one of my Detroit Diesels.

Quote" Warming up the Engine."

Naturally aspirated versions:- After the engine starts, run it at 1000 rpm and check the oil pressure gauge to be sure the engine is getting lubrication.

Turbocharged versions:- After starting a turbocharged engine, run it at low idle for two minutes to permit lubrication to flow to the turbocharger. Then run it a 1000 rpm and check oil pressure.

If the engine is maintaining oil pressure and the other systems that should be functioning at this point show normal on the instrument panel, the engine is ready to move the vehicle. If possible, avoid going to full throttle until engine coolant temperature reaches 140 F.(60C). The engine will come up to normal operating temperature shortly after you start driving. Unquote

Quote "Avoiding unnecessary or prolonged idling"

Idling the engine for long periods wastes fuel and may adversely affect engine life. Deposits of unburned fuel can form on the cylinder walls resulting in accelerated wear. When you leave the cab or plan to park for m,ore than a few minutes, shut the engine off. If idling can not be avoided due to the type of operation and the engine is to idle for a prolonged period, try to maintain at least 1000 rpm.

The temptation to idle the engine is strongest in cold weather when cab heat is a factor. Actually an idling engine cools down faster than if it is shutdown. You may find the cab heater, which relies on hot engine water, blowing cool air sooner than you might expect when the engine is left idling. Unquote

[Tank]

G'day Folks :)

That is interesting, but aren't Detroit Diesels 2 stroke?? the same as Cummins? if so they are a whole different kettle of fish to a 4 stroke diesel and particularly an older British /European Type that is why they fit Radiator Blinds, as the principal of a diesel is Compression Ignition, so the hotter the Block is, the better the ignition, or that was what I was taught, that was before the high speed 2 stroke diesels appeared on the market, the reason a diesel is left running during short stops, is that it is often more damaging to restart (oil drained back to sump) and more expensive, use of starter than to leave it running as diesel use is minimal.

cheers
Which Cummins engines are 2 strokes, have never seen one in a truck, I think you'll find that Cummins engines (Truck) are 4 stroke, Regards Frank.

[twitchy]

Diesel engines were designed to operate at peak efficiency running wide open.



My old man's mechanic always says drive a diesel like you hate it & it will run so much better.

Experiment= I borrowed the in laws Hilux. Father in law snails it everywhere & it ran like a pig when I got it. I ran it hard for 2 weeks (without flogging it) & the end result was a vehicle with better acceleration, better able to maintain highway speeds & used a little less fuel.

[AKW]

To the best of my knowledge cummins have never had a 2 stroke
truck engine.
A mate was running 3 trailer road train Sydney to Darwin and
cummins approived 1000 rpm idle with the a/c running.

My tdi 200 start back out of carport out the driveway &go
not over 2000 rpm till warm & very rearly over 2500.

Very interesting thread though.

Andrew

[disco2hse]

My old man's mechanic always says drive a diesel like you hate it & it will run so much better.

Experiment= I borrowed the in laws Hilux. Father in law snails it everywhere & it ran like a pig when I got it. I ran it hard for 2 weeks (without flogging it) & the end result was a vehicle with better acceleration, better able to maintain highway speeds & used a little less fuel.

It may be of course that you just cleaned some of the crap out of its systems ;)

But, what about auto's that don't allow you to drive them like you hate them? I mean, I can see how that works when you have a manual but not so much with an auto unless you are breaking speeds limits everywhere and driving with a lead foot :confused:

Alan

[td5130]

next time its cold when you start you TD5 you should notice it idles faster when cold then slows down when it starts to warm up

[twitchy]

It may be of course that you just cleaned some of the crap out of its systems ;)

But, what about auto's that don't allow you to drive them like you hate them? I mean, I can see how that works when you have a manual but not so much with an auto unless you are breaking speeds limits everywhere and driving with a lead foot :confused:

Alan


Without driving it manually sir you are correct..:D.......................maybe every now & then you should run it through the box manually.

[Gold_TD5]

Which Cummins engines are 2 strokes, have never seen one in a truck, I think you'll find that Cummins engines (Truck) are 4 stroke, Regards Frank.
To some people, a little bit knowledge is a dangerous thing.
As the Cummins VT 190 and 903/VT 903 were the same configuration/ similar V8 as the Detroit 892/692 TA/TTA V8/6, there was sometimes confusion that they were all two strokes but it was only the Detroit's.
Not forgetting the 6/71, 8/71, 6/53 and the blood tingling 3/53 (straight three) in a timberjack roaring through the bush.:)
Those two stroke GM's definened the term, DRIVE EM LIKE YOU HATE EM.
I miss the old days when diesel was cheap and trucks were fast.
Cheers Lionel

[big guy]

Great read
It does confirm what old mate engineer said.
Get glow plugs to turn off and start and go as soon as oil light is out.
Change oil often and do not let it idle is what I have always been told and done.

Good to see others are doing similar.

[Urban Panzer]

next time its cold when you start you TD5 you should notice it idles faster when cold then slows down when it starts to warm up

Yep it sure does, Mine will idle around 750 normally, but can be upto 1050 when starting in real cold temps, and you can "hear" her slow down as the temp goes up, its almost like an auto choke on petrol engined cars.