a Td5 question for the gurus......

[DEFENDERZOOK]

if i was to drive from sydney to victoria.......in my Td5 fender......
since its all downhill......the engine will be in overdrive....that is foot off the throttle on the downhills......


this situation stops the injectors from fuelling to improve engine braking......
what effect will the lack of fuel have on my upper cylinders.........

as they wont have any fuel....there wont be any lubrication......will there.....?

[catch-22]

I would have thought that the crank splashing in the oil is all it would need....

edit: oops, just realised it was meant for gurus and you were probably after more then that.....

[DEFENDERZOOK]

the crank shouldnt splash in the oil......if it does....it will aerate the oil and reduce its lubricating efficiency.....


the crank is lubed by oil being pumped in through the oil galleries and through to the bearings....and then allowed to run back down to the sump.......


the combustion chamber does not have any lubrication other than the fuel entering the cylinder.....
unless the rings are worn or the valve guides are leaking......in this case you will have engine oil lubricating the cylinder......

this is visible to the naked eye.....as a blue smoke screen emitting from the tailpipe.......

[vnx205]

......... as they wont have any fuel....there wont be any lubrication......will there.....?
Only the same lubrication as a petrol engine, I suppose.

[Slunnie]

Does LPG lubricate the upper cylinders on LPG engines? If there is no combustion I would have assumed that there would be residual on the walls that would remain there. I don't think people have had a related problem when driving to Victoria before.

[vnx205]

if i was to drive from sydney to victoria.......in my Td5 fender......
since its all downhill......the engine will be in overdrive....that is foot off the throttle on the downhills......


this situation stops the injectors from fuelling to improve engine braking......
what effect will the lack of fuel have on my upper cylinders.........

as they wont have any fuel....there wont be any lubrication......will there.....?
Does it completely shut off the fuel?
Is that a feature of the TD5 or do other diesels do that too?

[DEFENDERZOOK]

so its just as safe heading to victoria as it is brisbane......?







i was just curious as im in overdrive situations quite a bit......
injected engines all do this.....

the old style carby motors were constantly sucking in some fuel.....giving some sort of lubrication at all times.....

[cwebb]

I've often wondered about the fuel shut-off in my TD5 manual Disco as well.
After hopping on the ferry over to Tasmania, I drove up Mt Wellington, next to Hobart. Over 1km high, obviously its all up-hill from the bottom.
After parking at the summit for 1/2 hour (yes it was freaking freezing), the temperature guage ALL the way down the hill did not come back up to operating temperature. As I was coasting down the hill the whole way, in 2nd-3rd-4th gear with zero throttle, obviously I was not in any way working the engine.
I suppose if my vehicle was an auto, then the engine may have been on idle and actually used fuel. However it is my belief that with a manual, even if it is only minimal, that the TD5 uses sweet bugger all of fuel on fast idle with no throttle.
Cheers everyone.

[29dinosaur]

so its just as safe heading to victoria as it is brisbane......?


From Sydney: Uphill to Brisbane? Downhill to Melbourne?:confused:

[Tank]

the crank shouldnt splash in the oil......if it does....it will aerate the oil and reduce its lubricating efficiency.....


the crank is lubed by oil being pumped in through the oil galleries and through to the bearings....and then allowed to run back down to the sump.......


the combustion chamber does not have any lubrication other than the fuel entering the cylinder.....
unless the rings are worn or the valve guides are leaking......in this case you will have engine oil lubricating the cylinder......

this is visible to the naked eye.....as a blue smoke screen emitting from the tailpipe.......
The Combustion Chamber in most diesels is in the top of the piston and requires no "oil Lubrication" the cylinder walls and the underneath of the pistons are lubed through oil squirters either from a hole in the con rod or oil nozzles in the crankcase aimed up at the pistons, no damage through "lack of oil lubrication" will occur because of deceleration. Many diesel engines suffer from fine cracks in the heads usually running from the injector nozzle to the valve seats. A lot of this damage is caused by working the engine hard, say up a long hill, with a load and then coasting down the other side, which cools the combustion area very quickly. It is good practise after a long hard (hot) haul up a hill to actually drive down the hill instead of coasting with no throttle, it stops the head from cooling rapidly, Regards Frank.

[gruntfuttock]

The Combustion Chamber in most diesels is in the top of the piston and requires no "oil Lubrication" the cylinder walls and the underneath of the pistons are lubed through oil squirters either from a hole in the con rod or oil nozzles in the crankcase aimed up at the pistons, no damage through "lack of oil lubrication" will occur because of deceleration. Many diesel engines suffer from fine cracks in the heads usually running from the injector nozzle to the valve seats. A lot of this damage is caused by working the engine hard, say up a long hill, with a load and then coasting down the other side, which cools the combustion area very quickly. It is good practise after a long hard (hot) haul up a hill to actually drive down the hill instead of coasting with no throttle, it stops the head from cooling rapidly, Regards Frank.

That is interesting, I did not know that.

[Captain_Rightfoot]

The Combustion Chamber in most diesels is in the top of the piston and requires no "oil Lubrication" the cylinder walls and the underneath of the pistons are lubed through oil squirters either from a hole in the con rod or oil nozzles in the crankcase aimed up at the pistons, no damage through "lack of oil lubrication" will occur because of deceleration. Many diesel engines suffer from fine cracks in the heads usually running from the injector nozzle to the valve seats. A lot of this damage is caused by working the engine hard, say up a long hill, with a load and then coasting down the other side, which cools the combustion area very quickly. It is good practise after a long hard (hot) haul up a hill to actually drive down the hill instead of coasting with no throttle, it stops the head from cooling rapidly, Regards Frank.
Do we know if this specifically happens in td5's?

If I can I try and do this to save fuel :o

[Redback]

From Sydney: Uphill to Brisbane? Downhill to Melbourne?:confused:

I'm with you, WTF Tony:confused:

[rick130]

if i was to drive from sydney to victoria.......in my Td5 fender......
since its all downhill......the engine will be in overdrive....that is foot off the throttle on the downhills......


this situation stops the injectors from fuelling to improve engine braking......
what effect will the lack of fuel have on my upper cylinders.........

as they wont have any fuel....there wont be any lubrication......will there.....?

mate, that's the least of your worries if you're heading to Mexico :D















and I can't believe you lot have been sucked in by the 'Zook :D

[DiscoStew]

From Sydney: Uphill to Brisbane? Downhill to Melbourne?:confused:

Depends on you where leave from of course but Sydney GPO elevation is 70m above sea level and Melbourne GPO is 27m. So there is a nett downhill of 43m over 880km.

Brisbane GPO is at 26m so is downhill as well.

Probably best not to do these trips then eh?:wasntme:

[stevo]

there is oil jets that spray oil up into the piston for cooling, I was doing a trip through the Vic high country going down a steep rocky and long track by the time I got to the bottom the gauge was back in the cold zone

[Zute]

As a long-distance truck driver, I put the truck into neutral when traveling from Sydney to Melbourne and coast all the way (sometimes reaching speeds of 130km/h) The fuel I save I sell on the Black market (what my Boss doesnt know wont hurt him) I leave the engine Idling so its powering the air system so the air horns will still work.







:Dlol

[lokka]

This must be a trick question as ive seen how zook drives ive even been a passenger and the only time his right pedal is off the floor is when the fenda is stoped ......

I think hes just having a shyte stir as he only knows 2 speeds flat out or stoped :p:p:p:p:p:D:D:D:D:D:D

[PAT303]

Some of you blokes need a good night's sleep. Pat

[DEFENDERZOOK]

actually i was curious to find out if we are actually wearing out our engines faster than we should be......


in the days of carbies......fuel was entering the engine even in overrun conditions.......
so the fuel was actually lubricating the upper cylinder....thats all the bits above the piston rings......up to the valves.....


but with todays technology......the fuel can be shut off completely in overrun situations......


its more of a general for all injected engines.......petrol and diesel......


its just curiosity more than anything else.......i was just curious if anyone had actually read or heard any facts regarding this........


its nothing to stress over......the engines are just doing what they are designed to do........

[Redback]

actually i was curious to find out if we are actually wearing out our engines faster than we should be......


in the days of carbies......fuel was entering the engine even in overrun conditions.......
so the fuel was actually lubricating the upper cylinder....thats all the bits above the piston rings......up to the valves.....


but with todays technology......the fuel can be shut off completely in overrun situations......


its more of a general for all injected engines.......petrol and diesel......


its just curiosity more than anything else.......i was just curious if anyone had actually read or heard any facts regarding this........


its nothing to stress over......the engines are just doing what they are designed to do........

Hmmm a diesel with carbies, never seen one, but then you reckon Melbourne is downhill:p:p

[DEFENDERZOOK]

Hmmm a diesel with carbies, never seen one, but then you reckon Melbourne is downhill:p:p



have you seen a map of australia.......?

you go up to get to brisbane........and down to get to melbourne.....

[ozscott]

Its a good point mate. My 02 runs petrol and LPG and even the LPG shuts off the solenoid for the LPG after 3 seconds or so or no throttle being applied (only above 2000 rpm or so) because it takes its cue from the petrol fuel injector pulse, and the fuel injector pulse cuts off completely as a fuel saving strategy under such conditions - the petrol cut off is covered well on the RAVE cd...I know that on LPG if you on a long downhill run you squeeze the throttle and you hear the solenoids opening (I have the rear tank solenoid inthe load area with the tanks) and off she goes with no hesitation, however if you tromp the throttle in such situations there is a slight hesitation because the vapour hose is empty or almost empty of LPG and it has to pick up from the convertor - on petrol of course the fuel is in the rails and ready to be injected in a split second so its not noticeable at all on petrol.

Cheers

[Dougal]

The Combustion Chamber in most diesels is in the top of the piston and requires no "oil Lubrication" the cylinder walls and the underneath of the pistons are lubed through oil squirters either from a hole in the con rod or oil nozzles in the crankcase aimed up at the pistons, no damage through "lack of oil lubrication" will occur because of deceleration. Many diesel engines suffer from fine cracks in the heads usually running from the injector nozzle to the valve seats. A lot of this damage is caused by working the engine hard, say up a long hill, with a load and then coasting down the other side, which cools the combustion area very quickly. It is good practise after a long hard (hot) haul up a hill to actually drive down the hill instead of coasting with no throttle, it stops the head from cooling rapidly, Regards Frank.


The engine gets the same cold air charge in every stroke whether it's working hard uphill or idling. The only difference is any heating due to the turbo and cooling from the intercooler.
From there the thermal mass in the engine keeps it from cooling anywhere near fast enough to crack.

Accelerating a truck downhill is suicide (murder-suicide if anyone else is on the road). I know one truckie who tried it, hit 160km/h then asked for a speed limiter to be put in the truck to save him from himself.

If it was necessary to keep heat in the engine, an exhaust brake does just that.

[BradM]

Go West Instead You cannot go wrong

BradM

[Tank]

actually i was curious to find out if we are actually wearing out our engines faster than we should be......


in the days of carbies......fuel was entering the engine even in overrun conditions.......
so the fuel was actually lubricating the upper cylinder....thats all the bits above the piston rings......up to the valves.....


but with todays technology......the fuel can be shut off completely in overrun situations......


its more of a general for all injected engines.......petrol and diesel......


its just curiosity more than anything else.......i was just curious if anyone had actually read or heard any facts regarding this........


its nothing to stress over......the engines are just doing what they are designed to do........
In a petrol engine unburnt fuel actually "delubricates" the combustion area and the bore, not good.
Zute has the right idea, do what he said.
Regards Frank.

[Tank]

quote=Dougal;636960]The engine gets the same cold air charge in every stroke whether it's working hard uphill or idling. The only difference is any heating due to the turbo and cooling from the intercooler.
From there the thermal mass in the engine keeps it from cooling anywhere near fast enough to crack.

Accelerating a truck downhill is suicide (murder-suicide if anyone else is on the road). I know one truckie who tried it, hit 160km/h then asked for a speed limiter to be put in the truck to save him from himself.

If it was necessary to keep heat in the engine, an exhaust brake does just that.[/quote]


The engine produces more heat under load up a hill because 1. it is not moving as fast, so less cooling air at, say 15klm/h than at 100 klm/h and 2. the engine is working harder at and at or near max. revs. I didn't suggest that you drive downhill with pedal to the metal, only an idiot would do that, occasional use of the throttle where appropriate.
Maybe you have an alternative theory as to why diesel heads tend to get hairline cracks in the combustion area and valve seats, I guess Mercedes-Benz and Cummins tech bulletins are wrong, Regards Frank.

[Tank]

Do we know if this specifically happens in td5's?

If I can I try and do this to save fuel :o
Usually not, but it is common in full size trucks, if your TD5 gets hotter , pulling a load up a long hill, then that's normal, use a bit of throttle downhill, where appropriate, the engine will cool less quickly, Regards Frank.

[Ruslan]

I've read similar discussion on other cars forum, and they came to conclusion that using engine breaking technique on long distance wearing an engine faster. :angel:

Personally, I prefer combination of neutral+wheel breaks and engine breaking.

[bushrover]

I rolled from Cairns to Melbourne without throttle rolled all the way across the Nullarbor and only had to touch the throttle again in Kalgoorlie to start again at traffic lights. I reckon momentum could have rolled me all the way up hill to Leonora if the lights weren't red. Didnt have any upper cylinder lubrication problems!

To much diesel (overfuelling) will cause excessive wear (cylinder washing) and overheating. If you have unit type injectors and the seals leak you can stuff an engine very quickly. Diesel although an oil has very little lubrication properties.

Dont know how to post a link to the Markets section (help) but there is a free dead County (not complete) there if someone in the Pilbara wants it.

[Dougal]

The engine produces more heat under load up a hill because 1. it is not moving as fast, so less cooling air at, say 15klm/h than at 100 klm/h and 2. the engine is working harder at and at or near max. revs. I didn't suggest that you drive downhill with pedal to the metal, only an idiot would do that, occasional use of the throttle where appropriate.
Maybe you have an alternative theory as to why diesel heads tend to get hairline cracks in the combustion area and valve seats, I guess Mercedes-Benz and Cummins tech bulletins are wrong, Regards Frank.

If you've driven with an EGT gauge you'll realise that a light throttle downhill does absolutely nothing.
My idle exhaust temps are around 170degC when fully warm, can reach 750 deg C when pushed hard.
400 deg C is roughly the 100km/h cruise level. Enough pedal to give 400 deg C downhill will have the truck doing the old imperial ton.

Heads crack due to crappy design. Idling for cooldown is standard practice everywhere after running at full load, if there was a problem with it, if that cracked heads it would have been discovered at least 50 years ago.

I can't believe any truck engine maker would advocate accelerating downhill. They'd be sued to hell and back. Do you have a link to this tech bulletin?

[Tank]

If you've driven with an EGT gauge you'll realise that a light throttle downhill does absolutely nothing.
My idle exhaust temps are around 170degC when fully warm, can reach 750 deg C when pushed hard.
400 deg C is roughly the 100km/h cruise level. Enough pedal to give 400 deg C downhill will have the truck doing the old imperial ton.

Heads crack due to crappy design. Idling for cooldown is standard practice everywhere after running at full load, if there was a problem with it, if that cracked heads it would have been discovered at least 50 years ago.

I can't believe any truck engine maker would advocate accelerating downhill. They'd be sued to hell and back. Do you have a link to this tech bulletin?
You seem to have a problem reading what I wrote, I am just relating my experiences of 30 years+ of Heavy truck mechanicing, if you would like to put forward your expertise, go ahead, but don't question my actual experiences, if you want tech bulletins from Cummins and M/B from 30 years ago, go for it, you know how to use a computer, Regards Frank.

[Kettle]

I apologise for not being in the right place, but how do you ask a question and start off a new forum?? I have never done this before and don't know what to do. Help please.

[Tins]

I apologise for not being in the right place, but how do you ask a question and start off a new forum?? I have never done this before and don't know what to do. Help please.

Hi. Open the forum you want to post in ( Technical Chatter, Discovery, RRC or whatever ) so you have the list of threads in front of you and at the top left, under the heading you will see the button "New Thread". Click on that. Stick something in the "Title" bit and then post in the message section. You'll soon get the hang of it.

Navigate to the "Home" page and you'll see rules and guidelines. Have a read of that. Enjoy!

[Judo]

I just read this whole thread. Awesome.

[PhilipA]

I think it was in the early days of this forum that someone asked did it save fuel by angel gearing it downhill in a V6 Commodore.

When I replied to him that the ECU cuts off the fuel by looking at road speed, revs and throttle position he abused me and told me this was impossible.

I gave up then.

BTW I recently read that the latest Euro cars now do the angel gear trick by stopping the engine on long down hills, so there must be some fuel being injected when overrun cutoff occurs in the older ones or there would be no economy benefit.
AFAIK it must be tied to the auto stop start as you must have electric brakes and steering for this to happen.
Ah only the clutch is disengaged so the engine is still idling although the new Bosch system cuts off the engine..
Regards Philip A
http://www.car-engineer.com/stop-start-coasting-function-developed-bosch/
http://www.volkswagen.com.au/en/technology_and_service/technical-glossary/coasting-function.html
products.bosch-mobility-solutions.com/.../SG_Sheet_Start_stop_coasting_en_highres_20130905-1.pdf