TDI 300 Overheating problems

[Jonesy1972]

I am hoping someone might be able to give some advice/solutions to my Disco overheating.
In the last few months my TDI300 starts to run hot on a warm day (35 degrees) with the air cond running or towing an empty trailer.
I have sent the radiator in for a clean, checked the thermostat is operating, replaced the water pump, flushed and cleaned the engine, changed the coolant and replaced the the thermo fans.
I am running out of ideas on what to do next. The only other things I think it could be would be the viscous fan? Or Injector timing. Has anyone else had similar problems and can shed some light?

Regards
Jonesy1972

[Judo]

Why do you think it's running hot? Dash temp gauge? What does it read? Do you have an after-market temp gauge of any kind? What is the reading?

[SouthOz]

I would check the viscous fan for leaks.

Dave

[ade]

put a new viscous hub on it

[Jonesy1972]

It is the standard temperature gauge. It sits in the usual position when driving in normal conditions but rises when under load and at high revs.

[Jonesy1972]

Is there a way to test the viscous fan?

[SouthOz]

Mine has dust on it where it is leaking just behind the spring. Its on its way out. Next thing on my list.

Dave

[Jonesy1972]

If you find a cheap viscous fan centre let me know.
Regards
Jonesy

[SouthOz]

Im not sure a cheap one is the answer. Ive heard of quite a few new ones not being any better than the one thats being replaced. The OEM ones will be expensive but mines lasted 220,000 km so I will be getting OEM if they aren't overpriced. I will probably get one from the UK.

Just had a look at evilbay.

http://www.ebay.com.au/itm/LAND-ROVER-DISCOVERY-1-300TDI-DIESEL-VISCOUS-UNIT-94-/220778607638?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item33676e3416#ht_1781wt_1394

Land Rover DISCOVERY 300TDi & Defender 300TDi Viscous coupling for engine fan | eBay (http://www.ebay.com.au/itm/Land-Rover-DISCOVERY-300TDi-Defender-300TDi-Viscous-coupling-for-engine-fan-/251209399351?pt=AU_Car_Parts_Accessories&hash=item3a7d3f3c37&_uhb=1#ht_1243wt_1160)

Land Rover Defender, Discovery 300TDi Viscous Fan Coupling | eBay (http://www.ebay.com.au/itm/Land-Rover-Defender-Discovery-300TDi-Viscous-Fan-Coupling-/120738845002?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item1c1c98914a&_uhb=1#ht_1037wt_903)

http://www.daviescraig.com.au/Fan_Clutches-Fan_Clutches-details.aspx

Might have to look into this a bit more.

Dave

[Jonesy1972]

Have a look at Rimmer Bros. website in the UK, that's where I get most of my parts.
Regards
Jonesy1972

[Discovery-94]

you can check the fan - it should always have some resistance, i.e not spin freely (especially when warm).

have you properly bled your cooling system after flushing and replacing the coolant? you could have some air in there - which might give a false reading in standard dash gauge. ((--HIGHLY recommend an aftermarket unit!!--))
also, the temp sensor in the thermostat housing could be on its way out - I had one showing me its hot when the engine was cold, straight after switching ignition on...
and you say you have replaced the thermo fans - are you positive they switch on? there is also a little switch in the thermostat housing which turns them on above a certain temperature, if its buggered it wont - so make sure you can hear them running.

and lastly, do you know whether the injection pump has been tampered with?
Mine has, to give it more whoomp, and on a hot day (late 30s, early 40s) with a/c running climbing up longer hills the temp gauge can rise slightly, however I also have a temp sender on the block so I can keep an eye on it (the dash gauges are.....average)

Good luck!

[SLOWBOAT]

Rover Parts in Ballarat genuine is about $100!

[waltsd]

Have a look at Rimmer Bros. website in the UK, that's where I get most of my parts.
Regards
Jonesy1972


i just bought one from Rimmer Bros, much cheaper than any in OZ, but haven't had a chance to fit it yet. It's a BRITPART brand. I am having the same problem of heating up to 104 degrees when loaded up, air-conditioning on and up hills. (have an engine guardian fitted to the thermostat housing bolt). Otherwise ok running. Will be fitting it over the next week and testing it on a long trip to SouthEast WA shortly.

[Jonesy1972]

I have ordered the viscous coupling from Rimmer Bros. in the UK. The Landrover viscous coupling was $195, the OEM was $85 and the aftermarket was $41. I went with the OEM because the viscous coupling spins too fast for me to read "Landrover" cast into the aluminium.
I'll let you know when it gets here ( it's on back order) and if it solves the problem.

Regards
Jonesy1972

[Jonesy1972]

you can check the fan - it should always have some resistance, i.e not spin freely (especially when warm).

have you properly bled your cooling system after flushing and replacing the coolant? you could have some air in there - which might give a false reading in standard dash gauge. ((--HIGHLY recommend an aftermarket unit!!--))
also, the temp sensor in the thermostat housing could be on its way out - I had one showing me its hot when the engine was cold, straight after switching ignition on...
and you say you have replaced the thermo fans - are you positive they switch on? there is also a little switch in the thermostat housing which turns them on above a certain temperature, if its buggered it wont - so make sure you can hear them running.

and lastly, do you know whether the injection pump has been tampered with?
Mine has, to give it more whoomp, and on a hot day (late 30s, early 40s) with a/c running climbing up longer hills the temp gauge can rise slightly, however I also have a temp sender on the block so I can keep an eye on it (the dash gauges are.....average)

Good luck!

I have bled the system after I filled with new coolant (learned that lesson a few years ago). I believe the dash gauge is correct because it only rises slowly under load or at high revs, I let the gauge get upto the 3/4 mark and pull over. The temperature slowly decreases within 5 mins back to normal. To reinforce this belief, I have to climb Greenmount hill everyday in the arvo and the car gets hot on the way up, when I hit the crest and the load is removed the car quickly cools down on the downhill/level ground.

The thermo fans are working. They work immediately when I turn the air cond. on and they also work when the car is hot and I have to pull over let it cool down.

As for the injector pump, I've been told by a couple of landrover mechanics that the injector pump timing can not be adjusted. The only reason it maybe out would be due to the timing belt needing replacing or the injector pump is worn and needs to be rebuilt.

At the moment I'm just working through the cheaper options first.

Thanks for your help. I think I'll wait to see how the viscous fan goes.

[justinc]

I have bled the system after I filled with new coolant (learned that lesson a few years ago). I believe the dash gauge is correct because it only rises slowly under load or at high revs, I let the gauge get upto the 3/4 mark and pull over. The temperature slowly decreases within 5 mins back to normal. To reinforce this belief, I have to climb Greenmount hill everyday in the arvo and the car gets hot on the way up, when I hit the crest and the load is removed the car quickly cools down on the downhill/level ground.

The thermo fans are working. They work immediately when I turn the air cond. on and they also work when the car is hot and I have to pull over let it cool down.

As for the injector pump, I've been told by a couple of landrover mechanics that the injector pump timing can not be adjusted. The only reason it maybe out would be due to the timing belt needing replacing or the injector pump is worn and needs to be rebuilt.

At the moment I'm just working through the cheaper options first.

Thanks for your help. I think I'll wait to see how the viscous fan goes.

Well that's a load of cobblers.

I have to check and adjust the timing EVERYTIME I replace a timing belt, 200 and 300 Tdi.

There are also performance timing tweaks like extra plunger lift etc etc to be performed.

Search function should show up a bit of info on 300Tdi timing adjustment/ tweaking.

JC

[Spel1]

You said you sent the radiator in for a clean. Was it just flushed or properly rodded? The symptoms you mention - heating gradually on a hill then cooling off quickly when no more load - are exactly the ones I experienced before getting the core replaced on my radiator. (A partially blocked rad will not be able to overcome the temps on a hill, but is adequate for minimal loads). My old one was nearly totally blocked, since the fix I have had no overheating problems, even under load towing a full trailer up the hill to Ballarat from Melbourne.

[Jonesy1972]

You said you sent the radiator in for a clean. Was it just flushed or properly rodded? The symptoms you mention - heating gradually on a hill then cooling off quickly when no more load - are exactly the ones I experienced before getting the core replaced on my radiator. (A partially blocked rad will not be able to overcome the temps on a hill, but is adequate for minimal loads). My old one was nearly totally blocked, since the fix I have had no overheating problems, even under load towing a full trailer up the hill to Ballarat from Melbourne.

I took it into Natrad and they said it was 20% blocked and cleaned it and charged me $140. I am not sure what they did, do you think I need to take it back and get the core replaced?
Regards
Jonesy

[bigcarle]

GET AN ENGINE MONITOR for the temperature
the watchdog goes under a bolt on the head and measures the HEAD temperature not the water or lack thereof. this is WAY more reliable than the OEM gauge which works like a warning light by the time it works it is too late the damage is done

[Spel1]

I took it into Natrad and they said it was 20% blocked and cleaned it and charged me $140. I am not sure what they did, do you think I need to take it back and get the core replaced?
Regards
Jonesy


Don't know for sure that is your problem, it just sounds like the symptoms I had with my radiator. I would call Natrad and ask how they cleaned it, whether it was a just a chemical flush or was rodded, (which involves taking it apart and physically cheaning the tubes). Wouldn't hurt to ask and would help with eliminating possibilities. Simon

[wrinklearthur]

Don't know for sure that is your problem, it just sounds like the symptoms I had with my radiator. I would call Natrad and ask how they cleaned it, whether it was a just a chemical flush or was rodded, (which involves taking it apart and physically cheaning the tubes). Wouldn't hurt to ask and would help with eliminating possibilities. Simon

X2

Rodding is the only way, back flushing dosn't work IMHO, as the bleed hole in the diversion baffle half way down the radiator tank, bypasses the fluid away from the tubes in the core.
.

[Jonesy1972]

Don't know for sure that is your problem, it just sounds like the symptoms I had with my radiator. I would call Natrad and ask how they cleaned it, whether it was a just a chemical flush or was rodded, (which involves taking it apart and physically cheaning the tubes). Wouldn't hurt to ask and would help with eliminating possibilities. Simon

I think I'll take it to someone else to get done. I wasn't happy with Natrad anyway. Natrad said they pressure tested the radiator to 25PSI but when I got it home it lost all of the coolant as fast as I was pouring it in. They failed to see the 5mm slip in the side. They fixed it with no complaint but it doesn't instill confidence.
Regards
Jonesy1972

[Nundle]

Thanks for the post Jonesy1972. I'm experiencing the same problem at the moment. Engine monitor sounds like a wise investment. Keep us posted on the outcome.
Nundle

[Jonesy1972]

Thanks for the post Jonesy1972. I'm experiencing the same problem at the moment. Engine monitor sounds like a wise investment. Keep us posted on the outcome.
Nundle

I am currently enquiring about an aftermarket radiator from the UK for $152 excluding freight. I'll let you know the freight costs and how many core it is when they get back to me.

Regards
jonesy

[Jonesy1972]

How many core is a TDI 300 radiator? I thought they were a 4 core but I can't check without dumping my coolant.
I received an email from Rimmer Bros last night to say their radiators were "2 core, I think". I asked for them to find out definately but they returned by asking how many core was mine.
I know the series 3, 2.25Lt petro was a 3 core and I can't see them going less.
Any ideas/help?

regards
Jonesy

[peter51]

The efficiency of the radiator will be degraded even if you just rod it. The galleries will never be the same as new. A degraded radiator will not cut it on hot humid days – humid days mean less air density and less heat transfer from radiator to the air. The temperature differential between inlet and outlet will always be greater in the new radiator. Coolant flow rate through the rad is critical to the rate of heat exchange to the air. Under heavy load a 2.5Tdi needs more than 170 litres per minute passing through the system – E.G the minimum safe flow figure for a 2.5TDi jeep at 88km/hr on a 6% climb 35degrees and 90% humidity is 195litres/min. The coolant mix at the rad inlet was measured at 104 degrees and the coolant mixture was 18% vapour under this load.
At the 200,000 km mark just budget for a new radiator and a complete cooling system renewal. Do it all at the same time as you do the timing belt – new pump, thermostat radiator, viscous fan, expansion cap, hoses etc. Throw the old radiator away as it will never be as efficient at transferring heat to the air as a new one. Use some gauze to stop insects bodies from blocking the rads.
A 2.5litre tubo diesel must dissapate twice the energy to the cooling system as a 2.5petrol - Heat rejection of a 2.5litre turbo diesel is 144kW whereas a 2.5L petrol engine only requires 76kWi.e the radiator and oil cooler must be able to absorb double the energy.
Here is some ifo on how of how much heat needs to be dissappated by this radiator in a 300 TDi.
I have an 97 300 TDi with EGt guage, aftermarket water temp, oil temp,oil pressure, boost guage and an accurate head temp sender attached close to the exhaust port on number one. I also have low coolant alarm plumbed into top of new radiator from enginesaver.com.au
Normal EGT is 300-350 and water 85 – factory guage shows under half .
Under load, EGT elevates instantaneously to 550 degrees celcuis and will stay there. Boost is about 11- 14psi. The head temp immediately rise to 100-105. The water follows quickly from 85 to 95. Oil temp rises rapidly thereafter. The factory guage does not move. All my cooling system components are new.
Switch the AC on, maintain the load, and the water temp moves higher very quickly up to 99.
Any weakness in the system such as a slight pressure release or less than 50/50 coolant mix will cause localised nucleate boiling in your head resulting in more trouble. The resulting vapour travesl to the water pump where they can cause pump cavitation. Any minor cavitation at the pump results in less flow. This leads to further issues.
Nucleate boiling is the same as the bubbles that start forming in the bottom of your jug at home – and yet actual boiling has not happened.
The ethylene glycol water mixture can easily operate as a liquid/ vapour mixture. The vapour content is determined by temp and pressure. Once the coolant temp is reduced below the saturation temp (100c in a 50/50 coolant mixture) then the pump will receive liquid only correct flow rate will result. In a 50-50 mix ethylene glycol water mixture the boiling point is 130C.
Nucleate heat transfer is a hybrid form of convective heat transfer. The coolant is allowed to vapourise against the engine. This absorbs far more energy than by conventional means. The vapour is condensed in the radiator. System px is very important in this method and expansion of coolant vapour must be accommodated with an expansion tank. If the coolant reaching the pumps has any vapour or is too hot then the flow rate drops immediately.

So to avoid nucleate boiling you have to have good quality and correct ratio of coolant – This will allow the coolant to operate under pressure without loaclised/nucleate boiling. That way the pump and radiator can continue to function at their optimum.
It’s a highly tuned system. A slight weakness in one item will overload the others. If you want the engine to go through to 500,000km then you should budget for a complete cooling system overhaul.
BTW – this applies to all vehicles – there are just as many so called bombproof Toyotas and Nissans being cooked every day out there due to only replacing cooling system parts as required.

[wrinklearthur]

An excellent article Peter and thank you for the time you spent writing it up.
The only small criticism I have, is that you haven't referenced your sources.
But then who am I to say this. :p


The efficiency of the radiator will be degraded even if you just rod it. ---- Throw the old radiator away as it will never be as efficient at transferring heat to the air as a new one. ---- It’s a highly tuned system. A slight weakness in one item will overload the others. If you want the engine to go through to 500,000km then you should budget for a complete cooling system overhaul.
I have fitted a new radiator to one of my 300TDi D1's ( 'Fred' ), that one action alone cured all the problems that I was having when towing heavy loads.


Any weakness in the system such as a slight pressure release or less than 50/50 coolant mix will cause localised nucleate boiling in your head resulting in more trouble. The resulting vapour travels to the water pump where they can cause pump cavitation. Any minor cavitation at the pump results in less flow. This leads to further issues. --- If the coolant reaching the pumps has any vapour or is too hot then the flow rate drops immediately.
To me, your description of pump cavitation has the reason that the cheap after market water pumps fail so soon.
The plastic cage around the water pumps bearing rollers, isn't up to the extra heat generated under Australian conditions, the bearing rollers cage then deforms with extra heat and lets the water pump shaft move into misalignment .


BTW – this applies to all vehicles – there are just as many so called bombproof Toyotas and Nissans being cooked every day out there due to only replacing cooling system parts as required.
Some cooling systems have been designed with a far greater threshold to guard against temporary overload, most tractor designs have this feature.

Thanks again Peter for your work .
.

[peter51]

Regarding producing references - Here they are.
The figures I quoted were taken from a collection of automotive engineering articles in regard to vehicle cooling systems – from the state library. In that collection was a report on the introduction of the Jeep diesel into the tropical markets. The petrol version never overheated, whereas the 2.5 turbo diesel continually overheated. Recall that I said turbo deisels typicalyl require twice the heat rejection as a petrol of the same capacity.The information below is taken from the engineers report on how they modified the cooling system to stop the overheating. It is a good example of how much design goes into cooling systems and obviously how the owner must keep up with the maintenance.
Attached is a table showing temperatures and flow rates before and after modification. You can see that for a 2.5 turbo diesel quite high flow rates are required. The 300TDi would require similar figures – you can see that all components must be in top condition to maintain the design rad inlet temps, outlet temps, vapour content, coolant flow and static pressure at pump inlet. The total pressure being a combination of dynamic (fluid speed) and static pressure
The table is attached below.
In short the problem was lack of flow rate, excess vapour at the pump inlet and too low static pressure at the pump inlet. The radiator was also enlarged to allow for an increase in flow rate.
Increase in cooling system pressure will increase the boil point. This allows higher engine temperatures and better economy. This increased pressure also reduces the amount of vapour in the system and therefore lowers cylinder head temperatures.
If there is an overheat of the coolant , or drop in pressure, boiling – then vapour will form and as the coolant enters the pump inlet, this vapour will expand due to the low pressure at the centre of the pump. As the amount of vapour increases at the pump inlet then the flow decreases. When the pump reaches a critical vapour volume it will cavitate and coolant will no longer flow A typical centrifugal pump can only handle up to 25% vapour before it begins to reduce coolant flow rate.
If the flow rate is to be increased, as in the above example, then the radiator must also be increased to handle this flow rate.
Additionally, the inlet pipes of the pump must be as large as possible to balance the inlet and outlet conditions.
Increased flow rates were achieved by increasing the diameter of the pump impeller and pulley size was reduced – 1.15 drive ratio to 1.43 ratio. In the Jeep diesel case above the impeller blades were only slightly increased in diameter up to the maximum of the original casting, however more importantly, a cone head pump impeller was moulded into the centre of the impeller to more effectively force any vapour through the pump.

Hopefully all Landrover owners and especially those with old turbo diesels will dig deep into their pockets to completely overhaul their cooling system in order to restore it to design conditions
Regards
Peter

[Jonesy1972]

I received the new viscous coupling yesterday and did a run up the hill, air cond on, 3000RPM in 3rd gear doing 80km/h on a 35 degree day and she didn't get hot (normally she would).
When I pulled the old viscous coupling off I was clear to see it had leaked.
The only thing left to replace on the cooling system is the radiator but I need to know how many cores does the TDI300 radiator have?
Regards
Jonesy
PS. If you buy a viscous coupling do yourself a favour and buy the $14 spanner to remove the old fan.

[Dave Field]

my 300tdi had same problems exactly. tow a caravan around for 12 months did all the things you have done to try to fix, including flushing radiator( this was done by a landrover mob). Finally fixed the problem with a new radiator never has it overheated again

[tassydisco]

Exactly same thing happened to me to. I chased the problems for 3 years fixed everything I could think of, had the radiator done twice both times they told me it was fine. Finally bought a new one 3 months ago, all my overheating problems have disappeared. Should have done it a long time ago! Only cost me 360 delivered for an aluminium cored radiator from LRA. Now I can tow anything up any long hills all day long and it will never go above 90 degrees.

[waltsd]

Just come back from trip to Esperance region from Perth After fitting the new viscous fan. I can't believe how much "howl" I now get from the new fan clutch when it gets up to temperature and need to drop it down to 4th to get up some hills. Also noticed the temperature actually drop going up some hills, which I never seen before (engine guardian). No overheating all the way back on a 35 degree day up hills and loaded with camping gear. Obviously the new viscous fan is working! Great to hear roar, when needed!

I did have one day it went up to 100 degrees, but on that day it was 42 and going straight into a 50km/h head wind. Maybe the rad flush/new rad would have solved this completely also??

[Jonesy1972]

It was warm today and I gave it everything I could to try and make it hot, air cond. on, 3000 RPM going up Greenmount hill, tail gating the car in front (no clean air). So it appears the viscous fan is working fine. But I will be investing in a new radiator. If anyone has bought one recently for a good price send details.

Regards
Jonesy

[Jonesy1972]

I haven't found a new affordable radiator yet, but the new fan seems to have fixed the problem. Yesterday was a 38 degree afternoon and I dragged a bobcat up Greenmount hill doing 50km/h at 3000RPM (5 mins continuous running) and the temp gauge didn't move.
So, touch wood, I think I've solved the problem.
Thanks to everyone for their help.
Regards
Jonesy

[Spel1]

Just come back from trip to Esperance region from Perth After fitting the new viscous fan. I can't believe how much "howl" I now get from the new fan clutch when it gets up to temperature and need to drop it down to 4th to get up some hills. Also noticed the temperature actually drop going up some hills, which I never seen before (engine guardian). No overheating all the way back on a 35 degree day up hills and loaded with camping gear. Obviously the new viscous fan is working! Great to hear roar, when needed!

On the basis of this and other posts, and a small observed rise in temp from the useless standard temp gauge on a hot day with the aircon on, I bought one of the TM2 engine watchdogs that take temp readings from the metal. (I bolted the sender to the stud behind the thermostat). On a trip to Adelaide from Melbourne (steep hills on the way out both ways) the temp touched 104 - but the dash gauge didn't move. After some observing, the temp rises were only with slow speeds and lugging up hills - higher speeds (with airflow) all was good. I bought a new viscous fan coupling and what a difference - on the same hill on the way to Ballarat last weekend where I previously hit 104, temp did not go above 94 degrees. Pretty much like this across the board, much lower and more stable. Thanks for the useful information. Simon

[peter51]

Spel1 is the previous post followed a clever strategy that all should follow. The TM2 is quite accurate and by simply bolting it to the thermostat housing you get a good approximation of the water temp before it enters the radiator. These devices are very simple and fast to fit - but you should buy some heat sink paste from Jaycar to put around the bolt to sensor interface. Be aware the indicated temperature will be in error by up to 5 degrees because you are not in direct contact with the water.



Now if it reads over 105 degrees under moderate load - you have major problems.
Now start replacing cooling system parts - starting with the viscous fan - and then the radiator( they are cheap compared to a new head) - check the nonreturn valvle on the overflow bottle on the 300TDi's etc etc. Don't skimp on the coolant quality and concentration - using plain water does work - but not for long.

If you can get it down to 98 degrees under extreme load then you have a very good cooling system.

If you have access to an infrared thermometer, you should see a drop of 15 degrees between the top and bottom of the radiator - on the metal inlet and outlet pipes.

Now fit a low water coolant alarm (sensor fits into the top rad plug on the 300TDi) and you can drive anxiety free.

BTW:You can also fit an accurate mechanical/electrical gauge sender into the top of the thermostat housing - 300TDi - ENZED will have the adaptor 1/8 NPT. This will give you an accurate water temp. If you want to know about the relative accuracies of various gauges then do a search on autospeed website - the have a gauge test on known brand gauges. The eBay ones are out by 5 dgress - I know as I have bought 2 and they both read 95 degrees when the ater is 100 degrees.