300TDi overheating

Guys, im after some ideas please. My 300 is running hot, but only at speeds of 50ish and above. Have done two days green laning, with loads of stop/starts and very slow moving and the temp gauge never goes above half. Even driving the roads between lanes the temp is fine but as soon as I hit the motorway and start to drive above 50 the temp starts slowly climbing, and will keep going into the red if I allowed it to. I would have thought that the faster you go - the more air going through the rad so should run cooler, but mine is doing the complete opposite.

Have cleaned all the crap from the outside of the radiator (which is missing a few fins, but doesn't look in to bad a shape) but that has not helped.

Any ideas on what could be causing it??

Cheers.

Air in cooling system ?

When was the last time you drained and refilled in radiator ?

rad dead, most water taking the short cut, recore it and get the tropical mod done and it will be much better

make sure the system is bled.

when above norm, check the top pipe for heat to see if the stat is working.

then place your hand all over the rad looking for cold spots to see if the rad is blocked.

A hand held temp scanner is great for finding out the actual temp,see flea bay.

Have never flushed it in the 3 years I have had it. Will start there. Would a nackered stat cause this?? Have never checked or changed this either. The top hose is red hot when the car is up to temp. What is the tropical mod??

Adam1979 said:

I would have thought that the faster you go - the more air going through the rad so should run cooler, but mine is doing the complete opposite.

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Drag / Inverse square law - to double your speed your power requirements multiple four fold. For example if you use 25 hp to achieve 40 mph then you need something like 100 hp to reach 80 mph. The engine has to be able to dissipate more heat the harder it works but with a poor radiator the increase in airspeed isn't enough to keep the temperature in check.

My rad had nearly no fins left, but worked fine. As already said, blocked rad or stuck shut stat or water pump. I think the 300TDi is particularly prone to the head warping if overheating so take care

I reckon you'll be looking at a new head gasket before long.

Cheers guys. Will be checking it out tomorrow to see what I can find. Have not let her overheat but pretty sure it would if I didnt drive at below 55mph.

remember to also check the rad for hot/cold spots

SteNova said:

rad dead, most water taking the short cut, recore it and get the tropical mod done and it will be much better

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What is the "Tropical Mod" ?

Thanks.

blocking up the hole in the side of the rad to force all the water through the core
http://www.aulro.com/afvb/90-110-13...13-defender-300tdi-radiator-tropical-mod.html

Have not had chance to look at this today (visitors) but have been thinking Would a badly adjusted injection pump cause the engine to run hotter?? Realized that this problem has only come about since I adjusted my pump. Basically, I totally buggered up the settings on my pump (long story) and after much fiddling got it at least useable again but with a lack of top speed. I have since turned the star wheel down quite a lot as it was suggested to me that it could be over fuelling. I have now got my top speed back but it is running hot. Co-incidence or???

Adam1979 said:

Have not had chance to look at this today (visitors) but have been thinking Would a badly adjusted injection pump cause the engine to run hotter?? Realized that this problem has only come about since I adjusted my pump. Basically, I totally buggered up the settings on my pump (long story) and after much fiddling got it at least useable again but with a lack of top speed. I have since turned the star wheel down quite a lot as it was suggested to me that it could be over fuelling. I have now got my top speed back but it is running hot. Co-incidence or???

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:doh: what exact bit did the adjust?

Adam1979 said:

Have not had chance to look at this today (visitors) but have been thinking Would a badly adjusted injection pump cause the engine to run hotter?? Realized that this problem has only come about since I adjusted my pump. Basically, I totally buggered up the settings on my pump (long story) and after much fiddling got it at least useable again but with a lack of top speed. I have since turned the star wheel down quite a lot as it was suggested to me that it could be over fuelling. I have now got my top speed back but it is running hot. Co-incidence or???

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op2:

I have oftentimes wondered if mine getting hot on the motorway could b caused by my pump tweaking

trax said:

:doh: what exact bit did the adjust?

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Long story really. At first I adjusted all three parts of the injection pump (not the main one at the back) and the engine performed really well, but after some time it got really sluggish and slow so I adjusted it some more. Never made no difference so I adjusted it some more . I drove it around for a few weeks with it performing pretty badly and then I stripped the injection pump apart to adjust it again and noticed that the fuel pin had got stuck (rusty). Once freed up the performance came back again but had no top speed at all. Flat out would only do just over 50 and the first sight of a hill I had to get all flinstone style and get my feet out of the floor and run along with it :bounce:

It was suggested to me that it was overfuelling so I have dropped the pump back down. To what I have no idea as I never kept no records of what I adjusted and how much. I now have much better performance and I have my top speed back but now it is running hot.

Could a badly adjusted pump cause the engine to run hot?? Im not pushing it on the motorway just trying to drive at a nice steady 60-65.

yeah, you raise the exhaust gas temp and can destroy things with the heat

you can fit an egt gauge on your dash for about 30quid, then go up a long hill and see what temps it gets too. i can't rem off the top of my head but 700ish max sounds about right.

Well my rad looks a bit fecked to be honest. Quite a lot of fins missing and the ones that are left in there can very easily be knocked out with a slight touch of my finger nail so that will be the first thing on my list. Just wish there was a way to reset my injection pump so I can start it all over again. At the moment I have no idea how much anything has been adjusted. I have not turned the pump up any more though over the last few weeks. The only thing I have altered is the star wheel, which I have turned down (anti-clockwise) by about quarter of a turn. This has made the engine perform a lot better but now I am having this heat problem.

Adam1979 said:

Well my rad looks a bit fecked to be honest. Quite a lot of fins missing and the ones that are left in there can very easily be knocked out with a slight touch of my finger nail so that will be the first thing on my list. Just wish there was a way to reset my injection pump so I can start it all over again. At the moment I have no idea how much anything has been adjusted. I have not turned the pump up any more though over the last few weeks. The only thing I have altered is the star wheel, which I have turned down (anti-clockwise) by about quarter of a turn. This has made the engine perform a lot better but now I am having this heat problem.

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you should be able to get it close or at least tune it properly. read a few times and you should be able to do it http://www.landroverweb.com/Pdf-files/Tuning_Land_Rover_Tdi_engines_Rev_2.pdf

if you pull the diaphragm and pin out you should see wear marks, one of them is the orig setting mark, reposition it.

maybe mark in marker the current setting, but make sure you can wipe them away when you find the right ones.

i'd also buy and fit an egt gauge.