overheating confusion

miktdish · Jul 5, 2016

I've searched through the archives but must have missed the relevant post. Having just fitted a winch (another thread) and painted the rear x-member (maybe another thread there too) i discovered that my D90 300tdi overheates after just a few miles. Something it's never done before.I checked everything (well, I thought so at least) and tried every bleeding trick i could find on t'internet and in here. I came to the conclusion, that the thermostat had failed. With it removed the engine doesn't overheat. New one ordered and fitted and it overheated

I checked the guage with another, same, the engines overheating.
More emptying and filling, i'm sure theres no air in the system.
I changed the sensor too, that didn't help.
Without the thermostst it's fine, takes an age to get off cold and only gets up to 33% whereas it always sat @ 50%.

Any tips, hints or advice would be gratefully received.

Al2O3 · Jul 5, 2016

Do you think your water pump is working?

miktdish · Jul 5, 2016

Yes. With the engine ticking over the coolant fairly flies out the top up plug on the thermostst housing

Al2O3 · Jul 5, 2016

Is it flying out or bouncing/shaking out?
Any sign of water in oil or oil in water?

miktdish · Jul 5, 2016

flies out, deffinatley under pressure. No oil/water mix. Without the thermostat in no problem, no pressure in the overflow tank (well a little when hot, nothing more than expected).
New radiator 18 months ago, new pump, snake bely and pulleys 3 years ago ....

Any tips on checking the pump ??

flat · Jul 5, 2016

Could be coincidence but the thermostat could have been dodgy from new - it is known - try testing it in a pan of water using a regular thermometer

lynall · Jul 5, 2016

How are you bleeding it? 300 needs to be filled via the bung in the rad then refit header tank cap then carry on filling until rad is full, then fill via the stat bung then fit bung and away you go.
If its still playing up its head gasket time, not unheard of on the 300 and nearly always caused by a leaking p-gasket causing the level to get low and owner not noticing until its to late.

Kwakerman · Jul 5, 2016

If you have fitted a huge winch then it will also be restricting airflow through the radiator which won't help things. A good check of the coolant pump it to make sure the heater works (as it needs the pump to push water through it).

Dippypud · Jul 5, 2016

Is the rad getting hot all over ?
It may not be circulating well ...

mojo247 · Jul 5, 2016

sounds like it might be an airlock like I had in my 300tdi

the head will get cooked if it is overheating, so make sure the water's flowing properly through it!

like Kwakerman said, see if your heating is working, if it isn't then the water isn't flowing properly

Magicgrotto · Jul 5, 2016

Hi Mik
Are you getting any Air bubbles in the header tank When it's hot ?
If so it's your H/G

Steve

miktdish · Jul 5, 2016

Thanks for the replies. I'm coming to the conclusion that it's the water pump. The heater does get hot but I think the flow is weak. With the thermostat out the engine will warm up (to normal) after around 20 mins of driving. Yes the heater works (it's never been the hottest to be honest) but I can, by squeezing the top and bottom hoses, see a difference on the temperature guage.

Time to whip the pump off I think.
I was new 3 years ago and I think it was a Britpart ...

There seems to be several to choose from - any advice on manufacturer ??

Al2O3 · Jul 5, 2016

It's interesting that yours heats up to normal temperature, with stat out, after 20 mins. For years I suspected my stat was stuck open, because it took so long to warm up. Since the rebuild the temp gauge barely moves, even after 40 mins of constant driving, 30 mins of that at 55-60mph. I reckon my stat has been open all of this time, but the old rad, with most of the fins either missing or full of mud and dead flies, was not cooling efficiently! Now, with a brand new rad in, the temp gauge barely moves. About a week ago, it got up to a 'normalish' position, but it was gloriously sunny and about 20 degrees outside.

Kwakerman · Jul 5, 2016

Al2O3 said:
It's interesting that yours heats up to normal temperature, with stat out, after 20 mins. For years I suspected my stat was stuck open, because it took so long to warm up. Since the rebuild the temp gauge barely moves, even after 40 mins of constant driving, 30 mins of that at 55-60mph. I reckon my stat has been open all of this time, but the old rad, with most of the fins either missing or full of mud and dead flies, was not cooling efficiently! Now, with a brand new rad in, the temp gauge barely moves. About a week ago, it got up to a 'normalish' position, but it was gloriously sunny and about 20 degrees outside.

Having seen the difference between standard LR temp gauge and a full VDO installation (and checked with IR thermometer) I wouldn't place much trust in the LR one.

Al2O3 · Jul 5, 2016

Kwakerman said:
Having seen the difference between standard LR temp gauge and a full VDO installation (and checked with IR thermometer) I wouldn't place much trust in the LR one.

I know what you're saying

I did see it move on a hot day about 2 weeks ago! Drove 35 miles home last night at about 10 o'clock, raining, cold and dark. Needle never moved!
How much did you pay for the VDO gauge, about £40?

Kwakerman · Jul 5, 2016

Al2O3 said:
I know what you're saying I did see it move on a hot day about 2 weeks ago! Drove 35 miles home last night at about 10 o'clock, raining, cold and dark. Needle never moved!
How much did you pay for the VDO gauge, about £40?

This is the gauge I used (matches the others in my mud pod) and I think this was the sender. Pretty sure the 300 is 10x1mm thread, the connection is a bit of a pain because it is slightly recessed compared to the standard LR one (with the bullet connector), ended up making a short adaptor cable and used a spade socket with a 90 degree bend in it.

Al2O3 · Jul 5, 2016

Kwakerman said:
This is the gauge I used (matches the others in my mud pod) and I think this was the sender. Pretty sure the 300 is 10x1mm thread, the connection is a bit of a pain because it is slightly recessed compared to the standard LR one (with the bullet connector), ended up making a short adaptor cable and used a spade socket with a 90 degree bend in it.

Cheers, Kwakerman. I might add one of those to my wish list. I'll have to take the stat out and test it in a pan of hot water, though. I suspect it will be stuck open. Ok at the moment, but needs investigating before winter!

miktdish · Jul 6, 2016

Took the pump off. I can't see why it wasn't pumping, the impellers are still attached to the shaft which turns, albeit slightly stiffly (which I presume is the resistance from the seals ?). There are no signs of leaks and the gasket was in place.
The 3 x long bolts were each a different colour. The top one nicely zinc plated, the lower, very rusty and the other black, almost like a mix of old oil and exhaust carbon... I've decided to change the P gasket whilst i'm in there and DLS Landrover Spares are supplying an OE pump and both gaskets (nice chaps).

Still no real clue as to why the engine was overheating though ...

Kwakerman · Jul 6, 2016

miktdish said:
Took the pump off. I can't see why it wasn't pumping, the impellers are still attached to the shaft which turns, albeit slightly stiffly (which I presume is the resistance from the seals ?). There are no signs of leaks and the gasket was in place.
The 3 x long bolts were each a different colour. The top one nicely zinc plated, the lower, very rusty and the other black, almost like a mix of old oil and exhaust carbon... I've decided to change the P gasket whilst i'm in there and DLS Landrover Spares are supplying an OE pump and both gaskets (nice chaps).

Still no real clue as to why the engine was overheating though ...

Make sure you use the metal version of the P gasket and not the fibre / paper one otherwise you may be doing it again in a couple of years time.

Al2O3 · Jul 6, 2016

miktdish said:
Took the pump off. I can't see why it wasn't pumping, the impellers are still attached to the shaft which turns, albeit slightly stiffly (which I presume is the resistance from the seals ?). There are no signs of leaks and the gasket was in place.
The 3 x long bolts were each a different colour. The top one nicely zinc plated, the lower, very rusty and the other black, almost like a mix of old oil and exhaust carbon... I've decided to change the P gasket whilst i'm in there and DLS Landrover Spares are supplying an OE pump and both gaskets (nice chaps).

Still no real clue as to why the engine was overheating though ...

As Kwakerman suspected with mine, I wonder if your gauge or sender is faulty?

overheating confusion

Guns n Chainsaws

Well-Known Member

Guns n Chainsaws

Well-Known Member

Guns n Chainsaws

Well-Known Member

Well-Known Member

Well-Known Member

Never Knowingly Understood

Active Member

Well-Known Member

Guns n Chainsaws

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Guns n Chainsaws

Well-Known Member

Well-Known Member

Similar threads