T'stat problems?

Hi all, I've been reading a few threads here about overheating diesel P38s. I've had a problem that's been hanging around for ages with my 2.5DSE.

For nearly a year now, it's been the victim of sudden overheating. Over time (a year), every element of the cooling system has been replaced including the sensor. After each 'fix' it goes well for a good period and then, like last night, up it pops again. Currently, it heats up under load (high revs at speed or up long hills etc) and then returns to normal at a gentle cruise.

To me, this time it shows all the signs of a dodgy thermostat. Engine tested for potential head gasket issue just a month or so ago. This time, I'm going to assume the t'stat has gone as it seems to have all the symptoms of that as a fault but I suspect the typical 'Britpart' replacement might not be wise this time.

Does anybody recommend an alternative type/manufacturer?

Thanks in advance,

D

OEM Stat, check the viscous fan and water pump as well the plastic impellers come loose on the shaft.

Or a radiator with no centre baffle.

Datatek said:

OEM Stat, check the viscous fan and water pump as well the plastic impellers come loose on the shaft.

Click to expand...

Data if the impeller is loose would it completly stop pumping or would it be reduced flow?

gfromleeds said:

Data if the impeller is loose would it completly stop pumping or would it be reduced flow?

Click to expand...

Reduced or no flow and it could switch from one to the other at random When replaceing, buy the metal impeller version.

My car has the same problem at the moment but once it heats up the heaters stop blowing hot air and so the temperature goes fully in to the red

Brand new thermostat & water pump fitted 2 weeks ago

m444lyx said:

My car has the same problem at the moment but once it heats up the heaters stop blowing hot air and so the temperature goes fully in to the red

Brand new thermostat & water pump fitted 2 weeks ago

Click to expand...

Diesel or petrol? Either an airlock, duff RAD, STAT or Viscous fan. Lots of faulty new stats about, always test before fitting.
Heater stops blowing hot because it's steam locked due to the overheat.
If it's a diesel a cracked head will happen if it continues to overheat even if that has not already happened.

damlimey.

I would recommend a LR stat. check its operation before you put it in also.
You can compare it to your old one at the same time.
I keep my old one which I have modified to have no internals, just in case I have trouble when out and about.
Your new water pump I hope had metal vanes in it. so that should be fine.

It would be worth doing Datatek air con fans nod and then you can take your viscous fan off. this also then opens up access to stat and waterpump for on the road running repairs.

Lastly. The radiator. when you put the new one in did you check for the baffle in the top header tank? If not then you need to. Many many are supplied without this!

Best of luck. and in the mean time make sure you don't cook it!
regards.

Firstly, thank you guys for your quick responses & for taking the time out to get back to me so quick!

As for the car, when I bought the vehicle I checked it over best I could, there was no oil & water or water & oil mixing, I test drove it about a mile checked all the gears and the air suspension + heaters etc (everything you would do when buying a used car) eventually I was happy with it we did the deal and 3-4 miles down the road up a big steep hill the temp shot up and went in to red, I stopped blasted the heaters on full but no luck, temp was staying there - I got the vehicle recovered home - took it on 4-5 test runs and noticed an improvement after changing the thermostat but again when floored or under pressure vehicle would overheat and temp would only come down slightly with heaters on but if the heat was on red temp would not come back down and lots and lots of pressure in the coolant tank and the pipes become red hot.

I am worried that the previous owner may have already cooked it or cracked the head, its a diesel & I know this is a common problem - now my dilema is do I cut my losses and sell on or through more money at it?

My trusty mechanic has been over it a few times and thinks its the headgasket.. 2 other indys have also both said this, there is a local land rover specialist about 2 miles away from my house but the other issue we have is key code lockout as the vehicle has been parked the best part of 6 weeks now and I took the battery out for charging


Thanks for your help guys!

donp38 said:

damlimey.

I would recommend a LR stat. check its operation before you put it in also.
You can compare it to your old one at the same time.
I keep my old one which I have modified to have no internals, just in case I have trouble when out and about.
Your new water pump I hope had metal vanes in it. so that should be fine.

It would be worth doing Datatek air con fans nod and then you can take your viscous fan off. this also then opens up access to stat and waterpump for on the road running repairs.

Lastly. The radiator. when you put the new one in did you check for the baffle in the top header tank? If not then you need to. Many many are supplied without this!

Best of luck. and in the mean time make sure you don't cook it!
regards.

Click to expand...

I have not replaced the radiator, my mechanic took out the viscous fan - I would like to point out the fan always runs as soon as you start the car and it is pretty slow - I dont know if this is normal (its my first range rover)

Ironically I bought it to do a matte black project & now im left with a mechanical one, lol

The waterpump was supplied by eurocarparts (i'm told by my mechanic the old waterpump was ok)

I called AA & demanded a hgf chemical test & pressure test which they carried out a few weeks ago and the problem was diagnosed as faulty water pump due to lack of pressure/compression & the chemical test showed headgasket was ok BUT he did it while the car was off which dosn't make sense?

m444lyx said:

I have not replaced the radiator, my mechanic took out the viscous fan - I would like to point out the fan always runs as soon as you start the car and it is pretty slow - I dont know if this is normal (its my first range rover)

Ironically I bought it to do a matte black project & now im left with a mechanical one, lol

The waterpump was supplied by eurocarparts (i'm told by my mechanic the old waterpump was ok)

I called AA & demanded a hgf chemical test & pressure test which they carried out a few weeks ago and the problem was diagnosed as faulty water pump due to lack of pressure/compression & the chemical test showed headgasket was ok BUT he did it while the car was off which dosn't make sense?

Click to expand...

If you can stop the viscous fan with a rolled up news paper when the engine is hot, it's shot. Do my aircon fans mod.
Silted up RAD's are also a common problem due to the stupid flow arrangement, check it gets hot all over evenly.
HGF is pretty rare, a cracked head is much more common if it's been overheated.

Right, I take it I should start with a LR thermostat then..

What I have been told is that if thermostat is causing the problem, once its been removed completely the vehicle should not overheat - otherwise the thermostat is not the problem - is that correct?

Also the fan is a steady speed the last time I tried to stop it was with my hand and it kept going..

Should I get a new rad first?

can you send me a link to your air con fan mod please

The other thing I dont get is on the rare occasion when the engine actually is running, it sounds spot on & drives pretty well, even the power seems like its there..


It can be hard to start sometimes & take lots of cranks..... Usually the first time you start it in the morning its fine and then after that you really have to hold the key

m444lyx said:

Right, I take it I should start with a LR thermostat then..

What I have been told is that if thermostat is causing the problem, once its been removed completely the vehicle should not overheat - otherwise the thermostat is not the problem - is that correct?

Also the fan is a steady speed the last time I tried to stop it was with my hand and it kept going..

Should I get a new rad first?

Click to expand...

Check the RAD gets hot all over.

m444lyx said:

can you send me a link to your air con fan mod please

Click to expand...

PM me with an email address.

m444lyx said:

The other thing I dont get is on the rare occasion when the engine actually is running, it sounds spot on & drives pretty well, even the power seems like its there..


It can be hard to start sometimes & take lots of cranks..... Usually the first time you start it in the morning its fine and then after that you really have to hold the key

Click to expand...

Hot start problems are well known, there is a "Hot Start Fix" to get round it, assuming it's not a sensor problem. Really needs a look on diagnostics.