Overheating - Page 2

SCP440 · 28th July 2022, 20:40

Could it just be a faulty thermostat? Easy to replace and if it has never been replaced would be one of the first things to try before spending big bucks.

oldie · 28th July 2022, 22:00

Checked the car today. No loss of water overnight. Fan comes on when A/c button pressed. Fan comes on occasionally when A/c turned off and driving, so assume (risky) it's (hopefully) not anything major and may have been more related to hot day hot engine and reversing for a minute =no air flow. Into garage tomorrow for a refill and see if anything forthcoming.

SD1too · 29th July 2022, 08:26

Quote:

Originally Posted by oldie

... may have been more related to hot day hot engine and reversing for a minute =no air flow.

You're right there David except that your radiator fan should have triggered and provided air flow. Best to check it.

Simon

dave lincs · 29th July 2022, 09:20

Quote:

Originally Posted by SD1too

David,

Reading your account the first thing to do, before reaching for your credit card, is to check that your radiator fan is working on both speeds using the "demist test".

Simon

Hi Simon

Just wondering if you could let me know how you test both fan speeds on a V8 using the demist test

Regards Dave

DeeJ · 29th July 2022, 10:47

Quote:

Originally Posted by trikey

I Dont wish to be the doom monger, but the V8 has been known to let go of a headgasket!

Highly unlikely though, really in the realms of "has been known". It's not a Rover engine, after all. Looking on the Two-Sixties shows only a handful of failures reported going back to 2006, and mostly explained by the obvious, like running dry of coolant, and two on supercharged engines.

David

BigRuss · 29th July 2022, 22:06

If it is losing coolant one place you can check is the inlet manifold. The rubber gaskets between the top alloy part and the plastic can leak, it's quite subtle and can be hard to spot

You need to check both sides.

The alloy corrodes and distorts the gaskets, in extreme cases it can crack the plastic

Good old OAT strikes again.

I've got one sat in my kitchen at the moment have got it all cleaned up and ready to re-assemble.

If anybody wants a spare inlet manifold give me a shout.

Russ

oldie · 30th July 2022, 21:42

Is there a way to test the fan other than to run the engine until it is up to temperature and see what happens? It comes on when I press the demise button, beyond that it's hard to tell because I'm behind the steering wheel driving the car.

SD1too · 31st July 2022, 07:05

Thanks for testing your fan's slow speed David.
The fast speed can be checked in the same way as for the other engines, by removing the trinary switch connector and joining the light green/red and black wires together provided that the V8's ECM allows it.

It would be more useful to activate the instrument pack diagnostics test no. 7.0 to monitor the engine's actual coolant temperature. The fan should start running at 99˚ and increase to fast speed if the coolant reaches 109˚C.

I suspect however that the unexpected overheating you experienced the other day was due to low coolant level of which you were unaware. Given that your fan is working on its first speed, I would continue to drive your car but check the coolant level on a cold engine every week. Ensure that the expansion tank is filled no higher than the MAX tab which should be visible by looking through the filler neck. If you can't see it your tank is overfilled and is liable to eject coolant which is what you don't want.

Please keep us up to date David.

Simon

dave lincs · 31st July 2022, 09:08

Hi David

I would not advise joining any of the wires together as most of the systems on the v8 cars are totally different, As Big Russ has said look for leak of coolant on the inlet manifold and any other parts you can see if you cant find anything keep checking the coolant level and see if it is dropping, As for checking the fan operation is there anyone local to you that has a T4 if so they can easily check the fan operation for you

Regards
Dave

oldie · 31st July 2022, 14:15

Fan definitely works on "demist". Absolutely no sign of life when up to temperature, engine running, parked. I would expect something, one of my long gone v6s did nothing but run on whether parked or driving - but that's another matter.

29th July 2022, 22:06	#16
BigRuss Premium Trader 75 CDT Tourer,2.5 Launch Saloon, Omipro MG/Rover (T4) Join Date: Jul 2007 Location: Liversedge, West Yorkshire Posts: 5,405 Thanks: 1,105 Thanked 1,340 Times in 661 Posts	If it is losing coolant one place you can check is the inlet manifold. The rubber gaskets between the top alloy part and the plastic can leak, it's quite subtle and can be hard to spot You need to check both sides. The alloy corrodes and distorts the gaskets, in extreme cases it can crack the plastic Good old OAT strikes again. I've got one sat in my kitchen at the moment have got it all cleaned up and ready to re-assemble. If anybody wants a spare inlet manifold give me a shout. Russ __________________ Replacement Key Service http://https://the75andztclub.co.uk/...d.php?t=244732 Full T4 Testbook diagnostics available. Diesel ECU repair and replacement. Options enabled or disabled as required. Diesel X-Power 135 and 160bhp, Rover 1.8T 150 to 160 MG 160 V6 to 177 upgrades available P.M. for details. Last edited by BigRuss; 29th July 2022 at 22:38..

31st July 2022, 07:05	#18
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,344 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	Thanks for testing your fan's slow speed David. The fast speed can be checked in the same way as for the other engines, by removing the trinary switch connector and joining the light green/red and black wires together provided that the V8's ECM allows it. It would be more useful to activate the instrument pack diagnostics test no. 7.0 to monitor the engine's actual coolant temperature. The fan should start running at 99˚ and increase to fast speed if the coolant reaches 109˚C. I suspect however that the unexpected overheating you experienced the other day was due to low coolant level of which you were unaware. Given that your fan is working on its first speed, I would continue to drive your car but check the coolant level on a cold engine every week. Ensure that the expansion tank is filled no higher than the MAX tab which should be visible by looking through the filler neck. If you can't see it your tank is overfilled and is liable to eject coolant which is what you don't want. Please keep us up to date David. Simon __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

28th July 2022, 20:40	#11
SCP440 I really should get out more....... MG ZT-T 260 Join Date: Feb 2016 Location: Witney Posts: 2,504 Thanks: 6 Thanked 910 Times in 571 Posts	Could it just be a faulty thermostat? Easy to replace and if it has never been replaced would be one of the first things to try before spending big bucks.

28th July 2022, 22:00	#12
oldie Loves to post Connoisseur SE v8 auto '54 Join Date: Jan 2009 Location: West Sussex Posts: 488 Thanks: 105 Thanked 56 Times in 41 Posts	Checked the car today. No loss of water overnight. Fan comes on when A/c button pressed. Fan comes on occasionally when A/c turned off and driving, so assume (risky) it's (hopefully) not anything major and may have been more related to hot day hot engine and reversing for a minute =no air flow. Into garage tomorrow for a refill and see if anything forthcoming.

30th July 2022, 21:42	#17
oldie Loves to post Connoisseur SE v8 auto '54 Join Date: Jan 2009 Location: West Sussex Posts: 488 Thanks: 105 Thanked 56 Times in 41 Posts	Is there a way to test the fan other than to run the engine until it is up to temperature and see what happens? It comes on when I press the demise button, beyond that it's hard to tell because I'm behind the steering wheel driving the car.

31st July 2022, 09:08	#19
dave lincs Posted a thing or two Rover 75 Saloon Join Date: Mar 2014 Location: Louth Posts: 1,409 Thanks: 380 Thanked 986 Times in 476 Posts	Hi David I would not advise joining any of the wires together as most of the systems on the v8 cars are totally different, As Big Russ has said look for leak of coolant on the inlet manifold and any other parts you can see if you cant find anything keep checking the coolant level and see if it is dropping, As for checking the fan operation is there anyone local to you that has a T4 if so they can easily check the fan operation for you Regards Dave

31st July 2022, 14:15	#20
oldie Loves to post Connoisseur SE v8 auto '54 Join Date: Jan 2009 Location: West Sussex Posts: 488 Thanks: 105 Thanked 56 Times in 41 Posts	Fan definitely works on "demist". Absolutely no sign of life when up to temperature, engine running, parked. I would expect something, one of my long gone v6s did nothing but run on whether parked or driving - but that's another matter.