overheating - thermostat

JD · Jun 7, 2011

Probably not being much help here, and I know you said you tried bleeding at an angle but not which direction...but one thing I did was have the car facing uphill on a pretty steep incline so the top of the rad is higher than the top hose, seemed to me if there was any air in the system the only place it had to go was out of the overflow and into the expansion tank.

ⓡⓤⓓⓨ · Jun 7, 2011

JD. said:
Probably not being much help here, and I know you said you tried bleeding at an angle but not which direction...but one thing I did was have the car facing uphill on a pretty steep incline so the top of the rad is higher than the top hose, seemed to me if there was any air in the system the only place it had to go was out of the overflow and into the expansion tank.

I've just tried that, but no luck.
I also noticed that the top hose doesn't seem to get any water to it

I even filled it from the top hose as well as the exp bottle but the hose stays empty...
I initially thought it did as it went hot, but that was just caused by steam I guess.....

So no water to top hose = waterpump kaput?

fanatic · Jun 7, 2011

Possible.
I'd also look for rusty spark plugs, have you had any spluttering or un even starting in mornings?

ⓡⓤⓓⓨ · Jun 7, 2011

fanatic said:
Possible.
I'd also look for rusty spark plugs, have you had any spluttering or un even starting in mornings?

No rusty spark plugs at all and starts first turn of the key with no spluttering

fanatic · Jun 7, 2011

Have you poked the small pipe on radiator top?
Loosen top hose and try filling, sometimes air locks can be removed this way.

You don't have LPG do you?

bigwill · Jun 7, 2011

complete rr amateur, got a 95 4.0 she runs fine you can thrash and thrash but sometimes you get a split second of overheat warning on the comp, and then it goes away. if you let her idle after cold start she heats up to a point where touching the bonnet is painfully hot all the pipes/hoses are hot as f*** (including the bottom hoses) collent is at a normal level, no dramatic happenings other than the heat. any ideas??

didnt mean to steal the thread, just thought whilst people are on the topic!

ⓡⓤⓓⓨ · Jun 7, 2011

fanatic said:
Have you poked the small pipe on radiator top?
Loosen top hose and try filling, sometimes air locks can be removed this way.

You don't have LPG do you?

No LPG

I've poked and squeezed about everything and also filled it with the top hose off....no joy

fanatic · Jun 7, 2011

I'd be tempted to get a hydro carbon sniff test with a gas analyser done, or you could take off water pump and examine it.

fortgrange · Jun 7, 2011

I've had several issues with non genuine thermostats. 1 leaked around the plastic housing after about 1k miles, replaced with another non genuine which wouldn't open correctly. Bit the bullet and stumped up for a genuine one and have had no issues since, that was about 6 months and 5k miles ago. I realise you said you tested before fitting but mine appeared to be working when off the vehicle but just wouldn't open correctly when fitted.

I should point out that I did think I was fitting the genuine artical at first because they were about £25 each, but realised they weren't when I paid £60 for a genuine one

ⓡⓤⓓⓨ · Jun 7, 2011

fanatic said:
I'd be tempted to get a hydro carbon sniff test with a gas analyser done, or you could take off water pump and examine it.

Might be an idea....but how would a blown HG or similar cause the stat to not open or not let water to the top hose?

In my opinion the system is not over-pressurising at all, oil is clean as can be and water is chrystal clear...

fanatic · Jun 7, 2011

ⓡⓤⓓⓨ;1523020 said:
Might be an idea....but how would a blown HG or similar cause the stat to not open or not let water to the top hose?

In my opinion the system is not over-pressurising at all, oil is clean as can be and water is chrystal clear...

Head gasket failure or liner failure the exhaust gases can cause like air lock and cause odd circulation faults. It would just clearly prove you have a circulation issue NOT HGF if it comes back negative.

clarkie · Jun 7, 2011

if you still have the old stat knock the middle out of it so its allways open and try that, it will take about 10 miles for it to overheat from cold like this,it did with mine,oil and water dont mix with a cracked block,you could bodge it with irontite or k-seal but this still may not work,if none of the above work start looking for a replacement engine as i had to,its all fun with a p38

ⓡⓤⓓⓨ · Jun 7, 2011

clarkie said:
if you still have the old stat knock the middle out of it so its allways open and try that, it will take about 10 miles for it to overheat from cold like this,it did with mine,oil and water dont mix with a cracked block,you could bodge it with irontite or k-seal but this still may not work,if none of the above work start looking for a replacement engine as i had to,its all fun with a p38

I just did that - fitted the old, 'modified' stat. Haven't taken it for a spin yet though. Will do in a minute and report back!

ⓡⓤⓓⓨ · Jun 7, 2011

Just drove 20 miles HARD! Temp gauge stays bang on in the middle and runs slightly back when idle.

I did not completely jam open the old stat, just a little. Seems that does the trick.
The most important part - It didn't overheat

jt_armstrong · Jun 7, 2011

ⓡⓤⓓⓨ;1521998 said:
I've flushed the radiator - perfect flow
Inspected the bottle for hairline cracks - all fine

Waterpump is something I am going to check tomorrow. I have been thinking this myself since a core plug was missing (possibly through ice in block) it is very possible that they have tried to start the engine while frozen and sheared off the impeller......Just a theory

Another thing -- would a faulty water pump only cause it to overheat while driving?

Your theory is good. I did that very thing last November. Caused me no end of heartache.

ⓡⓤⓓⓨ · Jun 7, 2011

ⓡⓤⓓⓨ;1523316 said:
Just drove 20 miles HARD! Temp gauge stays bang on in the middle and runs slightly back when idle.

I did not completely jam open the old stat, just a little. Seems that does the trick.
The most important part - It didn't overheat

Since it does not overheat now...does that rule out a cracked block or other doom stories?

jonbill · Jun 7, 2011

I hope you're right, but I'd still be keeping my eye on the temp gauge.
I wonder if having a hole in the stat helps bleed it when the water is cold?

fanatic · Jun 7, 2011

jonbill said:
I hope you're right, but I'd still be keeping my eye on the temp gauge.
I wonder if having a hole in the stat helps bleed it when the water is cold?

It is common to remove thermostat to hide head gasket.

While you may have a faulty stat, the problems bleeding it and steam are cause for concern.

I have suggested a test that is extremely accurate at ruling out HGF. a modern gas analyzer detects hydrocarbon parts per million.
Far superior to liquid test.

But the other choice is pull the water pump off and look

vougese39 · Jun 7, 2011

Having read all the posts here are a few ideas.
One I use a vacuum coolant fill system which sucks all the air from the cooling system when you have drained it with it having a gauge I can leave and watch for a drop in vacuum which them informs me I have a leak which requires investigating but if the gauge does not drop then I turn a tap and the vacuum in the cooling system draws in the new coolant and primes the cooling system which 99% eliminates the possibility of a air lock!
Two as you have forced the state open one can assume the fault is the state and yes the cheap states are not wormy the monsy I only fit gen ones on my rebuilt engines.
Three water pump as mentioned
Four the last and the simplest one which is over looked you can safely run the v8 without the cooling fan and this allows you to check the rad for cold spots which denote blocks and coolant flow too

ⓡⓤⓓⓨ · Jun 8, 2011

Thanks for the all the replies guys, much appreciated

Upadate:

Took the RR for an MOT test this afternoon and FAILED

Luckily it only failed on 1 tyre and a track rod end, so not too bad

It also turns out my overheating issue is not fixed!

The drive to the MOT station (a 10 mile combo of dual track road and town driving) went perfect, no temp issues at all. Car was running for the entire MOT test and was taken out for a 10-15min brake run at the end with no issues. On the way back, about 1 minute from home - It overheated again and water was p*ssing out the exp tank again

overheating - thermostat

New Member

Active Member

RESPECT IS EARNED, BEATINGS ARE FREE ;-)

Active Member

RESPECT IS EARNED, BEATINGS ARE FREE ;-)

Active Member

Active Member

RESPECT IS EARNED, BEATINGS ARE FREE ;-)

Active Member

Active Member

RESPECT IS EARNED, BEATINGS ARE FREE ;-)

Active Member

Active Member

Active Member

Well-Known Member

Active Member

New Member

RESPECT IS EARNED, BEATINGS ARE FREE ;-)

Well-Known Member

Active Member

Similar threads