overheating issue
Discussion
have just replace my 4.0 v8 for a 4.5 v8, ( the engine came from a car that had only done 29000 mile) I now have an issue with it over heating at speed, all the cooling system had been drained and the rad replaced as it had a number of cold spots. There does seem to be a miss fire on cylinder 3.
Any help that can be supply will be most greatful
Any help that can be supply will be most greatful
on the cooling front what have you done so far ?
Top off swirl pot is it full to the brim ? Likewise the header tank, what level is is sat at ? Has the cooling system been bled using one of the documented methods (see the bible or search on here) ?
What are the symptoms when it overheats - what does the guage go up to , are the fans kicking in ?
Oh and is the thermostat working ?
misfire - check HT leads and extended for a start.
Im a tinkerer not an expert but these are the things I'd be checking first.
Top off swirl pot is it full to the brim ? Likewise the header tank, what level is is sat at ? Has the cooling system been bled using one of the documented methods (see the bible or search on here) ?
What are the symptoms when it overheats - what does the guage go up to , are the fans kicking in ?
Oh and is the thermostat working ?
misfire - check HT leads and extended for a start.
Im a tinkerer not an expert but these are the things I'd be checking first.
I'm just another tinkerer, but I was being followed by a 5 litre Chim this morning, and after 20 miles at 60, we stopped at the lights for the first time and I noticed I could hear his fans cut in. My car was still reading 75 degrees on the useless TVR temperature gauge. I asked him about it when we stopped and he just said "I know", meaning I guess that his 5 litre, high output engine, had the fans set to cut in at a lower temperature to avoid overheating.
Another Chim owner, Alex, mentioned to me that you cannot trust the temperature gauge, but that you could fit something else in place of the standard sensor so that you know the true picture. Alex? What should he do?
Another Chim owner, Alex, mentioned to me that you cannot trust the temperature gauge, but that you could fit something else in place of the standard sensor so that you know the true picture. Alex? What should he do?
IME as long as the cooling system is all ok then you wont suffer overheating. I've sat in crawling traffic for >1 hour with no overheating problems in my 450. Just make sure the correct thermostat and otter switch are fitted, coolant is up to the right level and your rad isnt knackered.
Plenty of people fit lower temp otter switches or thermostats or fiddle with things which IMHO just masks whatever problem is causing the overheating in the first place. If there is a problem fix the cause rather than just masking it.
Dash gauge is really only an indicator. Get used to what it usually reads , then if it does something unusual you know you have a problem. Mine typically reads around 70 , but the engine temp sensor that the ECU reads is returning the correct temp, my thermostat opens at the correct temp and my otter kicks the fans in at the right time too (thanks to the ECUmate for letting me see all this in action)
Plenty of people fit lower temp otter switches or thermostats or fiddle with things which IMHO just masks whatever problem is causing the overheating in the first place. If there is a problem fix the cause rather than just masking it.
Dash gauge is really only an indicator. Get used to what it usually reads , then if it does something unusual you know you have a problem. Mine typically reads around 70 , but the engine temp sensor that the ECU reads is returning the correct temp, my thermostat opens at the correct temp and my otter kicks the fans in at the right time too (thanks to the ECUmate for letting me see all this in action)
jimbo1812 said:
well the issue seem to be that the expansion tank wants to dump coolant when running at high speed. The fan kicking at the correct temp as you can hear them cutting. Does anyone know if the miss fire would pressurize the system that much that it want to dump the coolant?
Oh dear oh dear oh dear - I *hope* I'm wrong but this is exactly the sort of thing consistent with head gasket failure. Heat/exhaust escaping from the cylinder across the broken gasket into the water jacket boils your water giving the high pressure you complain of. It could also be a slipped liner/porous block that I believe V8 Racing advised in your earlier thread.Where did this engine come from? Was it of know good quality? There is often a reason that engines aren't in cars anymore!
Of course it could just be that you have overfilled the expansion tank. They are not designed to be run full - some vary but around 2 inches from the bottom when cold is the fill level. Any more than that then it will vent out when hot.
Again - I hope I'm wrong but my hunch is that someone has sold you an engine with a problem that they 'probably' knew about
can you elaborate on this which you posted up in your 'replacement engine' thread minding not to name any names.
jimbo1812 said:
I have just got a second hand 4.5 engine(after talking to other TVR specialist in my area and who how used the company that I got the engine from) that has done 29,000 mile as the engine builder that i has found wouldn’t let the local TVR specialist that i use to fit the engine, thus would not provide any warranty on it.
I think the mis-fire needs to be diagnosed properly and quickly, especially if you dont know the full history of the engine. As mentioned above, this may resolve the overheating problems and quick diagnosis prevent more serious damage.
If it is purely a cooling system thing then I would check the rad thoroughly for any leaks/water stains. A few rads have had leaks within the side casings and the tell tale water trickle marks are hidden from view. A re-core is not too expensive. Also check the expansion tank cap fits snug and holds pressure and also that the otter switch (sticking out of the rad) is working correctly. They cost £20 and my car runs a good 5oC cooler for just changing this and keeping those fans running longer when hot. And if you fill the expansion tank to the top it will spit water out everywhere.
Bit strange how the car overheats at speed, it's usually sitting in traffic with no airflow into the engine bay.
Hope it's nothing horrible.
If it is purely a cooling system thing then I would check the rad thoroughly for any leaks/water stains. A few rads have had leaks within the side casings and the tell tale water trickle marks are hidden from view. A re-core is not too expensive. Also check the expansion tank cap fits snug and holds pressure and also that the otter switch (sticking out of the rad) is working correctly. They cost £20 and my car runs a good 5oC cooler for just changing this and keeping those fans running longer when hot. And if you fill the expansion tank to the top it will spit water out everywhere.
Bit strange how the car overheats at speed, it's usually sitting in traffic with no airflow into the engine bay.
Hope it's nothing horrible.
See if you can get hold of an ECUmate - It reads the engine temp from the ECU sensor rather than the temp gauge sensor so its much more accurate. Using mine I could see the temp rise , then drop as the thermostat opened then rise again until the fans cut in, all at exactly the temps they were supposed to. Gave me a lot more confidence that the cooling system was working properly and that the gauge really was lying.
ETA where in oxfordshire are you, I may be able to drop in with my ECUmate and see if it can tell you anything plus I have some spare plug extenders so could eliminate that as a possible cause of the misfire. PM me.
ETA where in oxfordshire are you, I may be able to drop in with my ECUmate and see if it can tell you anything plus I have some spare plug extenders so could eliminate that as a possible cause of the misfire. PM me.
peaktorque said:
A compression test wouldn't hurt.
Simon says said:
along with a Hydrocarbon test on that cooling system 
better still a leak down test on the mis-firing cylinder which hopefully wont show up as bubbles in the cooling system 
Sound advice from the the guys above.
I think that checking the basics as mentioned previously which can be done in a couple hours:
1 - Fan Otter switch
2 - ECU Coolant Temp sensor
3 - A good look at the Rad
Then getting a decent garage to carry out a couple tests will pay dividends.
1 - Hydrocarbon Test
2 - Compression/Leak down test on suspect cylinder
You've had a look under the oil filler cap right? No nasty white mayonnaise like goo in there?
If so then something is certainly up but a lack of it doesn't mean it's all fine as a leaking HG can give no oil in the water and vice versa
Really not trying to give you all doom and gloom but I've been down a similar road myself (not with a TVR - an MGB as it happens) and got ripped off by another garage who put a dodgy lump in.
The whole time I was kidding myself that there was nothing wrong and it would sort itself out and was probably because the carbs weren't jetted right etc etc - in the end it blew the HG big style on the M4 about 6 weeks after the engine it was fitted. Sometimes you just get a feeling for these things. Hope it's not the case with yours.
Keep us posted on how you get on and good luck!
debaron said:
peaktorque said:
A compression test wouldn't hurt.
Simon says said:
along with a Hydrocarbon test on that cooling system better still a leak down test on the mis-firing cylinder which hopefully wont show up as bubbles in the cooling system Sound advice from the the guys above.
I think that checking the basics as mentioned previously which can be done in a couple hours:
1 - Fan Otter switch
2 - ECU Coolant Temp sensor
3 - A good look at the Rad
Then getting a decent garage to carry out a couple tests will pay dividends.
1 - Hydrocarbon Test
2 - Compression/Leak down test on suspect cylinder
You've had a look under the oil filler cap right? No nasty white mayonnaise like goo in there?
If so then something is certainly up but a lack of it doesn't mean it's all fine as a leaking HG can give no oil in the water and vice versa
Really not trying to give you all doom and gloom but I've been down a similar road myself (not with a TVR - an MGB as it happens) and got ripped off by another garage who put a dodgy lump in.
The whole time I was kidding myself that there was nothing wrong and it would sort itself out and was probably because the carbs weren't jetted right etc etc - in the end it blew the HG big style on the M4 about 6 weeks after the engine it was fitted. Sometimes you just get a feeling for these things. Hope it's not the case with yours.
Keep us posted on how you get on and good luck!
jimbo1812 said:
The system has been tested by the TVR specialist that i have taken it to and it seems that there is a crack behind the liner on cylinder 3, as when the engine is cold it will only fire on 7 of the cylinders and not all 8, when warn it cylinder 3 over pressurizes and cause the expansion tank to dump the coolant. I’m spoken to the people that I got the engine from to see what can be doen and they are also in talks with the specialist as well. Let hope we agree on an outcome, otherwise she will be off the road for a while :-(
Sorry to hear it mate. These engines (4.6 in particular) are known for it.I'd be having serious words with the people who supplied you with the engine. Anyone who halfway knows Rover V8's will have know about this problem.
They'll probably blame the people who fitted it and say 'it's overheated since we supplied it - that's whats caused it' and 'it was fine when we gave it to you' etc etc....
Short answer is you are looking at another block/engine which is a total PITA or, if you plan on keeping the car - Top Hat liners
See here:
http://www.v8developments.co.uk
They are the ultimate in sorting this problem once and for all and is what Rover should have done in the first place with these engines.
Not cheap (not too bad though) and you'll never have to worry about leaking liners again. It's the only way to go!!
PM if you need any further advice - again sorry to hear it.
debaron said:
jimbo1812 said:
The system has been tested by the TVR specialist that i have taken it to and it seems that there is a crack behind the liner on cylinder 3, as when the engine is cold it will only fire on 7 of the cylinders and not all 8, when warn it cylinder 3 over pressurizes and cause the expansion tank to dump the coolant. I’m spoken to the people that I got the engine from to see what can be doen and they are also in talks with the specialist as well. Let hope we agree on an outcome, otherwise she will be off the road for a while :-(
Sorry to hear it mate. These engines (4.6 in particular) are known for it.I'd be having serious words with the people who supplied you with the engine. Anyone who halfway knows Rover V8's will have know about this problem.
They'll probably blame the people who fitted it and say 'it's overheated since we supplied it - that's whats caused it' and 'it was fine when we gave it to you' etc etc....
Short answer is you are looking at another block/engine which is a total PITA or, if you plan on keeping the car - Top Hat liners
See here:
http://www.v8developments.co.uk
They are the ultimate in sorting this problem once and for all and is what Rover should have done in the first place with these engines.
Not cheap (not too bad though) and you'll never have to worry about leaking liners again. It's the only way to go!!
PM if you need any further advice - again sorry to hear it.
Top hats all the way 
Sorry to hear about the engine Jimbo I had doubts when I read the misfiring and pressurising the cooling system bit hope you get a good outcome 
i'm getting prices from
V8 development
JE Development
Oselli engineering
Lloyd Special Development
As the engine is low milage anyway and i'm going to keep her so top hat liners, as has been said is the way to go
i'm waiting to here from the guys that i got the engine from not holding out much hope :-(, so will not be using them for part etc any more :-)
V8 development
JE Development
Oselli engineering
Lloyd Special Development
As the engine is low milage anyway and i'm going to keep her so top hat liners, as has been said is the way to go
i'm waiting to here from the guys that i got the engine from not holding out much hope :-(, so will not be using them for part etc any more :-)
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