How to get a cooler running engine / stop rattling when hot?
Discussion
My 4.0 engine seems to get quiet hot when not driving like a granny.... temperatures then raise to 100 degree for water and 110 degree for oil, not matter what time of the year. Fans both kick in at about 95 to 100... but unless I step off the throttle temps will stay hot.
Main issue about the high temps is, that the engine brutally rattles (or knocks) once oil reaches about 95 degree. This is independent from the water temperature. Tested it today... rattle started when hot. Both temp levels were at about 100 degree... then water cooled down to 85 but oil still was 98. Still rattling. Once oil temps dropped below 95, rattling slowly vanished again. Then I made the water get hotter again.... Water at 102 degree, oil still 91... no rattling.
Besides the fact, that there should be no loud rattling at those temperatures, I have the feeling that my engine runs to hot, compared to most of the values I read on the forums, that tend to be in the range of 70 to 95 degree under all conditions!?
Some more facts:
Shims all measured and ok
Camshaft / fingerfollowers all ok
No water leaks, level ok
All sorts of oil tested from 5w-40 to 10-w60 (current)
Using 95 octane fuel
Compression ok
Using standard NGK plugs for SP6 engines
Does not matter if accelerating/decelerating or ideling... even though it sometimes seem to not sound so bad when slowly going up from 900 to 1200 rpm
I somehow have the feeling that it might be related to a to high burning temperature that results in either detonations or pre-ignition!?
What can cause the high temps? And what additional things can I do to cool down the engine like using colder spark plugs?
Can a faulty lambda cause higher burning temps? (will read out their values this weekend)
And would it damage the engine to run it shortly with one spark plug detached?... to see if the knocking comes from one specific cylinder?
Main issue about the high temps is, that the engine brutally rattles (or knocks) once oil reaches about 95 degree. This is independent from the water temperature. Tested it today... rattle started when hot. Both temp levels were at about 100 degree... then water cooled down to 85 but oil still was 98. Still rattling. Once oil temps dropped below 95, rattling slowly vanished again. Then I made the water get hotter again.... Water at 102 degree, oil still 91... no rattling.
Besides the fact, that there should be no loud rattling at those temperatures, I have the feeling that my engine runs to hot, compared to most of the values I read on the forums, that tend to be in the range of 70 to 95 degree under all conditions!?
Some more facts:
Shims all measured and ok
Camshaft / fingerfollowers all ok
No water leaks, level ok
All sorts of oil tested from 5w-40 to 10-w60 (current)
Using 95 octane fuel
Compression ok
Using standard NGK plugs for SP6 engines
Does not matter if accelerating/decelerating or ideling... even though it sometimes seem to not sound so bad when slowly going up from 900 to 1200 rpm
I somehow have the feeling that it might be related to a to high burning temperature that results in either detonations or pre-ignition!?
What can cause the high temps? And what additional things can I do to cool down the engine like using colder spark plugs?
Can a faulty lambda cause higher burning temps? (will read out their values this weekend)
And would it damage the engine to run it shortly with one spark plug detached?... to see if the knocking comes from one specific cylinder?
I would agree, use ONLY 98.
Some say, the water temp gauge is not accurate compared to the sensor of the ecu. On my engine temperatures are too high in my point of view. The engine is "new" and I got an alloy radiator. The ECU should start the first fan at 92, the 2nd at 94 and go off at 88 degrees. In other words water should stay at 90.
The oil temp always lags a bit behind the water temps, but should not go to 100.
If I understand you, the engine rattles at any rpm when the oil reaches 95 ?
Check what the ECU tells you.
Some say, the water temp gauge is not accurate compared to the sensor of the ecu. On my engine temperatures are too high in my point of view. The engine is "new" and I got an alloy radiator. The ECU should start the first fan at 92, the 2nd at 94 and go off at 88 degrees. In other words water should stay at 90.
The oil temp always lags a bit behind the water temps, but should not go to 100.
If I understand you, the engine rattles at any rpm when the oil reaches 95 ?
Check what the ECU tells you.
95 octane fuel is not good for speed six engines. By law they have to be able to run on it, but they will pink when hot. There's a reason why Dom specifies all his rebuilt engines must only be run on 98+ octane fuel, and he doesn't alter the compression ratio.
Regards temps, see what temps the ECU is reading as they're the ones that matter. The temp readings on the pod come from a totally different sensors so may be misreading.
Regards temps, see what temps the ECU is reading as they're the ones that matter. The temp readings on the pod come from a totally different sensors so may be misreading.
Still searching my data cable.... but as fans kick in at 94/96 dash temps, this means there is just a 2 degree difference to the ecu readings. But will verify as soon as I dig up that cable.
Sewing machine noise is present at any RPM as soon as oil temp reaches 95 degree. Noise sometimes silences a bit when using the throttle pedal up/down in the 900 rpm range. So thought could be a bearing problem when oil gets thin... but regarding to a lotus engine guy, symptoms for that would be different.
Flushed the fuel system today and refilled it with 100 octane gas.... no difference.
Drove a couple of hours... also switched on the cooling fans to run permanently.... what helped keeping the water below 90 degrees... but oil temp at some point reached again the critical temp.
Was driving very relaxed.. no speeding... temps where fine (with fans on)... then heavily accelerated a few times and oil temp went up nearly instantly to 95 and above, while water still was fine.
And as water stayed cooler, I guess the thermostat is fine!?
But will still get it out to test it and bleed the system.... as there are not many options left that could cause it!?
And I definitely need to read all the ecu data about the lambdas, temps etc... even though I do not fully understand the readings and displays yet...
...and what I really would like to try is to run the engine shortly with one spark plug cable pulled, to see if a specific cylinder is causing the rattling... just need to know if there is a danger when doing this for some seconds?
Sewing machine noise is present at any RPM as soon as oil temp reaches 95 degree. Noise sometimes silences a bit when using the throttle pedal up/down in the 900 rpm range. So thought could be a bearing problem when oil gets thin... but regarding to a lotus engine guy, symptoms for that would be different.
Flushed the fuel system today and refilled it with 100 octane gas.... no difference.
Drove a couple of hours... also switched on the cooling fans to run permanently.... what helped keeping the water below 90 degrees... but oil temp at some point reached again the critical temp.
Was driving very relaxed.. no speeding... temps where fine (with fans on)... then heavily accelerated a few times and oil temp went up nearly instantly to 95 and above, while water still was fine.
And as water stayed cooler, I guess the thermostat is fine!?
But will still get it out to test it and bleed the system.... as there are not many options left that could cause it!?
And I definitely need to read all the ecu data about the lambdas, temps etc... even though I do not fully understand the readings and displays yet...
...and what I really would like to try is to run the engine shortly with one spark plug cable pulled, to see if a specific cylinder is causing the rattling... just need to know if there is a danger when doing this for some seconds?
There is probably no one who will confirm it's ok to run the engine on 5 cylinders. I don't how bad the rattling is, but if you pull a plug on a running engine it will shake and I doubt if you can find the source of the noise then. However it's your engine and it won't break apart if you pull the plug (or the injector connector) for a short moment on idle.
I'm thankful for any hint... and even if the engine would fall apart, I would not blame anyone for giving risky tips. At the end it's me deciding to do it.... and I will do anything needed to find the source! Already have that issue for more than a year and it's getting really annoying as it seems to be unidentifiable. And the noise is REALLY loud!... like a sledgehammer hitting the engine with every or every second cycle. People do not turn their heads because of the normally beautiful sound but because they are afraid of getting hit by a giant sewing machine.
I will try all things mentioned here... and if it fails I will probably bring it to some far far away TVR guy to listen to the sound and hopefully pin down the problem. Unfortunately Germany is a TVR service wasteland.
After checking ecu data, bleeding the cooling system and checking the thermostat I might record the sound if not gone by then.
I will try all things mentioned here... and if it fails I will probably bring it to some far far away TVR guy to listen to the sound and hopefully pin down the problem. Unfortunately Germany is a TVR service wasteland.
After checking ecu data, bleeding the cooling system and checking the thermostat I might record the sound if not gone by then.
A s6 engine, driven normally and not hard, will run on good 95 octane fuel without pinking. If you're going to drive it let's say...enthusiastically then 98.
A good test to see if it's running on all 6 is start the engine and let it run for a few minutes and then try a cable tie against the manifolds, they should all melt the tie, the one not firing will not.
What oil are you using, how old is it? Oil cooler not functioning??
A good test to see if it's running on all 6 is start the engine and let it run for a few minutes and then try a cable tie against the manifolds, they should all melt the tie, the one not firing will not.
What oil are you using, how old is it? Oil cooler not functioning??
Edited by TVR_owner on Sunday 7th July 10:47
If you're trying to locate to the noise, is it rather from the top front ?
As far I know, the tolerances from the chains running on the cam sprockets to the inside of the cam cover are tiny. Maybe due to temperature (and enlargement of the chains) they may touch the inside of the cam cover ?
Maybe you find an S6 owner in your area in the german tvcc section ?
There are some who have good knowledge of the S6 engine, and there is at least one company having rebuilt more than one s6 engine.
As far I know, the tolerances from the chains running on the cam sprockets to the inside of the cam cover are tiny. Maybe due to temperature (and enlargement of the chains) they may touch the inside of the cam cover ?
Maybe you find an S6 owner in your area in the german tvcc section ?
There are some who have good knowledge of the S6 engine, and there is at least one company having rebuilt more than one s6 engine.
Mine very rarely ran that hot, even after some very spirited driving for 2 hours in 30 degree heat.
I wouls start with the stat, maybe flush and replace coolant. Oil is water cooled in the Tusc so that seems like a common cause.
Check rad for damaged matrix etc.
Please don't use 95 ron fuel. If its running lean it will also be hotter than normal.
I wouls start with the stat, maybe flush and replace coolant. Oil is water cooled in the Tusc so that seems like a common cause.
Check rad for damaged matrix etc.
Please don't use 95 ron fuel. If its running lean it will also be hotter than normal.
blueg33 said:
Mine very rarely ran that hot, even after some very spirited driving for 2 hours in 30 degree heat.
I wouls start with the stat, maybe flush and replace coolant. Oil is water cooled in the Tusc so that seems like a common cause.
Check rad for damaged matrix etc.
Please don't use 95 ron fuel. If its running lean it will also be hotter than normal.
The fuel is clearly not the problem, nor is it for "normal" use. A blockage or a fault on one the thermostats (I assume the oil cooling is thermostatically controlled) is the most likely.I wouls start with the stat, maybe flush and replace coolant. Oil is water cooled in the Tusc so that seems like a common cause.
Check rad for damaged matrix etc.
Please don't use 95 ron fuel. If its running lean it will also be hotter than normal.
Fire ring failure on head gasket considered?
TVR_owner said:
The fuel is clearly not the problem, nor is it for "normal" use. A blockage or a fault on one the thermostats (I assume the oil cooling is thermostatically controlled) is the most likely.
Fire ring failure on head gasket considered?
The fuel may not be the problem with the temp issue, but for me, on my car and all others with a TVR Power warranty, one of the warranty conditions is that you use 95 ron or higher. Knowing Dom, he wouldnt say that for the sake of it.Fire ring failure on head gasket considered?
blueg33 said:
The fuel may not be the problem with the temp issue, but for me, on my car and all others with a TVR Power warranty, one of the warranty conditions is that you use 95 ron or higher. Knowing Dom, he wouldnt say that for the sake of it.
I guess you mean 98 and higher. If I was backing a 5 year warranty, I'd mitigate risks as far as possible too.
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