Engine over heating when accelerating
Discussion
I have a Porsche with a 4.8L engine. I had issues with overheating when stationary so had some parts changed. I think it was water pump and thermostat. That solved the stationary issues.
However, if I drive for an hour in normal traffic with speeds up to 80 mph (not UK) I’m fine. If I tap the accelerator pedal and drop a gear for anything over 10 seconds the water temp shoots up and then the oil starts to climb. If I lift off and coast for a minute the oil and water temp go back to normal almost as quick.
I know the water temp pings max when it is low in a Porsche. That is what drew my attention on the first issue. But, I checked the level and it’s fine. I can also smell that warm smell of an engine for a second when it happens so I think it’s real.
I have only seen this happen twice in 6 months. After the first time I took it to a trusted independent and he couldn’t find anything. I then took the car out and drove it to provoke the issue and nothing.
The water temp goes from normal to near max so quick that you wouldn’t believe it to be real. 10 seconds and it is near max coast for 10-20 more seconds and it’s back to normal. I know the Porsche temp is fake and only changes the reading when things go out of spec. That would account for the quick rise. But, as soon as it goes up I let off the accelerator and it stops going up and quickly returns to normal.
Is it possible it’s just a stuck thermostat or water pump? Am I missing something?
However, if I drive for an hour in normal traffic with speeds up to 80 mph (not UK) I’m fine. If I tap the accelerator pedal and drop a gear for anything over 10 seconds the water temp shoots up and then the oil starts to climb. If I lift off and coast for a minute the oil and water temp go back to normal almost as quick.
I know the water temp pings max when it is low in a Porsche. That is what drew my attention on the first issue. But, I checked the level and it’s fine. I can also smell that warm smell of an engine for a second when it happens so I think it’s real.
I have only seen this happen twice in 6 months. After the first time I took it to a trusted independent and he couldn’t find anything. I then took the car out and drove it to provoke the issue and nothing.
The water temp goes from normal to near max so quick that you wouldn’t believe it to be real. 10 seconds and it is near max coast for 10-20 more seconds and it’s back to normal. I know the Porsche temp is fake and only changes the reading when things go out of spec. That would account for the quick rise. But, as soon as it goes up I let off the accelerator and it stops going up and quickly returns to normal.
Is it possible it’s just a stuck thermostat or water pump? Am I missing something?
Thank you for the relies.
The parts were from Porsche but the cooling on these engines is known issue with parts failing.
I had read about the radiator being possibly the issue so that might be the next point to address.
To the wiring point, the way the temp rockets up would make me think low coolant as that’s what Porsche do when the level is low. But, the oil temp goes up as well. Not to worrying levels because I know to back off and everything goes back to normal. The only thing is that the first time it happened I only looked because I smelt a smell of warm engine as if the heater had just kicked in. The same thing happened today.
The final piece that is odd is that it happened on the same long drive I took 6 months ago. Not at the same point but it’s as if it takes several hours for the issue to arise. When I tried to recreate it locally, I had the car well up to temp and I drove it like I had never driven before. Nothing happened.
I wonder if my driving style has added in some way to the issue. I have never driven over 3k revs while the car isn’t up to temp.
The parts were from Porsche but the cooling on these engines is known issue with parts failing.
I had read about the radiator being possibly the issue so that might be the next point to address.
To the wiring point, the way the temp rockets up would make me think low coolant as that’s what Porsche do when the level is low. But, the oil temp goes up as well. Not to worrying levels because I know to back off and everything goes back to normal. The only thing is that the first time it happened I only looked because I smelt a smell of warm engine as if the heater had just kicked in. The same thing happened today.
The final piece that is odd is that it happened on the same long drive I took 6 months ago. Not at the same point but it’s as if it takes several hours for the issue to arise. When I tried to recreate it locally, I had the car well up to temp and I drove it like I had never driven before. Nothing happened.
I wonder if my driving style has added in some way to the issue. I have never driven over 3k revs while the car isn’t up to temp.
Edited by h0b0 on Monday 20th March 23:59
On another thread it was suggested that my thermostat could be at fault. I was under the impression a thermostat was on or off as has been posted in this thread. However, the poster on another forum suggested the thermostat is variable and can be overridden by the sport button.
It sounds feasible and now I have checked my invoice I see the housing was replaced and not the thermostat.
Edited to add the thermostat part was not listed but it was in the labor so I assume the thermostat came with the housing.
It sounds feasible and now I have checked my invoice I see the housing was replaced and not the thermostat.
Edited to add the thermostat part was not listed but it was in the labor so I assume the thermostat came with the housing.
Edited by h0b0 on Saturday 25th March 00:57
I took a look and see I failed post my mid week update. I must have been distracted and not hit post.
I’ve been away all week with work so have not had chance to do much diagnostic work. I drove back last night and saw it happen again.
What I did check while at the hotel was coolant level, at max, and oil level at an acceptable level but had room to top up so I did once home. Porsches use oil. It’s odd but they do. I checked for oil color and it was good so no head gasket issues.
I also researched a lot because of the failure being quite distinctive and not making sense. A Porsche mechanic said it was typical of a failed thermostat. Initially, I was still confused as I had not heard of the concept of an electric thermostat and the mechanic hadn’t made that part clear. That’s why I came back here.
It now makes some sense. I checked the invoice from 6 months ago and while the thermostat isn’t listed, the housing is and in the details they said they replaced it. The issue started after the replacement.
The conclusion then is to change it under the two year warranty from Porsche. I just hope the mechanic also has a warranty because it was $900 labor last time to replace a working part with a broken one. Having said that, I know it would be crazy not to change it once the work has been done to replace the housing.
Footnote, the oil temp on a Porsche appears to react with temp change. The water temp doesn’t react until there is a potential problem and then shoots up. It doesn’t give an accurate display of temperature and is just a way of providing a warning.
I’ve been away all week with work so have not had chance to do much diagnostic work. I drove back last night and saw it happen again.
What I did check while at the hotel was coolant level, at max, and oil level at an acceptable level but had room to top up so I did once home. Porsches use oil. It’s odd but they do. I checked for oil color and it was good so no head gasket issues.
I also researched a lot because of the failure being quite distinctive and not making sense. A Porsche mechanic said it was typical of a failed thermostat. Initially, I was still confused as I had not heard of the concept of an electric thermostat and the mechanic hadn’t made that part clear. That’s why I came back here.
It now makes some sense. I checked the invoice from 6 months ago and while the thermostat isn’t listed, the housing is and in the details they said they replaced it. The issue started after the replacement.
The conclusion then is to change it under the two year warranty from Porsche. I just hope the mechanic also has a warranty because it was $900 labor last time to replace a working part with a broken one. Having said that, I know it would be crazy not to change it once the work has been done to replace the housing.
Footnote, the oil temp on a Porsche appears to react with temp change. The water temp doesn’t react until there is a potential problem and then shoots up. It doesn’t give an accurate display of temperature and is just a way of providing a warning.
stevieturbo said:
And again, without doing some proper testing and viewing live data, changing parts at random is pissing in the wind, warranty or not.
As stated in the OP, I am not in the UK. It is 9AM here. What time do you suggest I get up to start work on it? "Kids, make your own breakfast I have to go out and recreate something that happens once every 3 months. I will be back in June. Please do not burn the house down."
I think a little research while I can't work on the car is useful. I am not part cannoning it.... I have accurately diagnosed the issue. My research led me to people who knew what they were talking about.
I have tried to remain civil as I am grateful to those responding but your attitude sucks and your contribution is worthless. As stated in my OP, the oil temp tracks with the water temp. The two independent temperatures may not be accurate, but they show the temp is increasing and that is the problem that needs to be fixed. Those that know about the 4.8 V8 engine (stated in my OP) knew immediately what the issue was.
stevieturbo said:
So have you checked actual temperature like I said ?
Or just done nothing useful ?
Or just done nothing useful ?
stevieturbo said:
And again, without doing some proper testing and viewing live data, changing parts at random is pissing in the wind, warranty or not.
stevieturbo said:
It is odd people get so offended when told the truth, and are given info on how to diagnose problems. OE gauges are worthless for such problems.
These are all simple facts.
If you know what the issue is then, congratulations, all is fixed.
I’m not offended in the slightest. But, I think it’s important in life when someone is speaking to you like sThese are all simple facts.
If you know what the issue is then, congratulations, all is fixed.
t to call them out on their bull st. Surely…surely…. If I have a f
king warranty I should go back to the fking garage with the warranty? One of us diagnosed the problem. The other is you.
Bringing some closure to this. Both the original mechanic and Porsche were initially unable to diagnose the issue and were reluctant to throw parts at it. But, through a process of elimination through testing, it could only be the thermostat so we had it changed and resolved the issues.
What came to light was the original mechanic did not replace the thermostat, only refitted. That is madness considering the work done to get to it.
I had told the dealer I was going to sell the car. When I went to pick it up they had it on display up front and had lined up people to see it. No offers made due to it not having the tow package though.
What came to light was the original mechanic did not replace the thermostat, only refitted. That is madness considering the work done to get to it.
I had told the dealer I was going to sell the car. When I went to pick it up they had it on display up front and had lined up people to see it. No offers made due to it not having the tow package though.
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