Thermosat Sticking?

[s2rjn]

thanks Richard, I've just been onto the OPC and have booked it for next week, may as well with a warranty

 

[puentee]

My friend.

I have the same problem you have, only worse.

My 991 has 6,000 miles and I have changed the thermostat 3 TIMES.

The simptoms were exactly what you describe in your post. The problem is fixed for a while and then it just fails again. The 3 thermostats were bought at the Porsche dealer, so they should work.

As of now, I am trying to figure out if the problem is related to something else... the funny thing is that the problem disapears every time I change the thermostat. All the coolant levels are OK, so I am wondering if the problem could be something else, but have not found any answers or sugestions...

 

[belindarichardson]

Hi,

Got a 2018 991 4S - had a bizarre situation yesterday. been driving to Kent coast in Sport mode - stopped a couple of times en-route. At destination stopped for about half an hour and drive to another car park. Suddenly really loud fan noise from the front end, warning on dash to pull up and switch off as engine overheating. So I did. Left it 10 minutes to move car to better position same warning. AA came out about 45 minutes later as had to drive back to London - switched engine on, ran it for about 20 minutes. all perfectly fine. put into Sport and revved all fine. Drive home no problems. But taking it into PCEL tomorrow fir them to check out the water pumps. And if there is a fault will get them to replace them as it is still under warranty.

has anyone else had this issue and did you have pumps replaced?

I had a serious cooling problem with my last 2S, which started just about a year ago. Periodically the temperature gauge would shoot up to maximum, the fan would be going like crazy, and I would get a warning to stop driving to avoid engine damage. Between July and November, it went back to Porsche 4 or 5 times to be fixed, whereupon I lost patience and told them to keep the car. Good news is that they ended up doing a deal with me which resulted in me getting my lovely new GTS in March this year (I had the use of a newish Boxster while I was waiting). Anyway, on picking up the GTS, I asked what had happened to my previous car and they told me it turned out to have been a water pump issue and it was now a recognised fault. So, although your problem seems the opposite of mine, I do think you should get in touch with your dealer and have them check it out. Could be related I suppose? Good luck

Cheers

 

[JeffreyGarrett]

I had the same issue as you describe on my 2017 Targa. The water pump and 'sensors' were replaced in December of 2021. I was informed that leaking coolant from the water pump had corroded the 'sensor(s)', which I understand to work on a vacuum. This caused the same intermittent fault as you describe. I admit to not being well versed with the mechanical aspects of the system, though I was informed it is complicated and operates in a different manner, according to the driving mode selected. In my case the engine was not overheating, the coolant system was full, not leaking or showing any signs of having done so. I checked the aforementioned when the engine had cooled. When the fault report cleared the temperature returned to normal running temp straight away. The fault appeared to clear when I selected either Normal or Sport modes. I also adjusted the heating system to Max/Min.. though to be honest I have no idea if any of these actions were instrumental in return to normal operating temperature. Fortunately, I was always near to home when it occurred. It always came about after an initial run and then a restart to continue the journey, say after re-fuelling. Happy to report that since my dealership changed the water pump and the 'sensor' block, it has cured the problem. I hope this helps you remedy the problem and wish you well.

Best regards,

J.

As an addendum to my post above.... when the temperature hit the roof and the fans went into hyper-cooling mode, even though the temperature of the cooling system appeared normal upon inspection, the heater ceased to blow hot air. I didn't notice this originally as it was Summertime and the heating was off. It wasn't until December and cold, that I did notice it. I only mention this as there appears to some correlation between faulty vacuum sensors and temperature handling in general. Additionally, the engine monitoring didn't show signs of anything untoward. I originally thought perhaps I had an air lock in the heating system... but it was an internal leak from the water pump which caused the vacuum sensors to malfunction due to oxidation build up.

J

 

[rgbower]

just catching up on this thread - very useful

My car is in the dealers to fix a water pump leak. Its leaking from one of the mounting bolts - apparently there's a modification to the bracket since this is a known problem.

It would be good to advertise this as it only leaks when the system is under pressure - so there's no puddle under the car in the garage.

In my case the catch is that the system gave no warning about the loss of coolant, until the red "stop driving" light came on (and I had to be recovered by the AA - very annoying). Has anyone else had issues with "no-show" warning lights? The dealer seems at a loss to explain it.

Could it be that the the "amber warning" and the "red - stop!" signals come from different sensors??

Main point of the post --- stop reading this: go in the garage and manually check the coolant level right now!

 

[puentee]

I am replying to this same issue after trying to solve the same problem.

Reaching the 90° operating temperature takes almost 25 minutes.

Once reaching it, it will go down if I go fast, since cold air hits the radiators, going down to 80, 70, etc.

I have changed the thermostat twice, as it gets stuck oppened. I thought that the problem was a faulty thermostat, but now the third one has suffered the same problem...

I took the car to the Porsche shop and they made a diagnosis, saying that the problem is a faulty vacum cooling valve.

I AM NOT REALY SURE THAT THIS IS THE CAUSE THOUGH...

By the way, there is no message of a problem in the computer, even though the car does not get the correct temperature.

Real nightmare!

ANY THOUGHTS?

 

[mullinsm]

I am replying to this same issue after trying to solve the same problem.

Reaching the 90° operating temperature takes almost 25 minutes.

Once reaching it, it will go down if I go fast, since cold air hits the radiators, going down to 80, 70, etc.

I have changed the thermostat twice, as it gets stuck oppened. I thought that the problem was a faulty thermostat, but now the third one has suffered the same problem...

I took the car to the Porsche shop and they made a diagnosis, saying that the problem is a faulty vacum cooling valve.

I AM NOT REALY SURE THAT THIS IS THE CAUSE THOUGH...

By the way, there is no message of a problem in the computer, even though the car does not get the correct temperature.

Real nightmare!

ANY THOUGHTS?

I came to the conclusion that it was a vacuum valve problem, even though the OPC said it was all working perfectly, because the computer couldn’t find any problems. I chose to ignore it until my car developed another, unrelated problem whereby it intermittently pumped 1/2 litre of oil through the turbos when driven ’quickly’. Very spectacular, but also rather alarming when it happened. Not wishing to go through the process of being told there was nothing wrong with the car because the computer said so, I sold the car back to the OPC. I find there’s a lot less to go wrong with a Cayman.

 

[puentee]

Thanks! this is very helpful.

I will replace the valve that creates the vacum to see if this solves the problem.

This week, I will test the 2 replaced thermostats in a laboratory to see if they work. The reason is that if the current thermostat is also broken the problem will remain even if I change the valve...

 

[rgbower]

just catching up on this thread - very useful

My car is in the dealers to fix a water pump leak. Its leaking from one of the mounting bolts - apparently there's a modification to the bracket since this is a known problem.

It would be good to advertise this as it only leaks when the system is under pressure - so there's no puddle under the car in the garage.

In my case the catch is that the system gave no warning about the loss of coolant, until the red "stop driving" light came on (and I had to be recovered by the AA - very annoying). Has anyone else had issues with "no-show" warning lights? The dealer seems at a loss to explain it.

Could it be that the the "amber warning" and the "red - stop!" signals come from different sensors??

Main point of the post --- stop reading this: go in the garage and manually check the coolant level right now!

update on this … the dealer found a leak where the outlet pipe bolts to the pump… however it only shows up when the engine is hot. The solution has been to replace the pipe with a redesigned it (not to just clamp it more securely). apparently this is a very common problem!