Hi everyone, I need some advice/guidance. I think my thermostat is going, but some of the symptoms seem a little strange and not in line with a bad thermostat.

Last week on my way home I looked at my gauges and both oil and coolant temps were below 150. This was after I was in the car for about 30 minutes. What drew my attention was the start/stop deactivated. I pulled over, allowed the temps to slowly build, and got home. After the temps built, they didn’t drop it spike and the issue didn’t come back until yesterday. I did the same process and got home. Up to this point I thought it was the thermostat.

But this morning, went to start the car, and it didn’t cold start, rather it started like the car was warm. Temps were about 40, and there was no reason for the car to not have a cold start since it was sitting overnight. I drove a couple miles down the road, let a little heat, build then pulled over to allow warmup to operating temps. This seems to happen on warmer days, colder days the temps are normal and do not fluctuate.

The temps now spike a little so it looks more like a thermostat, but is running cold and not having a cold start cycle normal for a bad thermostat? The car through a code this morning for “manufacturer control” is that normal??



Any help would be greatly appreciated,

 

It's difficult to say, could be the thermostat or it could be temperature sensors(or both). When the temperature spikes, does it seem like the radiator sizzles or gets hotter than usual? If not, my guess is that your temperature sensors is giving out false readings...especially since you observed an unusual "warm" start behavior first thing in the morning. Then again, I'm not quite sure how complex Porsche thermostats are and if they are electronically controlled.

Another thing to check is your coolant level, any coolant leaks? Was it recently worked on? Air bubbles in the coolant system?

Good luck. Let me know how it goes, interested to know what you find.

 

Ask yourself what was done to car before you started seeing this behavior? Any service that involved antifreeze? Asking that because to fill car with coolant, you need a vacuum to do this, otherwise you will have air in the lines, which can cause thermostat to not function right (like running very cold even after long drives).

 

Unfortunately it just started happening. The last service was strictly an oil change 2700 miles ago. Maybe I’ll try swapping the temp sensor first like first post, then take it from there?

 

Just what temperature is your digital gauge "reading" when you say it is cold? There is a code P2181 for cold motor, a motor that runs below 140F for an unspecified period..

 

last night, before I pulled over, it was running between 147-160, and the oil temps were in the 130s. When I stopped they’d both begin to creep up, then drop down when I started moving.

 

Sounds like your thermostat is stuck open.
air flow through the radiators as you are moving is overcooling the system and the thermostat isn’t closing to restrict the flow.
if you have something like an Icarscan you will be able to read the actual temperatures which might help diagnose further.

 

Based on some other info on this forum, it seems like the sensor sits in the housing, and it doesn't seem that you can replace just the sensor. I don't think it is the thermostat, as the car will not overheat. When I get the car to temp and accelerate it, the cars temp will raise but then adjust, which makes me think the sensor is sending out a bad signal.

Can you replace just the sensor? or does it have to be the housing? and if you have to replace the housing, I am assuming it would be silly not to replace the thermostat?

 

Check out the sensors, senders and valves and their locations.
Check out if #3, the temp sensor may be the culprit (if it does not report engine temp right, I am sure when you drive, the engine gets to proper temp, just the nature of the beast).
#12 is also a suspect - the coolant temp sensor.

It is possible your oil and coolant sensors are both on the fritz, at same time. Could be both need replacing. Throwing stuff out (at work so no time to think much), but IMO these are your choices.
Let me know what you think.

 

THANK YOU!!!! I think they are both on the fritz simultaneously, this is perfect! I will report back with what I find.

 

I ordered #3 to start, waiting on it to come in, but in the meantime this is what the car now does,

When it gets up to operating temps, normal driving the car is fine. Once I get on it, coolant temp will spike (oil temp will increase), then the thermostat kicks in and back to normal temps. After it gets back to normal temps if i get on it again sometimes it will spike again other times it doesn't. I am thinking it's #12, is that the sensor in the thermostat housing?

 

IMHO You really need something like Icarscan or durametric - throwing parts at it is going to get expensive.
you’ll be able to read the actual values from each sensor.

 

Hey all, after dealing with a few more months finally took it into my indy. Suprisingly it was the thermostat, and no

 

Hey all, after a few months of dealing with the issue, finally took the car in to my mechanic. Surprisingly it was only the thermostat, and not the housing or any other related sensors. I was surprised since sometimes the car would sometimes start with a hot cycle when cold, not get to regular operating temps (staying around 125-150), other times get to temp (provided normal driving), and other times run hot and adjust constantly. These are not complaints, my wallet was very happy LoL

 

Glad to read it was a relatively cheap fix! Enjoy driving it again.