Failure indicator. Oil temp & coolant temp drop to zero

[mindthegap]

Hi. I have intermittent failure indicator message on dash with oil & coolant temp drop to zero whilst driving. Does return to normal during driving but then problem re-occurs. I have had oil level sensor changed but problem remains. Seems to me to be electrical but don't know what to check / change next. Any advice gratefully received.

 

[deMort]

Is the car a Tiptronic ?

If so the grey electric valve ( vacuum ) on the gearbox has possibly failed .

 

[mindthegap]

Yes it''s tiptronic

Ok thanks for the advice. Is that a big job / expensive part can you tell me please?

 

[deMort]

No and No .. remove the rear undertray .. look upwards at the box on the n/s and to the rear of the box .. there is a grey valve next to a diaphragm with a rod on it .. car off and it will be in the down position , car running and when starting from cold the rod will move upwards .

If it does this then it's all working fine and the fault is nothing to do with this system .

If it doesn't then the grey valve is the usual cause .

 

[mindthegap]

Items replaced but still have problem

Hi. All of these items now replaced but problem comes back. Replaced:

Coolant Hoses requiring removal of engine & transmission.
Gearbox Cooler bypass valve
Thermostat
Temp sensor
Radiator cap
Oil level & temp sensor combined
Breather hose

I understand there is another sensor in the expansion tank that detects the level so it might be worth changing that as it sounds like its throwing up at level error rather than temp error?

Or anything else to look at please. Any further advise is appreciated

 

[deMort]

There is a level sensor in the bottom of the coolant tank.

Can i just confirm that with the gearbox valve you have looked at the position of it engine off and cold .. then started the car and looked to see that it has Actually moved to the up position ?

If it moves then this system is working fine .. if it doesn't then this is an issue .

The electric valve is the usual but it might also have lost vacuum to it as well .

 

[askgeez]

Perhaps because car isn't getting as much use due to lockdown. I have exactly the same issue. It did this once before, last year, after being left. I cleared CEL and it didn't happen again for months .

Annoying that it occurred just a couple of weeks after being into the OPC for full service.

In addition to oil and water gauges , mine decided to throw an amber CEL recently, then sensors went to 'normal '.... I think it's sulking :grin:

Because It happened 2nd week December , I've not driven car at all , for fear of it being anything more serious.

It's a manual GT3.

 

[deMort]

From memory the GT3 has the same cooler and valve as the Tiptronic boxes ..

As such the grey electric valve is the first thing to check.

The symptoms are usually you start with no issue .. the coolant temp stays low ( 40-60 ) whilst the oil gets hot as you drive ..

Sooner or later the car realises the oil temp is far above what the coolant should be and drops the gauge to zero followed by a warning light ..

Thats to tell you the coolant gauge is inaccurate .

The test i listed is the quickest way to prove its functioning .. see if the vacuum valve raises when the car is started from cold .

 

[graham.hassall]

Are you sure you have vacuum on the gearbox coolant valve?
Check out this post which I made a long time ago.

http://911uk.com/viewtopic.php?t=79586&highlight=

The problem I had was no vacuum due to broken connection on the vacuum reservoir.
Good luck
Graham

 

[graham.hassall]

To prove to myself that this was the problem. I manually closed the valve and bound it with wire. I then took the car for a short drive and all was good. I then had to trace the problem which in my case was the lack of vacuum

 

[mindthegap]

replacement change over solenoid valve has fixed the problem

Thanks for all the advice. It seems that the gearbox vacuum solenoid valve was only working intermittently. This is now replaced (£40 from Porsche) and problem seems permanently fixed.

 

[Edinburger]

From memory the GT3 has the same cooler and valve as the Tiptronic boxes ..

As such the grey electric valve is the first thing to check.

The symptoms are usually you start with no issue .. the coolant temp stays low ( 40-60 ) whilst the oil gets hot as you drive ..

Sooner or later the car realises the oil temp is far above what the coolant should be and drops the gauge to zero followed by a warning light ..

Thats to tell you the coolant gauge is inaccurate .

The test i listed is the quickest way to prove its functioning .. see if the vacuum valve raises when the car is started from cold .

I have the exact same intermiting problem on my 997.1 Turbo, do you know if this has the same valve?