997.1 Coolant problem

[Mariosbt]

I have a 2007 997.1 C2 Tiptronic. The car has just had all the coolant pipes (front to back) replaced & LTT fitted. On picking the car up, after 5 miles a red light flashed and read Temp. Gauge Failure. I immediately took the car back & they topped up the system with coolant.
I got the car home, the next day I checked the coolant level, it was fine. I took the car out & 6 miles down the road the same warning light flashed.

I got the car home & phoned an Indy closer to home.. took the car to him, he said it would be an airlock & booked it in. He drained & refilled (vacuum) the system…. £150 by the way.

The next day I took the car out.. 8 miles down the road, the temp. gauge failure warning came on again. I got the car home & plugged in my diagnostics tool. TBH I am not too familiar with the tool & the instruction booklet has microscopic font ffs! I will post photos below. If anyone can shed any light on the problem I would be grateful or next stop is OPC ££££££

[Discombobulate]

No idea about the code. But having been where you are: 1. air locks are v common and almost impossible to completely eliminate so be prepared to check and top up over next hundred miles. 2. My next stop would be new reservoir cap if not changed. Not expensive.

[Mariosbt]

Discombobulate said:

No idea about the code. But having been where you are: 1. air locks are v common and almost impossible to completely eliminate so be prepared to check and top up over next hundred miles. 2. My next stop would be new reservoir cap if not changed. Not expensive.

I’ve had the car almost 7 years… not a problem until they renewed these coolant pipes & fitted LTT. 2nd LTT I’ve had fitted.. had one put in 6 years ago. Coolant level not dropping. It doesn’t seem to be circulating as if a valve may not be working. Cars seems fine up to about 7 miles into journey.

[olv]

I have just changed the water pump on mine so similar work.

With the cabin heater on high (and the AC off) with the blower set to the windscreen, if you just let it idle does it get up to temp and does warm air come out after a few minutes? Does it come up to temperature when you drive it?

Also you can turn the wheels on full lock and you should be able to feel warm water in the crossover pipes in the front arches running to the radiators.

Does your ODB tool let you view live temperatures? Worth keeping an eye on that as you really don't want to overheat it and the water temp gauge is highly buffered (unlike oil).

The air bleeder valve on the coolant tank can be left in the open position and you can drive around if you want to burp air out of the system.

[Mariosbt]

Since the work, the oil temp goes up very slowly, the water temp will go up then after about 7 miles will red light warning starts flashing, needle drops to zero & indicates Temp Guage Failure on Rev Counter display. Coolant in expansion tank barely warm after 10 miles. A bit worried about driving it now. OPC only 5 miles from me, that might have to be the option if my Indy doesn’t know!

I will go & check the heater now but won’t be taking car out tonight.

Edited by Mariosbt on Tuesday 16th November 16:34

[Sublime]

Mariosbt said:

The car has just had all the coolant pipes (front to back) replaced & LTT fitted.

Have you checked that the replacement thermostat isn't faulty? To me from what you've described if the system is properly bled and you've not got an airlock I'd be suspecting that the part was DOA?

[Mariosbt]

Sublime said:

Have you checked that the replacement thermostat isn't faulty? To me from what you've described if the system is properly bled and you've not got an airlock I'd be suspecting that the part was DOA?

How would I check the LTT?

The heater is blowing warm air onto the screen.

[Sublime]

Mariosbt said:

How would I check the LTT?

You'd need to remove it and drop it in a pan of water that you bring up to boil to see if it actuates. However you'll need to drain some coolant first to do that (and then top back up). That said I'd have hoped the Indy after you took it back the first time would have tested that they'd fixed the problem when they drained and re-filled it. At which point they'd have realised it wasn't working. So next thing is they should have fitted a known working thermostat to rule that out in my opinion.

[Mariosbt]

Sublime said:

Mariosbt said:

How would I check the LTT?

You'd need to remove it and drop it in a pan of water that you bring up to boil to see if it actuates. However you'll need to drain some coolant first to do that (and then top back up). That said I'd have hoped the Indy after you took it back the first time would have tested that they'd fixed the problem when they drained and re-filled it. At which point they'd have realised it wasn't working. So next thing is they should have fitted a known working thermostat to rule that out in my opinion.

All The initial work was done 50 miles away. The Indy that drained & refilled the coolant was local. He won’t have checked the thermostat. However this is giving me stuff to build on!

[olv]

If you're getting warm air in the cabin then water is circulating to the heater matrix at least so your water pump is working. An airlock big enough to stall the whole system seems unlikely given you've just had it vacuum filled so thermostat not opening when it gets up to temp could be a cause.

Having just taken my own thermostat off as part of the water pump work I wouldn't recommend it as a casual route of diagnosis though!

[Slippydiff]

Slippydiff said:

Mariosbt said:

3.6 C2 Tiptronic S

In that case, I'd look into this :

Faulty Change Over Valve (COV) Solenoids
Symptoms: Exhaust Flap Failure or Heater Shut Off, etc.
The vacuum solenoid or change over valve has been an issue on all the 911 chassis.

The device is designed to direct engine vacuum to effect a mechanical change when requested to by an electrical control unit e.g. open a vent, change the position of an exhaust flap, redirect hot air from feet to screen etc. Likely systems effected include:

1. Air Cleaner Flap
2. Acoustic Simulator
3. Heater Shut-Off Valve
4. Exhaust Flaps
5. Coolant Shut-Off Valve on Engine Bypass Circuit
6. Tuning Flaps
7. Shut-Off Valve on Heat Exchanger for Gear Wheel Set Oil
8. Shut-Off Valve for Clutch Fluid Heat Exchanger (PDK ONLY)
9. Fuel Tank Vent Valve

Porsche has used the COV in many circumstances throughout the 911 chassis, so if you have a failure related to a mechanical device controlled by vacuum, look for a failure in the COV solenoid in the system first.

Most recently, the 991 cars have had all of their COV solenoids replaced in a maintenance campaign.

Note the comments in the last but one post on here :

https://www.renntech.org/topic/36660-coolant-shuto...

[leegrear]

Possibly a sensor issue
paste image below.


http://i849.photobucket.com/albums/ab55/infrasilve...

[Mariosbt]

The guy that did the drain & refill of the coolant system is having a look at the next opportunity. The car won’t be going out in a hurry in this sh!tty weather , so no immediate rush to sort it!

I will keep you posted on the outcome.. pretty certain this is not the first time this problem has occurred.

[Porschekiduk]

The fault showing is coolant shut off valve, this is for the gearbox coolant control, its at the back of the box, near gearbox mounts.

They fail and give same warning, as if engine temp sensor failure.

They can opened with diagnostic tester, but may have lost vacuum to the solenoid.

[olv]

How did the diagnosis go?

[Mariosbt]

olv said:

How did the diagnosis go?

I have now taken the car to OPC. It is being looked at on Thursday so should know then, car not overheating.. so coolant is circulating

I will post results when I hear.

[Mariosbt]

anonymous said:

[redacted]

That could well be it. Just had PSE removed & Topgear Sports Boxes fitted

[stevemcs]

I know these are a pain to bleed but the one thing i struggle with is the charge of £150 for a drain and bleed after they drained the coolant in the first place, I wouldn't dream of charging the customer for that.

[Mariosbt]

stevemcs said:

I know these are a pain to bleed but the one thing i struggle with is the charge of £150 for a drain and bleed after they drained the coolant in the first place, I wouldn't dream of charging the customer for that.

No, it was a different indie that drained it the 2nd time.

[stevemcs]

Mariosbt said:

No, it was a different indie that drained it the 2nd time.

Ah, that’s ok then,