Racerron

Hi Viken,

Do you have a copy of the vacuum hose schematic for the contol valve and solenoid that controls the coolant flow through the transmission oil cooler?

The reason I ask is that just prior to putting the car away I had a recurring CEL code p0118 I think relating to the CTS.

The local dealer looked at the problem but could not find it althugh the Porsche tech line sort of pointed them to the valve for the trans. cooler.

I just checked today by removing the belly pan and was amazed to find that there is no vacuum hoses at all going to the control solenoid of the valve. The PET shows a hose connecting the valve to the solenoid and another vacuum hose going off into nowhere. There is a 4-way vacuum "T" at the L/F of the motor with one of the ports blocked off with a little alloy plug. I would think that this would be the vacuum source. I have nothing in the workshop manuals as they only go up to 2003.

If any one else is reading this and they are able to get their car up in the air I would appreciate knowing if I am the only one with missing vacuum lines or if all the GT3's are like this.

It makes no sense to me that the factory would install a valve and control solenoid just to leave it open. The default position is open allowing full flow of coolant from the engine to the rads, bypassing the thermostat.

The valve looks like a 928 or 85/2 944 heater control valve.

The valve and solenoid are located just forward of the trans cooler located on the L/H side (drivers) of the transmission.

mds

Ron, I'm really not sure what I'm looking at here, but here are some pictures of my car.

The first picture shows the rear side of the cooler with one hose running to a tee, one side of which going toward the front of the car and the other side toward the rear. The black gizmo looks like a sensor with wires running under the transmission across to the other side of the car and then up into the car.

The second picture shows the front side with two hoses, one steel braid going directly to the transmission casing, the other running forward. It looks like a vacuum line runs from the black valve to a solenoid and then toward the rear of the car and disappears on top of the transmission. Wires from the solenoid join up with the sensor wiring mentioned above.

mds

Ron, the vacuum reservoir on my car also has one port plugged. But it looks like another port leads through a check valve to a manifold of some sort with multiple lines running off in various directions. Its hard to see because the plumbing runs forward alongside the engine. The 2004 PET shows this assembly, but it doesn't show clearly where these lines run to. My guess is that one of them does connect to the line I see on the cooling solenoid. So I agree, it does look like something is missing on your car.

Racerron

Thanks Mike, Yes the whole #&^%$**!@ing vacuum hose circuit for that valve in the 2nd pic is missing on my car.

How could this be...maybe too much beer for lunch!

mds

Ron, in answer to your PM, here are a couple more pics.

The first shows part of the cooling vacuum line that runs from the second port of the cooling solenoid back toward the rear of the car. It disappears on top of the transmission. I can't figure out how to get access to see where it goes. The part you can see here is clipped to the side of the transmission case. It is a fairly thin line, thinner that the line that connects the solenoid to the cooling line valve in my previous picture.

Edit: Delete second pic.

Maybe your dealer can check with their PCNA service rep and get info on where this line goes and what you need to do to gain access.

Racerron

Many thanks for the extra pics Mike. Although I think that your vacuum reservoir is actually the fuel filterand the plugged port is the fuel pressure test connector.

I've got the dealer scratching his head with the first pics at the moment.

Thanks for all your help!

mds

Oops.

Racerron

An update to this post is that neither of the dealers in my area have been able to discover anything about the missing lines and one even suggested that "Well, maybe your car doesn't need them"
Anyway I took matters into my own hands and fabricated the hoses from some hard vacuum lines I had and a couple of 928 rubber elbows. I installed my own hoses as I thought they should be installed and lo and behold the problem is cured.

I now have heat and the CEL doesn't come on anymore

Thanks to MDS for his help, and a big brickbat to both the local dealers.

Phokaioglaukos

Rennlisters 1; Dealers 0

Very hard to believe, though, for this issue.

Racerron

Yes PK strange but true, I would still be resetting the CEL every time I drove the car if I hadn't taken the time to research the problem myself.

What was happening is that the water valve for the trans cooler is open in the default (no vacuum) position. So as soon as the engine started, coolant was being fed to the R/F radiator and was bypassing the engine thermostat. Because of this the engine never reached full operating temp. It was as if there was no thermostat at all. Wanna buy a good new thermostat and gasket?
What is supposed to happen is that the water valve is closed until the trans temp sensor (when trans temp reaches the point it needs cooling) signals the change over valve (vacuum solenoid) to switch off the vacuum and allow the water valve to open thereby opening the coolant loop for the trans cooler.

Clear as mud? It's not complicated really, but I just make it seem like that with my superb command of the English language

Phokaioglaukos

Votre anglais est tres bon, je pense que je comprends tout cela. Appellez-moi Chris.