nedkelly

Hello to all on this forum. I have just posted this on 968.net and got some goo replies so I was hoping there are some more out there who would like to add their 10 cents worth:

I have just purchased a 1992 968 Tip Coupe. Only had it a couple of days but just drove to work and switched it off but the electric fan carried on running. No problem I thought, must be a thermal switch or something keeping the fan on for 5 or 10 minutes I thought. Well 1 and a half hours later the bloody thing is still going round! Good job I checked or I feel my battery would be dead right now. As I don't have any manuals right now and can't get back to the dealer until the weekend I have resorted to pulling out the big relay (G10) from the fusebox. Anybody had this problem before and got any advice?

Any pointers would be welcomed as I can't resort to to lifting the bonnet (excuse me I meant hood!) every time I drive the darn thing to remove the relay.

RajDatta

The relay is what controls the fan. See if you have another member closeby who can lend his relay and this way you can eliminate it.
Usually when the fan switch lets go, it lets go in full power position.
Do you still have ability to switch speeds on the fan?

wjk_glynn

As mentioned by 968TurboS, the radiator temperature switch can fail. A quick way to test is to unplug the cable which connects to this switch. If you unplug this cable and the fans stop, then you know its the switch (or less likely some weird problem in the cable but that very unusual). If the fans don't stop, the problem is else where.

To see this switch, face the radiator and look down on the righthand side on the raditor side facing the engine. You should see a cable plugged into a sensor (i.e. the radiator temperature switch). Simply unplug.

WARNING - Your fingers will be in very close proximity to the fan blades so I'd either remove the relay or disconnect the battery during the unplug/plug step. Also, make sure that when the cable is hanging free, make sure it doesn't snag on the fan blades.

Karl.

nedkelly

Thanks guys for the input. The relay I believe is okay as I had it on the bench and removed the can to test it and all the 4 contacts inside are nice and clean with no 'pitting' at all. I too suspect the thermal switch on the radiator but i need someone with hands the size of 'small handed thing'! All Porsche mechanics must have their hands bound as children so as to fit into these tiny spaces.

If you remove either of the fuses 'cooling fan 1' or 'cooling fan 2' then the remaining fan goes into 'lightspeed' mode which I am guessing is a safety feature for fan redundancy. I could remove both fuses but it's easier to unplug the relay as it's in the fuse box anyway.

Thanks again Karl/968 TurboS

RajDatta

Ned, taking the fan shroud is not that bad. It will require lifting your car on jacks and removing underpinning. Once everything is out of the way, you can remove shroud by removing six 10mm bolts and disconnecting the fan wires. At that point, you can slide the shroud from the bottom.
Have a new thermo switch handy and swap them. You will lose some coolant so be ready to bleed the system and topping it.
Its very simple, go for it.

nedkelly

968 turbo
I read on one of the forums there were tricks involved in refilling thr cooling system and bleeding. No further info though. You will have to forgive my 'freshness' here as this is my first Porsche so I am now only just researching the model. One of the U.K guys is sending me a maintenance manual on CD so that should be a great help also.

RajDatta

Ned, its pretty simple, top the coolant expansion tank, run the car for sometime. Turn your heater to max. Open the bleeder screw which is on your coolant neck when facing the top of the engine. Bleed it until you see coolant spewing out, close it. Shut the car off, wait for it to cool off and top off fluid in coolant tank.

nedkelly

968 turbo,

That's cool thanks (pun intended)

RajDatta

You got it! lol

sayporsha

In my experience bleeding my 968 and 951, I have found that it requires several bleedings to get all the air out. It can be accomplished in 1 warmup cycle, though. Small bubbles throughout the cooling system slowly make their way to the highest point on the engine: the cylinder head. They accumulate there, forming an air pocket. The air pocket must be bled occasionally during warmup to prevent it from getting too large. Coolant must be added during the process to displace the air. Here's the process:

Open the valve while refilling the cooling system. Close the valve when what comes out of it is more coolant than bubbles. Start the car with the reservoir cap off. Every few minutes, open the valve to let the air out. Close it when clear coolant runs out. Top off the reservoir to keep the level up. Repeat this process until no more air comes out. If you raise the engine speed it makes foam in the air pocket. Be sure any foam settles before the final bleed. The air is usually gone by the time the radiator fan comes on. Now you're good to go.

Next time the car is stone cold, top off the reservoir one last time because the coolant level drops slightly after cooling.