Porsche Enthusiasts Club Forum

Hi all,

I have owned my 944 for just under a year but have only just joined this forum. We bought it last March to go on a European rally last September. Whilst it was running hot in Europe it didn't overheat. Unfortunately the clutch went pop before we made it back.

We picked the car up before Christmas with the clutch replaced but when I drove it for the first time a week or so later the temperature gauge went berserk. The car was dry of all coolant and I discovered a split in the engine to heater matrix. I replaced this and tried to refill the coolant but it wouldn't take more than 3l of fluids. It started to get really warm when I tried to run the car to vent it.

I drained it at the weekend and flushed the radiator through. I replaced the thermostat (it was 87c rated and not fully open until 97c, the replacement is 80c and open by 87c). It is running cooler but still hot and the fan is not kicking in. I am thinking I need to replace the thermo fan switch but I have a stupid question - all the information I have seen say there should be two fans. My car only has one on the passenger 1/2 to2/3 of the radiator. So am I missing a fan and is that why the car is running warm please?

Also what is the easiest way to get at the switch to remove it please as it seems quite buried and difficult to reach from the top of the engine.

Sorry for the rambling first post!

My car is a 1986 2.5 oval dash by the way.

Thanks,
Stuart

Hi,

I've got the same model 944 and I've only got one fan. I think its only 3.0 litre cars and/or air con cars that have twin fans. I think you're in the right area, putting a cooler thermostat is a good idea, the problem with higher temp ones is that they don't allow open enough to let coolant through the radiator hence the thermoswitch doesn't activate the fan. You can take the wires off the thermoswitch and touch them together and this should make the fan start. If the fan does start then you can suspect the thermoswitch or not enough coolant in the radiator. It should be pointed out that bleeding these cars can be a pain. As you've changed the heater matrix I suspect that it hasn't filled up properly. Getting the front high, taking the bleed screw out and slowly filling up the reservoir until it flows out of the bleed screw, then start the car and use some revs to force air pockets out should help.

I would not profess to be an expert but here is my experience on fans and coolant bleeding.

The fan switch failed on my 86 944 Turbo. When it failed it failed "on" so fans were running continually unless the relay was removed. The turbo does have twin fans or at least an air con fitted car does. It has a different switch which I learned by buying the wrong one.

The switch is not too difficult to swap. You'll need to approach it from underneath. Jack up the front of the car and remove valance, sump guard etc so you can see the bottom of the radiator. You can then get your hand up to the switch in the radiator and remove the plug. You will need a deep socket (i think 27mm but dont quote me) which will undo the switch. If you are really fast and lucky you wont get too much coolant in your face when you remove and replace. Tighten up the new one, reconnect electrical connector. Easy! Dont put everything back until you are 100% confident that nothing is leaking. I spent a whole weekend chasing water leaks round. Fixing one exposed another somewhere else.

Replacing coolant and bleeding was a different matter. Google presented this as an option and it worked for me. Fill header tank to the correct level with the right coolant mix. Start the car and undo the bleed bolt. Let the car warm up. Increase the revs to get the water pump to do it's job and top up coolant as required. The system is very prone to airlocks and I cured mine by pulling out the overflow pipe from the tank, covering the tank filler with my hand and then blowing down the overflow. Effectively burping the system. Worked for me!

Clarks Garage has a tutorial on fan switch replacement.

If you are interested I have a brand new fan switch for a non turbo car. Genuine Porsche. You are welcome to it for a tenner including post.

Hi Andy and Martins,

Thank you both for taking the time to reply, it is really appreciated, and reassuring!

Martin, switch sounds great. Can you PM me your PayPal or bank details and I will send you funds and my address? Do you think if I transfer money you could post to arrive on Saturday?

Thanks again,

Stuart

Hi Martin,

Thermofan switch arrived today, thanks. Thanks again for sending this so quickly.

Stuart