Manual fan control

[steves944]

My 944 has a recurring problem with its cooling system.

This last couple of weeks, cos of the cold weather, in normal driving the temp gauge sits firmly on the first line on the gauge and i get good heat through the vents. Soon as I come into traffic the gauge rises rapidly but the fan doesnt come on and I either have to turn off or pray for a gap in the traffic! I have put a new relay in 2 weeks ago.

Today I went to London and back - about 160 miles and soon as I hit the M25 queues the gauge went up but I was prepared with a 5 litre can of water and pulled off to watch from the engine bay. The top hose and lower hose from the rad dont seem too hot yet the gauge is near the top. In fact there didnt seem much water in those hoses as I could squeeze them up easily!.

I carefully took off the expansion tank cap and the water started to overflow after a couple of minutes so I turned off and refilled.

Driving home I noticed a faint smell of coolant fluid but water level is good and no overheating.

I've also noticed the exhaust seems to have a lot of vapour in it yet there is no sign of water in oil or vice versa.

2 things - a) does this sound like a problem coming up and b) should I wire up the fan manually anyway?

Thanks

 

[Riverside]

a) turn the heater to full heat, full fan to keep the car from overheating. I drove (90 miles) back from Silverstone with a stuck thermostat last summer like this.

b) if you have aircon the fans come on at slow speed when you press the aircon switch (whether the aircon still works or not).

c) if you don't have aircon the thermostatic switch in the rad only has two wires so wiring up a switch would be a piece of cake.

d) the thermostatic switch is about £6 & easily a DIY job to change as long as you have the right (big) socket & can refill & bleed the coolant after you've finished.

 

[steves944]

Do I need to do something special to bleed the coolant system

 

[robwright]

Nothing too special mate I have just redone mine again. Handy guide for it and everything else here:

www.clarks-garage.com

Go to garage shop manual and cooling system draining, filling and venting.

Good site this one mate. Saved my bacon no end of times.

 

[Mike_Pollock]

Bleed valve is on the top of the elbow on the front of the engine, think its 12 mm.
They are amazingly difficult to bleed, minimum 3 or 4 attempts.
If the hoses are empty then maybe the thermostat isn't allowing water to flow. It's mounted in the block at the top of the bottom hose.
Also check the coolant cap, I had several niggles cured with a £5 cap!
Mike

 

[robwright]

It is 12mm you will need a 1/4" drive with a 100mm extention to undo it. If you follow clark's instructions about raising the front of the car. The bleed screw must be the highest point in the system. Ie elevated above the heater matrix then it should be simple. Do it once cold then open up the screw to do it again once the engine is at temp and all should be well. Mike is prob spot on with the thermostat though. If it is not letting water to flow to the rad then the fans will never come on. I have the opposite on mine. The thermostat lets water to the rad almost immediately meaning that in this weather the car takes a very long time to get up to temp. Not sure if it is possible but you might be able to eleviate your overheating by removing the thermostat altoghether for now. Again I am not sure if that is possible just a theory.