Topping up coolant - and bleeding tips..

[craiginuk]

Hi all,

Am replacing the thermofan switch so need to drain some coolant (about 2litres I think) from the radiator. What antifreeze should I be topping up with. I heard the 944 needs something special due to alluminium etc.

Also, is there anything I need to watch out for with bleeding? Front of car is on axle stands so I was planning to crack open top air bleed screw and fill till coolant come out of bleed bolt. Do I need to run the car in this position too? (not draining the block)

Thanks in advance

Craig

 

[Mike_Pollock]

Depends on the antifreeze thats already in the engine
3 main colours blue green and pink. 1 is not for ali engines cant remember which one, and colours shouldn't be mixed,

Top up coolant tank until you have water at the bleed screw, close it whilst running but open slightly several times to get rid of trapped air

 

[bmnelsc]

I wouldn't run the car on jack stands as you are actually putting the top of the rad and the coolant tank above the bleed screw. Porsche put the bleed screw on the top rad hose housing rather than the radiator or the coolant tank cause that is where the air pockets get trapped. Do put it back down to run it and as Mike says - run it up to full operating temp cracking the bleed screw at intervals as you go until you get no air and a steady stream of coolant out of the screw.

I actually checked mine a couple of times after driving just to make sure it was fully up to temp.

 

[Mike_Pollock]

I actually put the car on ramps to try and empty the head of air - the rad is the easy bit, or should be but my vapour inlet pipe from the rad to the header tank was blocked which gave me lots of fun 'till I found it.

I know some garages lift the left front wheel to help bleed them.

 

[craiginuk]

Thanks all - job done. Temp seems to sit a little higher on the gauge so not 100% sure it's bled ok. Should the flow from the bleed screw be a solid jet of coolant? Mine seems to catch on the sealing washer and spray everywhere.

 

[craiginuk]

Finally managed to remove all the trapped air from the cooling system after changing the thermofan switch on the radiator. Took the bleed screw on top of head out and replaced with a sawn off brake nipple (m8x1mm pitch) and a length of clear tubing running back into expansion tank. Ran engine up to operating temp and waited about 30 mins till the pipe ran clear. Much better than having litres of coolant spewing out bleed screw onto drive. A bit messy putting the original bleed screw back but overall a much cleaner solution. No more gurgling sounds from the heater and the temp gauge is behaving itself.