Porsche Enthusiasts Club Forum

Thanks to the almighty help of Keith aka avants2turbo, we spent a day and and evening yesterday pulling apart my car to replace the oil cooler seals, radiator and fan switch. We had to drain both oil and coolant to do this, so it was a mini service as well. After considerable swearing, all went back together.

We filled her up with coolant, leaving the bleed screw out. But here's the problem:
The radiator and expansion tank remained cold, the temperature gauge gradually moved into the red, and hot steam spewed out of the bleed screw, but no liquid.

The reason for replacing the radiator was a leak, which when hot, would issue steam, so hot coolant used to reach the radiator, expansion tank and bleed screw. So we can't understand how either the water pump or thermostat could have broken in this time, as they clearly worked before.

I'm guessing that it still has a massive airlock somewhere. I have seen recommendations that a pressure tester on the expansion tank is the best way to bleed it.

On the plus side, the oil and water are no longer mixing, and the oil pressure sender fixed itself!

HELP! Any guesses?

Assuming you left the rad cap off when initially bleeding it? if not may be thermostat.

Rich

Yes, and the heater was pushed to hot, although I can't remember if the air inside the car was hot or cold.

944 are always a pitta to bleed the coolant system. Some garages actually force the air out by pressurizing the system.
Have you tried all the usual stuff like running the car up to temperature with the filla cap off ? filling the system with the car facing uphill? loosening a hose at the highest point just past the heater matrix ?etc.
I would remove the thermostat and make quite sure that it is fitted up the right way for the flow and that it is opening at the correct temperature. You can cook it in a saucepan on the hob if you have a suitable thermometer .

is it possible your pump impellor has come off the shaft ? or you have a collapsed hose inner lining ? have you checked you have circulation when running ?

We ran it very hot to a point when I was scared to keep it running.
Do you mean running it with oil filler cap off? Expansion tank cap was off anyway.

Here's another issue:
Top of the thermostat circlip just happens to be aligned in such a way that neither Keith or I could reach it with the circlip pliers. So somehow, the circlip has to be pushed around, or the whole pump taken off. Just for clarification, does the circlip squeeze inwards or outwards to remove?

How do I check circulation?

Inwards, as it's an internal circlip.

Inwards, the stats are a pig to remove, even with the pump out, with it on, nearly on impossible!
This is an air lock. They are pigs to bleed especially with a new dry rad. You need to open the bleed screw completely & squeeze hoses like mad. Also pour some coolant in through the bleed screw hole. Slackening the hoseclips & burping air out sometimes helps as does filling the reservoir above the full mark. AT extreme levels then jack the front of the car up to assist the air out.

Thanks Mike and Jim. Jim I am especially happy with your confidence there! Do you think a pressure tester on the expansion tank would help at all?

Might very well do, I've never done it from bone dry, but even then it is a Royal PITA! What would help is a drilled through bolt the same size as the blled screw with a pipe & funnel on it. So you can pour coolant in & get a pressure head.

Peanut, you're great. Perfect explanations. I'll check the manual.

To reassure everyone, I did switch it off when it was getting too hot.

you might find Rick' s Cannel site helpful for manuals and schematics.
http://www.cannell.co.uk/Manuals.htm
.

here we go http://www.paragon-products.com/944_Cooling_System_s/358.htm

Thanks, I have this: http://www.9ss1.dk/porsche944/garage/owners83.html

heres a good solution to hard to bleed coolant systems on Paragon's website

http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/314947-best-way-completely-bleed-944-cooling-system.html

You need to bleed the coolant system with the engine off - overfill the expansion tank & be patient, wait till coolant starts to come out of the bleed screw. Ideally you want the car pointing uphill. The heater valve should be open (default is open) but switch the ign on & turn heater to hot if in any doubt.

Once you have coolant dribbling out of the bleed set the tank level to max & tighten everything up & run up to temperature (with heater on hot), if it looks like its getting hot before the stat is open (ie cold rad) then stop, cool and bleed again. Giving the engine a few short, sharp revs whilst warming up can help shift any trapped air - you will know if this is the case as the heater will blow much hotter air whilst revving than at idle.