Matt O.

Installed new reservoir and heater control valve, flushed system numerous times with distilled water, and topped off with a 50/50 of Porsche pink stuff with distilled.

Car operates at normal temp, heater valve can be seen opening/closing as the temp control **** is changed, which is good. On full heat, air temp is warm to slightly hot, however upon revving the engine slightly, heats up dramatically.

Lower radiator hose was somewhat cool, upper was warm. Upon revving the engine, lower radiator hose heats up quickly.

Should I be concerned that the water pump is starting to fail and that the water is only truly being circulated when the engine RPMs are higher? It has been a while since I trouble shot the coolant system, apologies.

Thanks,
Matt

PS
That heater valve was a PITA.

harrisonrick

thermostat or rad is plugged?

Matt O.

Do you mean plugged as in clogged or plugged as in the themostat is not opening fully? I was thinking wp because I remember something about the pulley that the timing belt is attached to at the water pump sometimes malfunctions and requires more effort to spin the pump...

But I am open to any thoughts.

Luis de Prat

How old is the thermostat? How many times have you bled the system since replacing the coolant?

Matt O.

Not sure on the thermostat (just recently purchased the car). Records show timing belt change in 2007, and I can only assume they did the wp at the time as that is pretty standard (thermo along with the wp). Big assumption if you will.

Bled the system using pressure method. I will bleed again to double check and ensure no air in the system.

Thanks,
Matt

Luis de Prat

I know when I replaced the coolant in my 951 it took F O R E V E R to get all the air out. I must have bled the system 10 or 15 times until it was operating normally.

It must be that stubborn pockets of air form in the turbo pump cooling circuit. I'd definitely bleed it at least a couple more times. New thermostat isn't a bad idea, either.

In my experience, water pumps make a 'moaning' noise when they start to go bad. Is yours making any strange noises?

JET951

Hi Matt , a normal cam belt replacement on a 944 ( all) is just that , cam belt and hopefully its rollers main and secondary , same goes for the balance belt and its rollers , now when it comes to the water pump and for that matter any other part of the cooling system , that's very much up to the perceived condition of the water pump when the cambelt is off , meaning at that point in time is/ was there any signs of weepage or leakage from the pump ? or if there is more sideways play than normal in the waterpump pulley? ( indicating excess bearing wear) because if the answer is no then it will not likely to be replaced , particularly when the owner has a tight budget and all it came in for was a cam belt replaced because it had too .
Trivia Note : 944 water pumps ( all types ) last multiple cam belt changes as opposed to the 928 series (all ) that really must have its water pump replaced every cambelt replacement , the reason is the design of how the water pump is driven by their respective cam belts reflects their respective life spans , meaning the V8 928 cambelt puts more tension on its waterpump pulley = more tension on its bearing , and interestingly the special INA waterpump bearing( that lives deep within the both pumps) is the same in both pumps , but that's the only thing they share because everything else about both pumps is completely different .

So unless you eyeball a receipt / invoice that has the same vin or licence plate number on for identification and the invoice says waterpump and thermostat replaced in the last few years etc , then I would not assume .

Regards
BB

harrisonrick

Yes, clogged rad Matt...that's what I meant. I'd powerwash it from the inside out for sure off the car, and backflush it with the hose. I used the Prestone rad cleaner (OFF THE CAR ONLY) and let it sit in the rad on a plastic garbage container. After a few hours I backflushed it.

When I did that I couldn't believe the gunk that came out. Then I took the rad to a shop where they pressure and flow tested it.

Plus...it also sounds like perhaps the waterpump might be going out, and wasn't replaced as you'd hoped.

1 tip I've read....sometimes the impeller shaft separates from the pulley, and it spins slower than the pulley=poor circulation. Take off the upper cover and mark the waterpump pulley with a paintstick across the front. Then run the car...see if the line still matches up. That would indicate a pulley failure.

Also, look underneath and around the pump area, look for deposits of white calcium-like crusty stuff or rust...that will tell you the pump is weeping/leaking too.

Matt O.

Great posts. Good to be back in the 944 world with you guys. Thanks for the insight.

As for the maintenance, the previous owner (original) owned it for since 1989 and did MUCH of the work himself over the years, apparently a gear head. He did not spare any expense on parts, but did the work himself. That's why I don't have a receipt for the work for the waterpump, all I have is a receipt for all the required parts for the timing belt. More than likely, the WP was not done, but I think I'll call him and ask.

Thanks again,
Matt