Clint's 944

I need help....

I am not a master mechanic, in fact..pretty much everything aside from regular maintenance I have learned, has come from my two Porsches and Rennlist! I have been lucky as I have usually been able to troubleshoot any problems based on the archives. I am not getting anywhere and previous posts just keep leading me to more problems. Thae car was great before this whole fiasco started. I am still oveheating...bleed bleed bleed and nothing but air.

So far I have replaced the Rad Cap, Radiator and now the thermostat. In doubt of my abilities, I took the old radiator and cap to a shop and they verified the they were bad. Yesterday, I went ahead and looked at the thermostat and it was in pieces, so I know that was bad. I still had a new one in the box so I replaced it. I am still overheating so I am assuming the waterpump is bad too.

What do you think is happening to my cooling system?
Could a blockage possibly cause so many failures at once?
Should I go ahead and replace the waterpump and see what happens?
Do you think this will probably be the last thing?
What's left that could possible be bad?

What do I do next!!! HELP!!

Thanks,
Clint

aeronautica86

are you losing coolant? does the overflow tank spit out a bunch of fluid when you come to a stop and turn the car off?

Izzy

Check your fan operation (fan switch?). With no fans the radiator is useless.

Royalty

/\ i had teh same exact problem, it was my fans not cutting on.

Clint's 944

Not losing coolant...unless I give it a big romp around the block. High RPM in the driveway does nothing,

Fan operation is normal....they come on when the needle reaches the third mark.

At high RPM the temp. will drop to about halfway. As soon as I let off the throttle, the temp goes up.

Waterpump?

PaulStewart

Do a compression check of the motor and a pressure test of the cooling system to rule out a leaking head gasket.

aeronautica86

so if you run the car pretty hard (ie get the coolant fairly hot) it will dump coolant? how much?

mgmarsh39

My overheating problem ended up being rust in the radiator. Had a fairly new waterpump but was ruined since that rad was bad. Cost about umm... 500-700 if i remeber correctly.

After having it replaced (radiator, thermostat, waterpump, fan relay) the car ran right in the center.

SoCal Driver

How do you get enough rust in a radiator to clog it up when most everything in the cooling system is aluminum? The exception being the water pump impeller.

Perry 951

Sounds like you still have an air pocket somewhere in the system. The higher flow from the higher RPM's helps overcome the pocket and mix the air back into the system. As soon as you slow, the air settles back out and blocks the flow.

Find a bumpy road and drive up and back a few times with the heat on full blast. Then bleed. Drive again and bleed. Do it until you don't bleed air anymore, then bleed again a few days later. It took the better part of 500 miles of driving bleeding every other day or so the last time I opened my system.

The water pump is direct drive so it should not cause a flow issue unless it stops spinning. In that case, you'll know it failed because the valvetrain will go with it.

SoCal Driver

As to the question of over heating; this can be a real pickle to figure out. The obvious being most of what has been mentioned. Bad radiator cap, temp switch, thermostat, head gasket. I'll add fan relay and a pin hole leak in one or more of the hoses usually at the clamps. The heater core could be leaking too.

If the head gasket is leaking the top radiator hose is usually hard from the over pressure. This will also blow out the radiator cap too.

As to bad water pumps; the impeller shaft bushing can be almost gone and they will still pump sufficent coolent through the engine. May leak out the front too.

I would be concerned as to where the pieces of the broken thermostat went to. These could be blocking the ports from the engine block at the water pump.

L8 APEKS

Why not take it to a shop and spend $30-$45 so they can at least pinpoint the problem?

Then you can determine whether or not it's beyond your ability or budget to repair it, once the shop tells you exactly what's wrong with it.

There comes a point where all the guesswork is just a waste of time. Drop it off and get a for-sure answer, so you don't have to worry about it anymore.

Clint's 944

Thanks for the response everyone..

Paul Stewart- Do a compression check of the motor and a pressure test of the cooling system to rule out a leaking head gasket.
I did the compressioin test already before and everything was perfect..really!

aeronautica86- so if you run the car pretty hard (ie get the coolant fairly hot) it will dump coolant? how much?
When running at high RPM (4-5K), the coolant will drop just below the minimum. When I let it idle it will slowly fill up the resevoir and then dump a small amount out the overflow tube. After a little while with the car off, it will go back down to normal.

Perry951- Sounds like you still have an air pocket somewhere in the system.....
That's what I thought back when I replaced the radiator. After that it was the same symptoms. Then I found the thermostat broken, and still the same symptoms. I have tried driving the car down some bumpy roads. I've done hard launches and brake tests. I've jacked the car side to side, up and down. Still, nothing comes out but air.
I can run the car at 5k rpms and open the bleeder screw and all I get is steam...The longest INTERVAL I have ran it is 20 minutes and I've done this 15-20 times. (neighbors love me!)
I have clamped the hoses going through the throttle body...air.
I have taken everyhose off and filled each one as much as I could...air.

Socal Driver- I was thinking a leak...but there is no coolant leaking anywhere. It's hard to tell if the top radiator hose is hard as it's a hard pipe (S2). The lower section of the top hose is no harder than the lower hose at normal operating temp. The thrmostat was flush in the housing. After I got the pices out I compared it to the new and everthing looks to be there. I did noticed that when the t-stat was out I stuck my finger on the pump and felt some black gooey stuff along the walls just inside where the thermostat would be.. It's a perfect thin ring and didn't protrude any deeper.

So, do you think the waterpump is fine and I have some "sticky air"?

Is there a way to verify flow in the cooling system?

Keep the help coming...thanks!
~Clint

Clint's 944

Here's the thing...

with my last 944, I had alot of shops refuse to work on it since they didn't know anything about it.
I had a reputable shop do the oil cooler seals on my N/A and after they finished, two weeks later, they kindly asked me not to bring it to them again. They were nice but they told me it was way too much shop time for them. I understood.

There are two shops in Myrtle Beach that advertise they work on Porsches. The first is a major ripoff. This is the same guy that wanted to charge me $800 to do a leakdown and compression test. He also offered to do my belts and rollers for a paltry $1300. The other shop can do it but I there is a two week waiting period and they are pretty far for a towtruck bill. If I have to I will but I'd rather not.

Belive it or not...there are only 3 PORSCHES in Myrtle Beach. A red 924, my 944 S2 and a 951. Nobody and I mean nobody ever works on these cars down here unless they are shady backyard mechanics.

I just can't believe it is this difficult!

barelyrunshalfthetime

7.2 My car runs hot/temperature fluctuates, what are possible problems?

A trick for getting most of the air out when refilling involves leaving the bleeder valve open while refilling, loading the system until the expansion tank is mostly full and then forcing the coolant through until coolant comes out the bleeder valve (how do you force the coolant through? You can perform "mouth to mouth" on the expansion tank, or you can use a coolant system pressure tester - a device which basically looks like a bicycle pump connected to a radiator cap). You may have to repeat the fill/pressurize cycle several times before coolant comes out of your bleeder valve. For all bleeding, make sure you crank the heater temperature control to the full open position or you'll be there forever trying to get the air out.


Check coolant level. Ensure that air flow to and through the radiator is not blocked. Make sure your water/antifreeze ratio is greater than 2:1 and preferably 1:1.

-www.clarks-garage.com (hope i am not out of line quoting this from him)

you can go there for more info if u need it, seems to me u should get one of those coolant system pressure testers and force the coolant through the bleeder valve like he says. idk if u have tried this yet or not but its worth a shot.