924Board.org

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

OK, so I got my car back from its "cooling system refresh", including new Performance Products radiator, H20 pump, t-stat, and hoses, and the cooling is worse. Here's all the clues I got, please give your theory.

The radiator leaked on arrival, due to poor solder joints between core tubes and end tanks. The rad was taken apart, and all joints were re-done. The mech said the old radiator had a lot of deposits. The AC consensor was damaged and left off (presumably giving better airflow to rad). My highest temp on the track used to be the third mark, now it slowly creeps into the bottom of the red (then I stop). If I keep the revs down, I can keep it out the red, but just barely. The bottom hose blew off while lapping. . .loose clamp, I believe. Both fans are coming on together at second white mark.

I am tempted to start troubleshooting by having the old rad serviced and reinstalling it. I am also curious as to whether the t-stat might have been installed facing the wrong way.

Any other ideas? Or questions?
_________________
Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

steeny · Posted: Sat Jun 23, 2007 10:58 am Post subject:

have you tried bleeding the air out of the system again?
_________________
1978 924 N/A
she's gone.....

Lizard · Posted: Sat Jun 23, 2007 11:09 am Post subject:

could be air in the rad, too lean of a mix, or you could have some piping/hoses that are blocked. Take off the steel line which runs under the intake manifold and look in it to see if it is plugged at all.
_________________
3 928s,

Tigger937 · Posted: Sat Jun 23, 2007 12:25 pm Post subject: Re: Overheating Brainstorm. . .

Min · Posted: Sat Jun 23, 2007 1:12 pm Post subject:

From your description, it seems that a bit of guess and check is in order, we can assume all your new hoses are ok, your new water pump is probably ok. So what else did you change? radiator and t-stat. The other options are of course that the air was not bleed out of the system properly. So, Bleed it first, then swap in the old t-stat. Then based on those results, decide what to do next. Not a whole lot can go wrong with a rad so if its not visibly leaking, Its pretty much gotta do its job.

Min
_________________
Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

endwrench · Joined: 07 Dec 2002 Posts: 1631 Location: Victor, Montana

Long shot but I have seen it happen before. Is the water pump new or rebuilt? I have seen wrong impellers put on or put on backwards. You just need to compare to the old one.

I don't know about the 924 heat gauge in general but mine is actually running about 210° at the 3rd mark. 1st mark is about 170° and the second about 190°. This was measured with an infer-red.

A slow-blow head gasket will do the same

Todd
_________________
'79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!....

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Tigger937 · Posted: Sun Jun 24, 2007 1:40 am Post subject:

Just thought of something, make sure your cooling fans are rotating in the proper direction, it's easy to get the wires swapped. Also, might verify the cooling fan switch is operating properly. Both fans should switch on at or before approx. 2nd (middle) white mark on the temp. gauge depending on temp. rating of the switch you have installed.

Min · Posted: Sun Jun 24, 2007 2:10 am Post subject:

endwrench · Joined: 07 Dec 2002 Posts: 1631 Location: Victor, Montana

A CO test on the cooling tank would give you indication of a blown gasket or the best way may be to just apply air pressure to each cylinder and look for air bubbles in the overflow.

Todd
_________________
'79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!....

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

462avi · Posted: Wed Jun 27, 2007 1:00 am Post subject:

How does the car run on the street, when you are not pushing its limits? The reason I ask is what if it is not a cooling system problem? How does your oil cooler look? Have you flushed it out? I would think that if you were to have a partially clogged oil cooler it is possible to see high engine temps. Also with the system bypass valve you may not see an indication of an oiling problem. Somewhere I remember see an article on engine oil and the effect it has on cooling. The water cooling system is basically for cooling the head and around the combustion chambers. The rest of the engine is cooled by the engine oil. Its worth a check
_________________
2005 C230K
2002 grand cherokee with 4.7L

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Do you have an oil temp gauge? If not, you can buy a replacement dipstick with a temperature gauge built into the handle, might be worthwhile to see if your oil temps are getting too high.
_________________
1987 951 - M193 Version for Japan

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

The car does fine when being driven normally. I just got back from visiting Khal and Keno in BC.

I think the oil cooler is functioning. . .it gets too hot to touch when the engine is warm.

I am thinking now it has to be the "performance" radiator I installed. . .I'm going to have the old one serviced and put it back in for testing. It sounds odd, but maybe it isn't flowing enough. . .it did have problems in terms of assembly. . .
_________________
Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

Khal · Posted: Thu Jun 28, 2007 4:12 am Post subject: