Wtromb

Just a heads up to everyone running water only as a coolant. Water, especially destilled, deionized, or demineralized without antifreeze will do serious corrosive damage to radiators, heat exchangers, etc. Antifreeze contains rust and oxidation inhibitors that protect your cooling system. I teach locomotive diesel engine repair, these engines use water only with an additive that provides the correct levels of rust and oxidation inhibitors ((Nalco 2200 etc @ 5000 to 7500 ppm). The manufacturer has many photos of destroyed engine components and radiators with less than six months use with water only as a coolant.

Now to my problem, my 968 has a new water pump, new cooler thermo fan switch, and this time of year I'm always running at the top white line. I've bled the system three times and there seems to be no air in the system. Will the water wetter bring the temperature down?

sasilverbullet

nope on the water wetter, and top white line is TOO HIGH!!! Park the car and fix it... - simple answer

now the long answer - I just got thru going through this whole mess, so I know the horrors of troubleshooting the engine running hot...be patient, the answer will come. Here's some things to check:
1. Are you loosing coolant? Even running hot, you should not have to hardly add ANY coolant. If you have to add some each week, then you're loosing it somewhere. If you can't find the leak with a pressure tester, then you're probably loosing it through a head gasket leak. (sorry, i know that hurts) The way to see if it's the head gasket is to have a leak down test done. Also, when you open the radiator cap when cold, is there a lot of pressure still in the system? That's another indication you have a head gasket leak.

On my car, it was progressive - started loosing a little, no sign of leakage, then it took about 6 months to go from a little, to one day white steam coming out the exhaust! If that happens, immediately shut off the car and have it towed!

If you have NO coolant loss, and it's still running hot, then check the thermostat again.

And folks have put on BRAND NEW water pumps to find out they were bad...

Sorry to be the bearer of this news...

Hope you get through it cheaper than I did!

flash968

well, yes, and no

while i agree that watter wetter will not solve this problem, it does help bring down the temps

there are indeed a number of things to look at:

do the "squeeze the hose" technique, as you bleed the system - air pockets can be stubborn

as said, check for coolant loss

make sure both of your fans are operating at both stages

check for waterpump flow (recently a faulty timing belt tensioner was shown to be the cause of a waterpump failure)

check to see that the thermostat is opening and closing (these are known to fail)

you may need to purge and flush the system, if all components seem to be working

good luck

Wtromb

Thanks guys!

I'm not losing any coolant. No excessive pressure when the cap is removed. No change in the oil level. All fans are working properly.

Here's a run down of what happened. Early summer the thermo fan switch failed, I replaced it with an aftermarket switch that had a metal gasket that leaked, replaced that one with a swtch from Porsche that seemed to start the fans to hot. I didn't bleed the system. About a month later it really started to overheat, but I caught it before the temperature went into the red. I replaced the thermostat, and bled the system that helped a little, then the water pump immediately started leaking big time. I had the water pump replaced last week by a shop in Wisconsin run by a PCA member. However the temperature runs consistantly at or just below the top white line. I called a Porsche shop I respect a lot Eurosport and talked to their 968 tech. He tells me that his 968 runs at the top white line as well.

Yesterday i installed a new lower temp thermo fan switch and it now seems to be a little worse. I tried the bleeding gig several times. Maybe I still have air in the system? Do you squeeze the upper radiator hose to try and bleed all of the air out? That method is new to me.

Thanks Again!

josephsc

Two thoughts:
* did you remember to turn the cabin heater on when bleeding air?
* do you still have the underside plastic panel -- it's suppose to help direct air flow past the radiator.

Wtromb

Thanks Joe,

The panels are still in place. I did have the heater on. I elevated the car, turned the heater on, tried with the cap off, and the cap on, opened the 12mm bolt slightly at top right on engine and all i see is coolant coming out.

I only have 40,000 mile, but I'm starting to suspect the radiator. When the cooling fans kick on the temp doesn't drop a bit. However, no overflow, and i can remove the cap after 10 minutes. Could the gauge or sending unit be defective, and the engine isn't really that hot?

sasilverbullet

really sounds like a very stubborn air pocket...

and it's over 100 here a lot and my gauge doesn't get NEAR the upper white line..

SpeedBump

Could be a bad thermostat like I had on mine last month. Bought 3 more and tested them only one opened at the right temp, the other two were off by 10 degrees or so. and the one that was in my car for a week ended up not opening until about 25-20 degrees over.

The car has a really small radiator so once it gets heated up it is real hard to cool back down. You could also have a bad temp sensor (there are two) but you should get temps to compare to the guage before you replace them.

Wtromb

Thanks to all for the help.

I'm starting to think the gauge is bad. when I rap on the plastic in front of the gauge the needle falls. The car show's no signs of running hot.

sasilverbullet

hehe, there's the problem!

The famous Porsche grounds problem!!!!

When gauges do that, the grounds need to be cleaned - there's a how-to on the grounds somewhere on the site...

Wtromb

Thanks!

Does anyone know where the ground connections are that effect the temp gauge?

mikew968

I was using the standard 50/50 with my 968 and during DE's all was fine. As soon as I started racing i got very near the red during the race. I did 2 things: first i flushed the radiator at home and cleaned the fins and 2nd I started using water wetter. The temp dropped by about 1/4 so I am pretty sure WW does work. The other idea is too actually check the water temp temperature and possibly install an aftermarket water temp guage.

Good Luck,


Mike

sasilverbullet

ground connection for the temp gauge is up under the dash (of course!) near the left footwell.

Take it all apart, clean it well...

Jason Judd

My last event at Summit Point, WV showed my water temp's to be around 240~250 at times. The outside temp's were in the mid to high 80's and pretty muggy, too. We did some back-to-back sessions which really did not give the car any time to cool off...so at one point the car ran for 60 minutes with no cool down time.

I have an aftermarket gauge so I can get actual readings.

Of course, since I have turbo-charged the car, it tends to run hotter.

Jason

FRporscheman

Oops, I better do a flush and fill with an antifreeze mix!