pauldvazquez

I replaced the thermoswitch today (with the grey body Wahler, 80-85/88-93 the same one that was in it to begin with). Moe, you are right, it is kind of painful.

Afterward, I thoroughly bled the cooling system. I ran the engine at idle (didn't take it for a drive because of crappy weather tonight). I watched the temperature gauge climb until about 1/16" below the red mark. NO FANS TURNED ON. I put it back on the ramps and pulled the thermoswitch plug and retested the relay per the Clark's jumper tests again- CHECKED OK again!

Any ideas people?

Thank you,

pauldvazquez

Today I double checked all the relay contacts in the fuse box and checked the new switch for continuity at the fuse box. Everything checked OK again. I tweaked the relay contact blades slightly to be sure all connections were making contact.

I took the car for a nice long drive, over an hour. I drove rural roads with 50 MPH speed limits, freeway sections where I maintained a 70 +/- speed and a section of in town traffic. During the rural and freeway speeds the temperature remained at just above the first white mark on the temperature gauge. Once I was in town the temperature stated to creep up. By the time I got through town, the temp was just below the second white mark. As headed out of town, with the speed limit at 45, the temp went down to where it had been for most of the drive.

Once I pulled in the garage, i opened the hood and let it idle so I could monitor the fan operation. The fans were not on when I pulled in the garage. After the temp got over the second white mark, with no fans on, I pressed the AC switch. Both fans turned on, low speed, as they always have. The temp stabilized somewhat, but was still trying to climb. I turned the AC switch off and checked the fans. Both fans continued to run! Also, the temp went up high enough for the red warning light to turn on. At the same time the fans switched to high speed! I was happy to see all this fan action happening, even though the temps were higher than they should have been.

I shut down the car and let it cool for about 20 minutes. I then bled the cooling system. I noted a few small bubbles, but not much air at all. I used a grease fitting in the bleed vent with a piece of clear plastic tubing connected to it (read that method here on Rennlist), which allows the coolant to be collected and recycled through the system. I have a water toy air pump rigged up with a pvc fitting and a couple of rubber O-rings to help provide somewhat of a seal to the expansion tank inlet. After a few pumps and after the few small bubbles were passed, the coolant kept siphoning through the system. I kept recycling the coolant back into the expansion tank, approximately 10 liters. No more air was bubbling through the tubing. I also had the heater valve open the entire time.

After I reinstalled the vent plug and topped up the coolant, I started the engine and let it idle. I have a multi meter that has a temperature probe function. Its a little funky, but at least I had something to measure temperature. I was monitoring the gauge in between monitoring the temperature at the water pump outlet to the radiator. At about 70+ degrees Celsius, the fans kicked on at low speed! YES! I was really happy to see that.

I let the car idle, monitoring the temperature guauge and the temp probe at the lower hose connection on the water pump. The fans continued to run and the temperature on the dash gauge stabilized about 1/16” below the second white mark and the temperature probe stayed around 82 degrees celsius. I let it idle for 20 minutes, and the temps remained stable. I am not quite ready to declare victory yet, but I think I might be out of the woods.

I ordered an infrared temperature gun to double check the temps later this week. I will report back.

Thank you,

vandal968

I had some air bleed issues after one of my cooling fans crapped out and I was boiling off coolant (AZ summer with AC). I've found that the easiest AND most effective way to bleed is to just drive somewhere then when you get home, just crack the bleeder valve a hair until it dribbles fluid (car running, heat on). This is definitely not the "correct" procedure because if you fully remove the bleeder, or if it breaks in-half you are going to shower yourself with scalding, pressurized fluid. However, if you've already made sure that your bleeder moves freely this is FAR faster, easier and more effective than doing it the "right way" which in my experience requires multiple attempts at 10-15mins each to purge the system.

Kill yourself, burn yourself, not my fault. I do it with a thick towel over it just in case. If things go wrong the only purpose of the towel is to buy you time to run away.

FWIW, my 968 which has always run in the middle of the temp gauge for 15 years, now runs a hair BELOW the low white mark which is where my 944 always used to run. I was never able to get it to run this cool despite multiple bleedings the "correct way" (from cold with rad cap off). Bleeding the dangerous way works better for me. Don't overtighten the bleeder, it doesn't take much.

cheers,
c

pauldvazquez

Vandal,

I will add your method to my memory bank. Hopefully I am over with this bleeding/cooling fan episode.

Thanks again for the reply,