Cooling System Issue

Fri Guy

Member
May 10, 2007
31
12
18
I'm having some issues on my 1990 Fox Body. It has a Mishimoto Radiator with Spal Dual 11" Fans and a old DCC FK35 Controller. I'm just getting the car back on the road after years of sitting in my garage. I would always still turn it on from time to time but rarely ever drove it. Few weeks ago I took it to my buddies shop so he could go through it and fix a few things. I had a small coolant leak at the timing chain cover so he replaced it with a new one and also put on a new water pump and thermostat while he was there. Before taking it to him my a/c wasn't working so always rode around with the windows down and while he had it there he was able to fix the a/c and a few other things. Since I've had it back I've always had the a/c on which kicks my fans on at 50% and it kept my car running between 200-220. This past weekend while I was driving it I decided to turn of the a/c and roll the windows down and shortly after in stop and go traffic I noticed my temp rising. It got up to 240 by the time I got in the driveway. I quickly popped the hood and noticed that my fans were spinning really slow so shut the car off and parked it back in the garage.

Since then I've been going through it and checking some things. I noticed that the coolant was a little low, not much so I topped it off. I let the engine warm up and the temp showed 190-200 and the fans did not kick on. They should be coming on around 180. I turned the a/c and the fans work but as soon as I shut it off the fans stop. So I took my IR thermometer and started taking some reading. When the car was completely cold I checked the top and bottom on both the drivers and passenger sides. I got 84 on top and 81 on the bottom which seems normal to me. I allowed the car to warm up again and once it got to 200-210 I checked again and was reading on the drivers side 145 on top and 105 on the bottom next to the radiator hose. The passenger side read 135 on top next to the hose and 90 on the bottom. Fans still didn't kick on.

So next I decided to check the temp sensor from the DCC kit after email Brian about it. I placed it in boiling water while I turned the car on and the fans were running at 100% like they should. I let the car warm up and placed the sensor back into the radiator but the fans didn't turn on. So for some reason the radiator is not getting as hot as the engine. I drained the coolant and removed the t-stat. Boiled some water and placed it in there and it opened as normal. I also purchased a new one and checked it as well and it was working as normal. I ran the garden hose through the radiator flushing it as best as I could until I saw clear water coming out. Installed the new t-stat in the correction direction and reassembled every back up. Added coolant and tried getting out all the air bubbles (which I'm not sure if I did a good job). I turned the car on checked for leaks and allowed it to warm up. Once again it got up to 200-210 and the fans still didn't kick on.

I next checked the temp with the IR thermometer on the intake right after the t-stat housing and it was showing around 190-195 and checked the temp at the radiator right next to the upper radiator hose and it was only around 160. Brian stated that it should be pretty close in temps between the two and said I still might have air in the system. Both radiator hoses were hot, the upper was a little hotter than the lower. So today I'm going to try burping the system again. Does the heater have to be on with air actually coming out of the vents or just turn the temp knob to hot? Any of you fellas had an issue like this? Brian from DCC has been great help at trying to get this fixed.
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
16,407
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polk county florida
You don't need to turn the fan on with the heat on to get the air out. I jack up the front end as high as I can when adding coolant to help get the air out. I also squeeze the lower hose a few times when refilling.
 

kendawg73

5 Year Member
Feb 5, 2014
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He put the correct water pump on right? There directional.... The foxbody one runs backwards... (belt on correct way)
 

Blown88GT

Founding Member
Nov 13, 1999
1,975
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Palm Beach Gardens, FL
Brian & I have the 1st 2 FK-35's. Both are still working. I recently changed radiators & had misplaced my "custom" jumpers for the FK-35. We figured it out.
I'm also thinking that kendawg73 could be right.
 

Fri Guy

Member
May 10, 2007
31
12
18
It was the DCC controller that was the issue and after tweaking it a little I was finally able to get the fans to come on when the temps reached 180-190. I've allowed it to idle after being warmed up for around 5 mins and the temps have stayed around 190 with the fans running. Thanks fellas for the help.
 
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