Mild Ambiguous Cooling issue??

EatonEmployee

Registered User
I have a 93 SC with 100k. It was like a new car when I got it 4k miles ago. It has a tendency to run warmer than I like at idle after driving or under load with the AC on. The car can easily cool itself. It has a new 180 thermo & radiator just done. Sometimes it cools itself just fine but often not. It will lurk just at the end of M in norm when I stop. I don't like this and getting an actual laser temp of 221-225.

The car can cool itself when it wants too. It's some kind of control issue. Something that tells when the car to cool isn't functioning quite well enough. Besides the ECU is there an extra control unit for the cooling system. Like the fan isn't coming on when it should. If it creeps when I stop. I often turn the AC on when I'm stopped & the high speed fan immediately cools the car back down to N. It never gets away from M but it slides on the very edge. Then somedays its just perfect. I don't want to dance with this issue when I'm dealing with different medals between block & head.

I know there is a fix & I'm eager to hear the experts point me in the right direction. Thanks............Lincoln
 
It's time to troubleshoot - but I'd almost lay odds on the low fan relay in the IRCM.

But it may not be, that's just a guess.

RwP
 
Possibly ECT sensor?? Does motorcraft make one? I've replaced many Partstrain/Rockauto etc parts that are bad out of the box. You DO fet what you pay for. I got 3 bad multifunction switches as you know are cars are famous for this as well as the pigtail.
 
If you have access to a code scanner try a key on engine off test. If the fan cycles to the high speed and low speed mode then the ircm is functioning normally. Running at the "m" in normal is OK. That's where all three of my sc's would hover on the temp gauge. The other thing to remember is that our factory temp gauges are junk and aren't very accurate. The normal on some cars will vary from car to car. If you are real concerned about it. Get yourself a digital non-contact thermometer (39 bucks at harbor freight tools) and take some temp reading of the tube (the one the upper radiator hose connects to) coming out of the thermostat housing. They should be the hottest water temps. That will give you an idea on how hot the engine is actually running.
 
Last edited:
In the stock tune, the fan isn't set to come on until ~220 degrees, unless the A/C is on. Changing the thermostat won't do much without also changing the tune.
 
Nothing is wrong, that is just how the car runs when you have a mismatch between coolant thermostat and fan programming. The fan doesn't come on until 220 deg unless it's commanded on early by the AC or defrost.

If you put in a 180 thermostat but don't change the programming in the EEC, then the engine will run even hotter than stock because the coolant will be allowed to circulate without any fan activity thus heat soaking the radiator and surrounding components making it even more difficult to cool than normal.

With a 180 deg thermostat you have to get the EEC reprogrammed to bring the fan on at 190 deg or else run the fan all the time.
 
What dave said.. except you might just put the stock thermostat back in. I use the 192 degree thermostat in Texas.. no problem.

OK, so thats not entirely true.. I wired in a take-control fan switch on the dash, with an LED to tell me when the fan motor is getting power, just in case in all 3 of my SCs. I rarely need it in my 2 autos, but in my 5 speed I use it all the time.

If anyone is interested, I used a DPDT 3 position rocker switch (which was not easy to find) spliced into the wires running to the IRCM from the EEC. LH position is EEC control, middle is low speed on, RH is high speed on. The switch wiring was done under the dash.. nothing under the hood.

I wired a small green LED just to the right of the switch directly to the fan motor. That wiring goes through the firewall.
 
yeah, I got actual laser readings at the thermo. 223. I'm one of the best mechanics I know but I also respect knowledge and experience. I task can be impossible or 2 seconds depending on knowledge. This is why I appreciate all of your collective knowledge. This forum and all of you are invaluable. Thanks.

My car is perfect I'm just being picky. I think I'm going to sell it stock. I've never seen one as clean or unmolested as mine. I've had it dyno'd & it did better than OEM with nothing done and 100k. Someone will hopefully have a nice car. I drive a 350Z & need some dental work.
 
Back
Top