Cooling my 90 SC

Guy Montaquila

Registered User
Hi Everyone,
Thanks for reading. Just for background, the temp gage in my 90 SC has been reading around high end of the M in NORM at idle, so I replaced the t-stat, sending unit, temp sensor, radiator, hoses, a GM air dam and of course flush and fill, and the temp has not gone down at all. Here are the questions
1. I noticed that the wire from the sending unit is missing the connector or boot. Does that mean I could be reading the air temp in the engine compartment if the wire is exposed?
2. I also checked my pulley assemblies and according to the arrow, my belts could be bad, but they are new and tight. I don't get any belt slippage. Is my water pump not flowing enough at idle?
I will try to get pics.
Thanks for any advice.
Guy
 
There are two temp sensors, one for the gauge and one for the EEC. The gauge sensor has ony 1 pin and will not effect the temperature the fan turns on at.

Loss of the boot on the sensor wire will not effect the sensor reading.

Is your fan turning on when the temp gauge reaches the 'M' - this is normal even with a lower temperature thermostat because the computer controls the fan.

Aaron
 
Thanks Aaron. My fan does turn on when it reaches the 'M'. Its just weird that I never saw temps that high till recently and even after all the replacements, still no change. I was thinking of putting in a dual fan from the later model T-birds, but I am unsure if the alternator can handle it. Also does anyone know if the dual electric fan was used on non-SC t-birds also? Any ideas on how to get my SC to run cooler without running the fan constantly? Thanks.
Guy
 
Guy,
I'm battling the same thing you are right now as well. I'd prefer my car to run at about 190 normally. I'm thinking that the best bet to get it to run at that temp (read cooling fan kicks on at 190 to 195 range) is to get a tuner and custom chip which will control when the fan kicks on. You could try the fix to make your fan run all the time, but I don't feel too comfortable about cutting wires in my car. A chip can fix that, albeit for considerably more $$ too. AT first, I thought that my low speed (on the cooling fan) didn't work, but soon found out that it was working.

I also had a broken boot at the connection of the sending unit. I got a new sending unit and an eyelet to connect it. Been working well since, just a bit too high for my taste.
 
The computer controls the fan on temperatures so you have two choices:

1: disconnect the fan from the computer and get temperature controlled switches to control the fan.

2: Get an EEC tuner (or wait a few months till I finish mine) or chip and have the computer turn the fan on exactly where you want it on.

Aaron
 
Guy,
I got the eyelet at the same parts store, (O'Reilly's I think) but it did not come with any type of 'boot.' It's a typical electrical eyelet that you could pick up at any harware store as well. I did have a problem clamping the wire in the eyelet. It seems that my wire was (and still is) very brittle. I think that it broke off 3 or 4 times before I got it to stay ok. Good thing too because any shorter and I would not have had the temp guage hooked up!

If you were to look at a hareware store, you may be able to find an eyelet with a boot. I just wanted it hooked back up fast.
 
Guy Montaquila said:
Thanks Aaron. My fan does turn on when it reaches the 'M'. Its just weird that I never saw temps that high till recently and even after all the replacements, still no change. I was thinking of putting in a dual fan from the later model T-birds, but I am unsure if the alternator can handle it. Also does anyone know if the dual electric fan was used on non-SC t-birds also? Any ideas on how to get my SC to run cooler without running the fan constantly? Thanks.
Guy
Couple of notes. The temp sending unit on top of the thermostat housing is used only for the temp gauge. So if your temp gauge is working, you don't need to worry with it any further. The ECT is on the other side of the engine and sends temperature readings to the EEC which, as you know by now, turns on the fan. Your fan has 2 speeds.. a low speed which kicks in around the "O", but allow for variance in the gauges, and a high speed which kicks in normally between "r" and "m".
Let your car idle till it warms up with the A/C off and watch to see that the fan turns on. Note how fast it seems to be turning. The high speed setting sounds like it. The low speed you may not even hear inside the car. Now, turn on the A/C.. the high speed fan should start up right away.
There is one other thing to check, if you aren't seeing 2 speeds. The IRCM is the black box in front of the air cleaner. It has the 2 relays which cycle the fan. Its also possible that your fan motor has a problem.
As far as alternator ratings, the SC has a 110A mitsubishi unit. Should be plenty for a dual fan setup.
I'm surprised that a new thermostat and radiator didn't make any difference.
 
TbirdSCFan,
Thanks for the input. The fact that your fan turns on at O and mine at M worries me some, but its all relative. I guess it really doesn't mean anything is worng with the car, but maybe that my gage is off. According to the manual, the low speed fan comes on when the A/C is on, not the high speed. The high speed fan only comes on at high temps, like 230. When I let it idle, with the hood up, the fan turns on and off, keeping the temp gage around the M in NORM, but when I turn the A/C on with the hood up, the temp is around N. This just seems like such a wide range. I may be worrying over nothing, but it just gives me an uneasy feeling. I should put in a real water temp gage that gives real numbers, not a relative range. I guess I just thought, with all that work, and new parts, the car would not reach those temps. BAd assumption, considering how small the radiator is.
Guy
 
I have a 90 that runs in about the same range. As far as I know when the AC is on the fan runs all the time regardless of engine temp. I put a switch in the #14 wire and it works fine. If I'm in town I just flip it and run the fan on low all the time.

Found a good place for the switch too. It's just a Radio Shack toggle with a short lever. I don't know what that hole is for but the switch fit in there great. No drilling required!
 

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