SC Running HOT

d3016

Registered User
Hey everyone:

This forum has been so helpful for me. I have another question. I have just completed a thermostat replacement, radiator has been re-cored and the vehicle still runs at the "M" in NORM. I have no idea what else to try. Anyone have any suggesstions? Thank you, in advance, for all your help.

D3
 
What year SC? Is it stock?

Might want to confirm that the single, push-on connector at the sender is clean and snug. Takes only a moment to check and minimum effort to rework.

  • What is the new thermostat rated at?
  • What pound cap & how old?
  • What did the radiator core look like when it was taken down?
  • How old is the water pump? Might have a badly corroded impeller...
  • Any chance your tensioners have aged and the belts are slipping?
  • Is the chin spoiler in place?
  • Air diffuser from the radiator to the back of the sway bar intact?
  • Auto trans?
  • Was the cooling system bled using the standoff at the thermostat housing?
  • Have a spare temp gauge to swap in?
  • Fan(s) working?
  • Brakes dragging?
  • May want to pull the plugs and see if any of them have been trying to burn coolant.
  • Has the coolant level in the overflow tank been riding high/low? What color is it? Tube from the radiator neck unobstructed?
 
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I have dealt with this as well. Mine always gets to the "M" and stays around it most of the time. I always though this was too hot, but I have checked the temp with a laser temp gauge, (pointing it at the thermostat tube), and my fan kicks on at the correct time... 220 degrees... and my car runs at the temp it is suposed to. I have just learned to ignore the fact that the gauge in the dash looks like it is too hot, because I know that it runs at the temp it is suposed to. Our stock gauges aren't real accurate either. Low speed fan should kick on at 220 degrees, and high speed at 228 degrees. But my car never gets hot enough to turn on the high speed.
 
my 94 SC has the same problem. when the gauge reads above the M the fan will kick on. and while stuck in traffic it gets hot too.
 
To be more specific, it is a '93 completely stock SC with about 100k on it. It is a 5-speed.

-The radiator cap is brand new(with re-cored radiator). The mechanic at the rad shop said it was 50% blocked.
-The t-stat is a motorcraft 197(stock)
-I used Prestone's 50/50 mix fluid and the overflow bottle remains at about half full unless I release the pressure from the cap.
-While filling, I did have the bolt memoved on t-stat housing to remove any air pockets.
-I have not checked the water pump. It looks like it could really be a PITA to get to and service. That job may be too big for me.
-The brakes are not dragging.
-I wish I had a heat gun to determine the actual temp.
-I did clean the heat sensor when I put it back on. I am wondering if I have a gauge issue, because the guage does move around. It sometimes goes from the "M" to the "N" and than slowly moves back up.

Thank you to everyone who responded. I hope this information is useful and will allow you guys to have more ideas.

Thanks again.
D3
 
To be more specific, it is a '93 completely stock SC with about 100k on it. It is a 5-speed.

-The radiator cap is brand new(with re-cored radiator). The mechanic at the rad shop said it was 50% blocked.
-The t-stat is a motorcraft 197(stock)
-I used Prestone's 50/50 mix fluid and the overflow bottle remains at about half full unless I release the pressure from the cap.
-While filling, I did have the bolt memoved on t-stat housing to remove any air pockets.
-I have not checked the water pump. It looks like it could really be a PITA to get to and service. That job may be too big for me.
-The brakes are not dragging.
-I wish I had a heat gun to determine the actual temp.
-I did clean the heat sensor when I put it back on. I am wondering if I have a gauge issue, because the guage does move around. It sometimes goes from the "M" to the "N" and than slowly moves back up.

Thank you to everyone who responded. I hope this information is useful and will allow you guys to have more ideas.

Thanks again.
D3

It sound fairly normal actually. Like was said our gauges are not very accurate. If it is at the M and goes down to the N it sounds like the fan is kicking on and doing its job.

I was concerned with my temps as well, but after having a long tuning session with Dave D when my gauge showed near the "M" it was around 195 degrees which he said was perfectly normal. These car came with that 192-197 thermostat and he said they came that way for a reason. Until it gets in between the M and Hot, he said I shouldn't have any issues, but I was still vervous sometimes, so I understand.

The other issue is if the radiator was 50% clogged, (Not sure how honest your mechanic is) then you would have to figure the block and coolant pasages are clogged as well which wil not help at all. Not sure if the block and rest of cooling system was flushed and cleaned out, so it is hard to guess, but so far it looks pretty normal.

Smitty
 
Here's what happens to me... My temp gauge goes from M all the way to the N only after the first time it gets to M after startup... what is happening is the thermostat is opening for the first time since startup, and all the coolant is allowed into the engine. That is why it shoots down to the N so fast. Then, as I drive more, it goes back up to the M, and then the fan kicks on when it gets to 220 degrees, then dropping the temp on the gauge to around the R. My gauge in the dash goes back and forth from the R and the M all the time. The fan kick on at M... drops it to R, and then shuts off. Then as it gets hotter and back up to the M, the fan kicks back on and repeats the process.

It sounds like this might be what happens to you as well. It is all perfectly normal. But if you can get your hands on a heat gun you should check the temps to be sure.
 
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My 95 SC auto is doing the identical thing you are talking about. I guess it's normal. At the M the fan comes on and then turns off around the O to R. It does get hot here in Northern Cali too. Today it was 103.
 
i think the most solid idea or advise is to either add or replace that with a real temp gauge so that you have a better read on whats going on
 
I have dealt with this as well. Mine always gets to the "M" and stays around it most of the time. I always though this was too hot, but I have checked the temp with a laser temp gauge, (pointing it at the thermostat tube), and my fan kicks on at the correct time... 220 degrees... and my car runs at the temp it is suposed to. I have just learned to ignore the fact that the gauge in the dash looks like it is too hot, because I know that it runs at the temp it is suposed to. Our stock gauges aren't real accurate either. Low speed fan should kick on at 220 degrees, and high speed at 228 degrees. But my car never gets hot enough to turn on the high speed.

I concur with this as I've experienced the same thing on my 95. M is OK. If I turn on the AC it will run a bit cooler because the fan comes on when the AC is on. It’s funny but on my 90 it never got above the N but the fan did run when it went into that range. This just goes to show you the differences between the temp gages.

Here’s an idea. If you want to be more anal about monitoring your engine temperature, I guess you could wire up an after market temp gage that’s graduated differently then the stock one.
 
Yeah I agree with that, my 90 SC never gets above N and the fan comes on the guage moves lower than N. More near the blue. Wierd

I concur with this as I've experienced the same thing on my 95. M is OK. If I turn on the AC it will run a bit cooler because the fan comes on when the AC is on. It’s funny but on my 90 it never got above the N but the fan did run when it went into that range. This just goes to show you the differences between the temp gages.

Here’s an idea. If you want to be more anal about monitoring your engine temperature, I guess you could wire up an after market temp gage that’s graduated differently then the stock one.
 
i kinow theres better ways to do this by i linked into the low side power for the fan with a relay. left the high side alone and while in city driving i can flip the low side fan on and the car run real cool, maybe even to cool. for highway drive it seems to never get hot enough to need a fan at all. somewhere in this forum u can find out how to bypass to low side internally was just faster and easier for me to run a relay :)
 
On my 89, there is no low speed fan.....

The high speed will kick in when the needle is about half way between the M and the red zone.....

The high spped kicks off when the neddle gets to the right leg of the M.....

However, when driving at highway speeds and in clean air, the needle is in the 12 o'clock position between the O and the R....

One of these days, I'll have to find the time to fix her....:p
 
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