Overheating

J

johnwartjr

Registered User
Well, I'm not quite overheated, but have a problem.

95 SC auto, approx 125k. Original thermostat and water pump.

Earlier in the summer, one day I got a check gauge light with the temp gauge in the dash all the way over to H

Turns out the radiator fan was bad. Replaced that and all was well. Only drove it home with the problem, and with the air off and the windows open, was fine.

Car has a ~ 5 year old radiator (all metal) that was repaired last year when the all metal radiator sprung a leak. I tend to drain and refill the cooling system about once a year.

The car is not losing coolant, the overflow bottle stays where it belongs.

The fans are still spinning just fine on either side of the radiator.

On a 90 degree day, the climate control thermometer shows about 6-7 degrees hotter than it really is. If I sit in a parking lot with the A/C running, such as waiting for someone while they run in a store, the air starts blowing warm after about 5 minutes and the check gauge light turns on. If I get the car moving and get some air flowing over the radiator, it drops down to just over the middle of the temp gauge and the air runs effortlessly.

But, before the problem, the needle was always in the middle - never budged toward the hot side.

I'm not sure where to look next. I am not losing coolant. Could it be a water pump? Thermostat?

I can swap parts just fine, and can test parts with directions, have many tools at my disposal.. but am not sure where to look here.

Any ideas?
 
johnwartjr said:
Well, I'm not quite overheated, but have a problem.

95 SC auto, approx 125k. Original thermostat and water pump.

Earlier in the summer, one day I got a check gauge light with the temp gauge in the dash all the way over to H

Turns out the radiator fan was bad. Replaced that and all was well. Only drove it home with the problem, and with the air off and the windows open, was fine.

Car has a ~ 5 year old radiator (all metal) that was repaired last year when the all metal radiator sprung a leak. I tend to drain and refill the cooling system about once a year.

The car is not losing coolant, the overflow bottle stays where it belongs.

The fans are still spinning just fine on either side of the radiator.

On a 90 degree day, the climate control thermometer shows about 6-7 degrees hotter than it really is. If I sit in a parking lot with the A/C running, such as waiting for someone while they run in a store, the air starts blowing warm after about 5 minutes and the check gauge light turns on. If I get the car moving and get some air flowing over the radiator, it drops down to just over the middle of the temp gauge and the air runs effortlessly.

But, before the problem, the needle was always in the middle - never budged toward the hot side.

I'm not sure where to look next. I am not losing coolant. Could it be a water pump? Thermostat?

I can swap parts just fine, and can test parts with directions, have many tools at my disposal.. but am not sure where to look here.

Any ideas?
Click to expand...

How much of the radiator was sectioned off after it was repaired? How old are the hoses? Do you ever run the heater?
 
johnwartjr said:
Well, I'm not quite overheated, but have a problem.

95 SC auto, approx 125k. Original thermostat and water pump.

Earlier in the summer, one day I got a check gauge light with the temp gauge in the dash all the way over to H

Turns out the radiator fan was bad. Replaced that and all was well. Only drove it home with the problem, and with the air off and the windows open, was fine.

Car has a ~ 5 year old radiator (all metal) that was repaired last year when the all metal radiator sprung a leak. I tend to drain and refill the cooling system about once a year.

The car is not losing coolant, the overflow bottle stays where it belongs.

The fans are still spinning just fine on either side of the radiator.

On a 90 degree day, the climate control thermometer shows about 6-7 degrees hotter than it really is. If I sit in a parking lot with the A/C running, such as waiting for someone while they run in a store, the air starts blowing warm after about 5 minutes and the check gauge light turns on. If I get the car moving and get some air flowing over the radiator, it drops down to just over the middle of the temp gauge and the air runs effortlessly.

But, before the problem, the needle was always in the middle - never budged toward the hot side.

I'm not sure where to look next. I am not losing coolant. Could it be a water pump? Thermostat?

I can swap parts just fine, and can test parts with directions, have many tools at my disposal.. but am not sure where to look here.

Any ideas?
Click to expand...

Check your AC condensor (In front of the rad) for clogged/bent fins do you see any bubbles in the overflow tank when the car is running? (Sign of HG failoure) is the car running all right? A lean condition (partally clogged injectors) could cause overheating. Is your high speed relay turning the fan up on high when the car starts to get hot?(I think these cars have a 2 speed fan)
 
Last edited:
Will have a look tomorrow and report back

Something else odd it's doing, regular AC blows harder than max AC.
 
rickbtbird said:
How much of the radiator was sectioned off after it was repaired? How old are the hoses? Do you ever run the heater?
Click to expand...

No clue on the sectioning, I dropped it off at the shop and picked it up when they were done.

The hoses were replaced when the rad was new 5 years ago.

Heater only gets run in the winter.
 
johnwartjr said:
No clue on the sectioning, I dropped it off at the shop and picked it up when they were done.

The hoses were replaced when the rad was new 5 years ago.

Heater only gets run in the winter.
Click to expand...

Well if the radiator was repaired, I'd question that first. Depending on the repair, it could be the issue. I've seen repairs that have made the radiator capacity less then the original.

5 years on hoses could be an issue. That's old but again they could be ok. Check them for leaks and rot. They could even be clogged.

Run your heater to insure coolant is running through it and watch you temp gage while it's on. It could add to the cooling time.
 
The puller fan (behind radiator) is a two speed motor. It might be the case that the low-speed winding is shot. Sitting at rest and turning on the air/heat should cause the low-speed fan setting to activate (i've used the defrost/floor and just the defrost setting to force my fan on before). It will remain on until you go faster than about 45 mph then it turns off.

From a previous post on sccoa, I think the low-speed activates around 212 degrees. The high speed is around 235 degrees. When the high speed activates, it de-activates the low-speed winding. I think the pusher fan (front of radiator) is tied in with the high-speed activation but i'm not sure.
--Fred
 
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