Motor running too cool

Raven

Here - watch THIS!
Joined
May 24, 2001
I don't know if this is due to a bad (stuck open/opening too soon) thermostat or if it's because I recored the radiator this summer (with a high flow/efficiency core) but regardless, I can't seem to get a coolant temp above the mid-140's right now.

Ambient temps are running in the 20's so I know that has something to do with it but going down the highway, even at 45* ambient, the car can not get much above the low 150's*. The bigger problem is that the computer will not lock the converter until the coolant temp is 151* so I end driving a lot of miles with an unlocked converter.

Is this a thermostat issue? I pulled the t-stat and dunked it in hot water that I measured the temp with - it seemed to work as it should and it was not stuck open (at least after I removed it). So, should I just order a new thermostat or is this something else? Maybe I should just block off part of the radiator? Today, the ambient temps were in the low 50* range and the highest the coolant temp got to was 160* and that was after sitting at a stop light. :confused:

Is it 'too much' radiator, bad t-stat, or some other weird issue I haven't even considered?
 
I am having the same "problem" with the 87 I just bought. I use the Scanmaster and running around town it is near the thermostat rating of 160. Never gets above 161. On the hiway to Albuquerque this past weekend, it would hover around 137 and going up hills reached 148. Converter stayed locked up but heater was matching the reading. Someone mentioned it was the F-body radiator and dual fans but it should never be that low. It should be as low as the thermostat unless stuck open. :confused: Otherwise mine works correctly.
 
it wouldnt be a radiator issue. if your thermestat is functioning properly it wont start to open untill whatever degree stat you have. the lowest stats around are 160s- alot use 180. so even if you had a 160- it should atleast hit 160 then cool down. so untill it hits the stat temp- the coolant will only cycle through the engine heating it up. i would say replace the stat- its winter so through the stock 190 in :)
 
Raven said:
I don't know if this is due to a bad (stuck open/opening too soon) thermostat or if it's because I recored the radiator this summer (with a high flow/efficiency core) but regardless, I can't seem to get a coolant temp above the mid-140's right now.

Ambient temps are running in the 20's so I know that has something to do with it but going down the highway, even at 45* ambient, the car can not get much above the low 150's*. The bigger problem is that the computer will not lock the converter until the coolant temp is 151* so I end driving a lot of miles with an unlocked converter.

Is this a thermostat issue? I pulled the t-stat and dunked it in hot water that I measured the temp with - it seemed to work as it should and it was not stuck open (at least after I removed it). So, should I just order a new thermostat or is this something else? Maybe I should just block off part of the radiator? Today, the ambient temps were in the low 50* range and the highest the coolant temp got to was 160* and that was after sitting at a stop light. :confused:

Is it 'too much' radiator, bad t-stat, or some other weird issue I haven't even considered?

I'm just south of you, and last week my engine temps were in the low 160s with a 180d thermostat.

Might call your chip supplier, and have him do one with a lower TC enable temperature. I'd have to look but mine's like 90d. I think they just use a high temp., to get the engine temp up a little quicker.
 
Once up to operating temperature, the coolant should remain within a few degrees of the thermostat's rated opening point. If your 160 thermostat is unmodified (no bypass holes added) and your car runs in the 140's, your thermostat opens too soon or is stuck in the open position.

Is it possible that the temp gauge you are using is faulty? On warm-up, do you see the temp cycle up to the thermostat's temp, drop when the stat opens and then begin to climb again towards 160 degrees?

I would replace the thermostat with another 160 and see what happens.
 
RKHiPerformance said:
Once up to operating temperature, the coolant should remain within a few degrees of the thermostat's rated opening point. If your 160 thermostat is unmodified (no bypass holes added) and your car runs in the 140's, your thermostat opens too soon or is stuck in the open position.

Is it possible that the temp gauge you are using is faulty? On warm-up, do you see the temp cycle up to the thermostat's temp, drop when the stat opens and then begin to climb again towards 160 degrees?

I would replace the thermostat with another 160 and see what happens.

If the car is not moving (letting it sit to warm up) the coolant will go up to the 150's and eventually (s-l-o-w-l-y) it will get to 160 or so. However, as soon as I start driving (and if it is really cold out, say in the 20* range or so), then the temp will steadily drop off to the 140's if the road speed is fast enough. I've ordered a new 160* t-stat and will replace it as soon as it gets here.

I'll know then.
 
You could just jumper the ALDL (w/wire & switch) and lock the converter when you want to. Just remember to unlock when coming to a stop.

Gary
 
I'm mystified. With a properly operating thermostat, it should matter not what the outside temps are, the engine will operate at or very slightly above the thermostat setting. Occasionally slipping below that when coasting in cold weather if the t-stat is slow in reacting. Engine temps should always be at about what the t-stat is rated at.
Even with one of the most incredibly efficient cooling systems available such as those on turbo diesel light and heavy duty trucks, the engine still operates at the thermostat setting.

The only thing I can think of for your systems not operating at proper temps is a somewhat faulty thermostat.
 
Turbo Dave hit the nail on the head and just as I suspected. It was indeed a faulty thermostat. I replaced it with a new 160* from Kirban's, along with a new stainless T-stat housing and the operating temps are completely normal now, even in 14* ambient temperature!

The bottom line is that the old one must have been opening too soon in the car, most likely around 140*. I drove the car this morning with the old in and the MOST the car would warm up to was ~145* in the frigid Ohio air (14*). After installing the new one (yeah, it was damn cold in the garage!), the temps were normal, holding around 160* no matter how fast I drove.

And the heater is a LOT warmer too! ;)

Thanks for all of the replies. If YOU have a motor running too cool, don't waste time - just get a new thermostat, no matter what it appears to be doing in a pan of water. You'll be glad you did.
 
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