In the 50 degree nights I routinely drive my RS in now, unless I'm in traffic, the temp gague barely moves at all. Now, I know the gague is off because its barely in the red before the fan turns on (had 2 mechanics check operation, and its turning on at normal 225-230), but on nights like this I barely get any warm air out of the heat...so I know its running cold. In traffic, the needle moves up, then goes back down near to where it was once cruising again for more than a couple minutes.

Is the difference between a 180 and a 195 thermostat that great in temps like this? I'm running a 180 now, and am planning to switch to a 195. I sometimes wonder if its even getting to 180 sometimes, which means changing the stat won't really help much!!! I know one thing is hurting me...I'm running an open element, which obviously has no stove pipe to recirculate warn air. However, I've been running this for 2 years and it never seemed to run this cold last fall. I added this summer a high-volume Edelbrock aluminum water pump to help combat the heat I thought I'd be adding under the hood when I added the headers. Is this part of the problem too?

Or will changing the thermostat be sufficient? Like I said...I don't even know if its even getting to 180 on the open road because the air in the vents is lukewarm. Thanks to anyone who can help!

 

Jason,

Sounds like your thermostat is failing to open or is opening too soon. I recently put a Mr. Gasket High Performance 180 degree thermostat in my mild Olds 350 and it is very slow to warm up in cool temperature, and stabilizes at about 160*. Others using the Mr. Gasket hi po thermostat have seen the same thing.

I took it out and tested it in a pan of hot water and it begins opening at 150* and is fully open before 180*. It is also slow to close as the water temperature goes down. So, I would suspect a bad thermostat. I have gone back to a standard Stant thermostat that holds the temp at 180.

I have no experience with high volume water pumps, but it seems to me that the thermostat should still control the engine temperature by not opening until the water is just about at the thermostat rating (180* in your case).

John

 

From what you are describing sounds like a bad thermostat. I have had this happen in the past and it has always been thermostat. Also always kills my thermostat shortly after I flush my radiator.

 

Interesting...well, it is a Mr. Gasket High Perf thermostat!! I had a 160 originally in it when I did all the work this summer, and it was just too damn cold. I just changed it to the 180 not long ago.

So I guess I should bring back the Mr Gasket 195 I bought, and get a Delco 180 or 195?? Any thoughts are appreciated!

 

A properly functioning 180 thermostat should allow the car to heat to 175-185 within 5-6 minutes and put out plenty of warm air from the heater. My car is not on a computer so I don't have to worry about the computer sensors. Some of the computer controlled carbs might need to run hotter (195*+) for proper carb and emissions control.

Also, the Mr. Gasket has a small by-pass hole that allows some coolant to flow even when the thermostat is closed. Maybe this is for very high performance cars, I really don't understand what this is for, but could make the car slow to warm up.

I got the 180 Stant from Advance Auto and it is stamped USA, so not a foreign made part. I had the car on a long drive for the first time with this stat over the weekend and it warmed up quick, went to about 190 before it started cooling back down. Ranged between 185-195 for the first hour then generally stayed just above 180* for the rest of the trip (3 hrs.). Hope it settles out at about 180* all the time this winter.

John

 

why would you think it's failing to open? He said nothing about over heating or coolant boiling over.. that makes zero sense.. stuck open would make sense, which would cause the car to run too cool and never reach operating temp in colder weather, but a stuck closed thermostat would just result in it overheating in a short time..

 

89,

You are absolutely correct, stuck closed would cause overheating - not his problem. Got it turned around.

But the Mr. Gasket thermostate could cause the problem. The Mr. Gasket thermostat I used had a small bypass channel in it and that small bypass must have been what caused my car to warm up slowly, even with the thermostat still closed.

Sorry for the miss-statement, surprised someone didn't catch it earlier.

John

 

well thanks guys i have been having this problem with my 91 rs 305 tbi...