which thermostat do you recommend?

frankoman87

New Member
Aug 12, 2005
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Denver, CO
I've pretty much deducted that I need a new thermostat because my car has been running hotter than normal. It's running a little over the half way mark right around 205 to 210 degrees. I've heard that 190 is standard but I've also heard that some people have used a 180 and gotten good results.

Also, I need to replace my heater core. I know it is a pain in the ass but my mustang did not have an a/c from the factory and I've heard that it's super easy to replace if that's the case. Is it pretty simple to do with a friend and myself??
 
Another 180 vote. If it still runs hot, there are other issues which should be addressed.
The 180 does not fix anything - it simply prolongs the time it takes to reach 210* (random temp picked for an example).

Good luck.
 
Mr. Gasket 180 all the way. It' will be a long time before you ever have to replace it againg and they are pretty accurate.
 
I will stand by for the flames, but here are some facts. The factory says 190 to 195. There is a coolant temp sending (CTS) unit that talks to the the ECM and is part of the a/f ratio computation. So, at 180 you will run a little richer than if you are at 190 or so, whether there is a performance difference that is dyno proven or not I don't know, I will leave that one in the myth catagory until someone comes up with some factual data. A 180 will NOT fix a cooling problem. Assuming a properly set up cooling system, it will just let the engine run at 180.
 
fox_bodies_rule said:
I will stand by for the flames, but here are some facts. The factory says 190 to 195. There is a coolant temp sending (CTS) unit that talks to the the ECM and is part of the a/f ratio computation. So, at 180 you will run a little richer than if you are at 190 or so, whether there is a performance difference that is dyno proven or not I don't know, I will leave that one in the myth catagory until someone comes up with some factual data. A 180 will NOT fix a cooling problem. Assuming a properly set up cooling system, it will just let the engine run at 180.
Might want to check those facts.
The ECT (or CTS as you call it) needs to see ~178* before the puter goes to full CL fuel trim. A 180* t-stat allows this just fine. Before 180*, the puter can actually lean out the mixture, since the leanness brings temps up a smidge.

As for the rest, that was already said.
 
HISSIN50- I agree with all that you said; about the lean part, you learn something new everyday. The way I understood things is that it ran richer, as in cold start open loop mode, but what you say makes sense, gotta go get the ECM book out again I guess. My point is that at 180 you are very close to going into open loop as the stat cycles back and forth. This may not seem like a big deal for some but it gets below 0 degrees around here and you can definitely get the "cycling" thing going which can cause you to fail emissions if you are scheduled to test in the dead of winter. Call it tolerance stack for the ECT and the stat if you like, so 190 to 195 gives you the extra bandwidth. How do I know? flunked emissions, changed the stat only based on the test results, a great mechanic reading the a/f ratio real time and the fact that I wasn't throwing any codes. Great feedback, thanks!
 
fox_bodies_rule said:
HISSIN50- I agree with all that you said; about the lean part, you learn something new everyday. The way I understood things is that it ran richer, as in cold start open loop mode, but what you say makes sense, gotta go get the ECM book out again I guess. My point is that at 180 you are very close to going into open loop as the stat cycles back and forth. This may not seem like a big deal for some but it gets below 0 degrees around here and you can definitely get the "cycling" thing going which can cause you to fail emissions if you are scheduled to test in the dead of winter. Call it tolerance stack for the ECT and the stat if you like, so 190 to 195 gives you the extra bandwidth. How do I know? flunked emissions, changed the stat only based on the test results, a great mechanic reading the a/f ratio real time and the fact that I wasn't throwing any codes. Great feedback, thanks!
I see your point bud. Those temps you quoted are a bit specific (I could counter with the 115* temps we see here). I do know what you mean though (I grew up in Alaska).
There are many who do run two different rated stats in the winter vs summer.
Another thing some folks do is keep the 180 but shroud part of the radiator during the winter. Or let the car idle for a bit before going through the sniffer (in my experience, an idling motor, even in the middle of winter, will get warm eventually).

One thing we need to remember here - this is not black and white with regard to open and closed loop. Within 30-120 seconds of starting the car (most of the time, for most carsiwith HEGO's), the O2's light off. At that point, the ECT provides the puter with info on how much fuel trim is needed for the temps (this is closed loop though - just not full closed loop). But if someone ran at 170* (per the ECT) all day long, fuel economy would not diminish significantly IMHO (esp since we have adaptive strategy).
Most of us run the 180 stats to compensate for 15 year old cooling systems and cars.

I better post this - I have been typing it for 20 mins (with 20 interruptions).
 
I'm running the Mr. Gasket 180* stat as well with no problems. With a Griffin 31x19" 2 row rad, stock clutch fan, and a 50/50 coolant mix the stock gauge almost never moves from 1/3 up.