What are the symptoms of a stuck thermostat, I replaced my water pump and thermostat about a year and half ago, about 2weeks ago my jeep started taking longer and longer to warm up, my heater is not working to well either, before it took 5-8 min to get up to temp which was roughly 200-210, now after 30min I'm sitting on about 130-140, is this signs of a thermostat issue or something else. Thanks

 

It does sound like a thermostat that is stuck open.

 

X2

Most thermostat's designed these days are designed to fail open. This will keep the vehicle from overheating as opposed to it failing in a closed position.

Not to say that one still can't fail in a closed position, but the design is intended to fail open.

If its stuck open, you have coolant cycling through the whole system at start up, Rather than it being closed allowing no flow until the engine is heated.

 

Makes sense to me it's what I thought it was, thanks for the confirmation guys!

 

Any particular kind or degree thermostat better than others?

 

Oh no.......that can of worms just got opened. LOL It came from the factory with a 195.

 

That's what I thought when I replaced it, I put a 195 back in it, I pulled a 180 out of it, what's recommended to put back in a 195 or something different

 

FWIW, we've been running a 180 Stant SuperStat for 4 years and the heater will make u sweat, gets good mpg, enters closed loop just as quickly as a 195 stat and runs like a top. Yes, I've been told I'm doomed because ours doesn't run 210.

 

The 180 u removed.....was it stuck open? Was it possibly a "fail safe" type stat?

 

To be honest I have no idea, I installed a new radiator last winter and while it was out I just went ahead and changed the water pump and thermostat while I was in there.

 

I'm aware of only one brand/model of stat designed to fail open and that's a MotoRad "Fail Safe" stat and the reason they fail open is because the motor is overheating. Basically a gimmick to sell stats. MotoRad sells other models of stats that are not the "fail safe" design. I don't believe Mopar sells a "fail safe" thru dealerships and I know Stant does not sell a "fail safe" stat.

 

Yup sounds like thermostat i had a fail safe before it got stuck open put back in the stock one works like a champ.

 

Djb, you are doomed because yours doesn't run 210. Anyway ct, you surely can't go wrong with a Mopar 195*. Be sure to put the hole up at 12:00. (I'm just ribben' Djb, he's an expert on cooling systems).

I ran a little cool for way too long with an after-market T-stat. It was built fine and functioned, but when I finally pulled it I found it was not seating quite perfect. Idk if it warped while in, or if I just didn't catch it on install.

 

I knew about MotoRad, and I was thinking Stant had another line of thermostats that were designed this way too. I did some checking though and find anything on it through them. I can't remember who the vendor was off the type of my I was talking to last that was demo'ing some thermostats.

Agree to some extent on the gimmick piece. I can see where it would fail open just bc of the overheating, but I would still rather it be opened than closed. I have a few t-stats fail in the open position before and the vehicle never showed any signs of overheating before failure.

 

I want a stat that's guaranteed to open......not guaranteed to "lock open" at X temp. If it never opens, then it certainly won't reach the point that it "locks open". "Locking open" just creates other problems. I haven't seen one that "guarantees it will open". The "gimmick" feature behind those "fail safe" stats is they're designed to "fail/lock open" before signs of actual overheating........like coolant boiling, etc. A motor can run hotter than usual from time to time, depending on driving conditions, but not hot enough to be considered as "overheating".

I'm unable to find any info that states the temp they're designed to "fail open". How would u test one for the "lock open" temp?