My car is an 84 SE, 2.5L.

It appears my thermostat is not working, the car usually indicating a temp below the first tic on the temp gauge, and never really moving.

I did a parts search on AZ's site and I see several types of stats ... 195 degree, 180, 160, and 180 & 195 degree stats with a failsafe mode (locks open at 280 F).

What is the stock temp stat? Any really good reason to go lower/higher? Failsafe a good thing to have?

If I am running with an open stat, and never getting up to temp, I understand this can cause the computer to do things and not let the car run in its best mode.

What should I expect to happen ... would it possibly cause a problem code(s) to be generated?

Jeff

Believe the stock is 195. You need to get a new one in there because it is hurting your mpg if your running low.

If your temp light or gauge is working ok I would not bother with the 280 locking. You'll know long before that if you get that hot...

That's my op.

The stock temp is 195. There's no reason to go higher, and in my opinion no need to go lower. The failsafe seems pretty useless to me. Even if your engine survived a trip up to 280 degrees (which it wouldnt,) you'd only need to replace the thermostat so it would work right again.

Get a Stant # 45819 this is a good stat and factory temp 195
Don

195.
I have the failsafe, only because it is the ONLY tstat I bought of 3 (I did return the first 2- autozone premium, and a stant) that actually opened at the correct temperature. the previous ones both opened around 180/185. I quess there is a reason the failsafe is 3x the price of the others.

The problem as I see it with the failsafe one, is that once you overheat, the t-stat is now garbage. on the plus side, it locks open and if you add water on the road, you will likely not get the trapped air bubble.

I would get the t-stat locally. verify the opening temps with either a digital point n' shoot guage, or winaldl. I am not the only one who has had problems with the tstats not working at the rated temp.

It's worth mentioning that the ECM's temp sensor isnt 100% acurate eather. You shouldnt rely on any of the 20 year old sensors for precise info.

also the temp guage is notoriously wrong. I've found the best way is to verify that the ecm temp guage is accurate, then use winaldl to track the temp.
honestly, just letting the car sit there and shooting it with a digital thermal gun only confirmed the ecm readout was good, (within 5 degrees), but you won't be able to see the t-stat working properly with a digital. alternate is to recalibrate the temp guage and watch the swings which is hard to do while driving.

quote Originally posted by tjm4fun: The problem as I see it with the failsafe one, is that once you overheat, the t-stat is now garbage. on the plus side, it locks open and if you add water on the road, you will likely not get the trapped air bubble.

I assure you... the Thermostat is nearly always trash after an over heat. Overheat hyper extends the pellet that makes them function, often to the point the pellet is forced out of the capsule. It can do that with or without blowing the valve stem out. If the stem blows out, the Stat is likely visibly ruined and jammed. Even if the pellet doesn't visibly escape, the thermostat is extremely unlikely to ever work right.

Remember that if you have good pressure caps and proper mix... the coolant is not going to boil until around 265*F. This is way outside the normal operation of most thermostats. Frankly the fack one would lock open at something like 280 amazes me. If you ever manage to hit that kind of temperature you'll almost certainly have fried rings/gaskets and likely cracked something.

Second... unless you wait for Fiero to cool and add water thru the Thermostat housing you will have trapped air in the engine. There is no other way to remove that air except pull the thermostat.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurasic Park)

The Ogre's Fiero Cave (It's also at the top of every forum page...)

Jeff,
I would really have to wnder if your temp gage is correctly indicating your coolant temp. I have 2 84s, and ran one without a thermostat all summer one year, and the other ran for an unknown period of time without a rubber oring on it. Both ran around normal temps after they had warmed up. Since you live in the deep south, I would think your engine would also warm up to at least 190 deg F, even if the thermostat were stuck wide open. And if it is stuck wide open, you should be able to see this by removing it when the engine is cold.
When your ignition does the bulb test thing when you 1st turn the key on, the temp gage swings all the way over to the right-onto the stoppeg. This can make the needle move back to the left on it's stem , away from the position it should be in. Your engine may actually be running the correct temp, but the erroneously positioned needle may now register a misleading low temperature.

There are several write ups on how to correct the factory screwup that causes the bulbtest to deflect the needle against the stop. Might be one in The Ogre's Cave.

Hope this helps some with your gauge:

http://www.fierosails.com/tempgage.html

quote Originally posted by maryjane: Jeff, I would really have to wnder if your temp gage is correctly indicating your coolant temp.

Yea, I'm starting to think this is the case. I need to do some troubleshooting at the temp sensor, etc.

I'm also delving into the WinALDL stuff ... what a great tool that would be!


Jeff

quote Originally posted by DreamerZZZ: Yea, I'm starting to think this is the case. I need to do some troubleshooting at the temp sensor, etc. I'm also delving into the WinALDL stuff ... what a great tool that would be! Jeff

This helps alot :

http://www.aldlcable.com/

http://winaldl.joby.se/