New Thermostat and I'm still over cooling?

[jhammel85]

My truck is an 87 Ranger 4x4. Automatic w/ 2.9 V6.

When I bought my truck it seemed to run cold and I replaced the thermostat. The old one was stuck open. The collar from the inside of the thermostat broke and got wedged up in the thermostat, sticking it open.

So, I replaced it with a good ol' 195 Thermostat and everything was fine for about 5 days. Now its back to its old ways and I pulled the thermostat. Its fine! BUT...I can compress it with my hands. I shouldn't be able to do that should I? If that pressure can compress that thermostat then you know it's gotta be pushing right past like there is no thermostat at all.

What do you think? Should they be compressible by hand?

 

[Big Jim M]

I never tried to compress one with my hands.. BUT I do know they open from expansion NOT from coolant pressure. The spring is there to close them as the WAX PELLET inside the copper housing shrinks from cooler temps.
When the 195* is reached the amount of WAX inside the pellet expands some to open the gate. If the temp continues to rise the pellet expands more and opens the gate more. Etc. until the gate is open too wide. At that moment the gate starts to close a bit. But it all depends on temperature not coolant pressure.
Big Jim

 

[jhammel85]

Hmm...Thank you very much. I read that earlier but it didnt click that the pressure would not matter. Well if the thermostat was OK, why was it good for a few days? I dont believe I could compress it by hand before. Just seems odd.

Welp...If this really isnt the problem, does anyone know how to "test" the fan clutch? I checked it by feel with my brother in laws 4.0 in his explorer and the fan in my friends 2.3 ltr 4 banger in his ranger. Both "feel" like mine. Thats not really good enough though, I'm sure.

Any ideas??

 

[Big Jim M]

Your engine is most likely at the desired temperature.. I'd be looking at the coolant sender and gauge.
Big Jim

 

[piotrsko]

FWIW: I have bought defective thermostats in the past. the way to test it is to put it into a clear cup and add hot boiling water then watch it open. Stuff a candy thermometer in there and as the glass cools off and the thermostat closes read that temp, which ought to agree with the temp stamped on the package/thermostat plus or minus a couple of degrees

I'd also make my wife mad at me and use the candy thermo on other parts of the cooling system, unless you have one of those infrared sensing thermos, in which case of there is about a 15-20 degree difference between the top and bottom of the radiator, then it's working.

edit: if the heater is nice and toasty (about 120 degrees) then you have gauge issues.

 

[jhammel85]

Thanks for all of the help.

Yeah, I know the heat is warm but not melt your skin off hot that I had with a new thermostat!lol.

I know about checking it in water so I guess I could try that. I just figured it wouldnt tell me much if I know for sure that its opening. Still, I'll try it.

I plan to get mechanical aftermarket mechanical gauges. I just bought the truck in dec and figured when it got warmer I'd install the gauges. So I'm sure that once I hook them up we'll see where we are and what I need to do.

I appreciate the help!

 

[88_Eddie]

geez, it's amazing how many people are having coolant issues this winter. i'm currently going through the same thing, i replaced t-stat, water pump, ECT and now i'm workin on the heads/head gasket. my temp gauge still wasnt workin before i started on the heads. i'd start with the sender and then most def get a new water temp gauge, as soon as i'm done with the head gasket, i'm gonna get a new one.

oh and btw, when i replaced my t-stat i tried to move the new and old one by hand and couldnt do it, doesnt seem right that you could've

 

[jhammel85]

Yeah there is basically little to no resistance in the spring. Its very easy to compress. I should of kept my receipt...

Who knows..it could work to my advantage come summer!

 

[kimcrwbr1]

I would guess you should fix it before it gets hot out for one thing the computer adjusts the air fuel with water temp and the thermostat does two things it opens to maintain temp but if it opens too far the water goes too fast thru the radiator to cool it also and just steadily gets hotter. with it being cold out the water never heats up and when it gets hot out it wont allow the radiator to cool it spend the bucks for a good tstat for start then troubleshoot from there make sure it is sealed good any leakage around it will throw it off under pressure.

 

[jhammel85]

Yeah, I know its not good to run too cool. Of course I'd rather have it running at proper temp, I was just saying.

No leaks, its definitely seated properly. Like I said this is the replacement and the truck was good for a few days. I plan to spend the 10 bucks for a new one soon but I'm also going for new gauges. Everyone knows how bad the ford dummy gauges are. I'd like to know exactly what I'm running...not just NORMAL.
By the way, This was a stant Stat that I put in. I'm all about using motorcraft when available but it wasnt.

 

[kimcrwbr1]

does your temp sensor for the guage have only one wire if it does put a jumper wire to ground if it reads hot there is nothing wrong with the guage use it till u figure something else out the sensor provides ground to the guage

 

[kimcrwbr1]

also if you test the wire for voltage it should be a pulsing voltage key on or accy

 

[jhammel85]

Yeah, I should of mentioned that I tried that. The gauge itself works its just on the low side of things...just before the arch under the "L" IIRC

 

[kimcrwbr1]

all the guages have the same regulator so if it just the temp reading low yea it is the guage or a bad connection

 

[Capt Jay]

A lot of t-stats are bad on the shelf. Try a new one. I'd bet that your problems will be solved.