Should I or Shouldn't replace t-stat ???

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ZooKypr

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Looking to do some general maintenance next month, plugs, oil change, clean carb, fuel filter, replace coolant...Its been about 10yrs since I put my Robert-Shaw t-stat in and was figuring on replacing that too since I'll be draining the coolant out. Do t-stat need periodic changing or "if it ain't broke, don't fix it" theory apply here fellas? I did notice lately that it may not be opening up to drop the temp like it used to. I never goes over 195/200 but usually the t-stat (180) will open up and drop to 180 regularly but not so lately. Maybe I just didn't pay attention to it before since it wasn't on the maintenance list.
 
since you are draining,might as well flush and throw in a new stat.they are only a few $$
 
If you do replace it,, ask for a "fail-open/safe" thermostat..

If it fails "open" you drive home with a cold heater, and change the stat..

If it fails closed,, you could have a serious overheat,, and a long walk/tow home..

hope it helps
 
Since you think it may not be operating properly and you'll be draining the fluid...at least pull it and check it's operation as bcschief suggests...I've done that in an old deep pan on the stove with tongs and a thermometer. Easy to change now if needed/desired...Good Luck!
 
How do you know the coolant temperature? My 64 & 65 cars just have arbitrary marks on the dash gage, and I recall that in my 69 Dart. Regardless, use another measurement to verify. I use an IR gun which always compares well with the the dash gage in my M-B's (have numerical marks). I use a 195 F T-stat in my Mopars for better mileage and less engine wear, but many opinions on that.

Twice I changed T-stats and that did fix a problem. My 96 Voyager was showing too cool on the dash gage in the winter, and increased w/ cardboard in front of the radiator. I found the factory T-stat in pieces w/ spring tower off (many cheap ones today). My 1984 M-B was showing 60 C on the dash whereas 80 C is normal, and IR gun also showed 59 C by sensor. Tested T-stat in hot water and it seemed to open & close normally, and looked fine. Repeated against a new T-stat and some Mopar ones, w/ thermometer and IR gun. The IR gun could read the T-stat under water and agreed well w/ the water temperature. I found the suspect T-stat opened too early and had a sluggish response w/ temperature. Installed the new one and dash gage then showed 82 C. Probably improved the mileage. I thought that was a clever test, so posted on a M-B site and one guy said "of course one always changes the T-stat if any question about your coolant system". A bunch of nancy boys there who never work on their own car. You guys are more resourceful.
 
"How do you know the coolant temperature? My 64 & 65 cars just have arbitrary marks on the dash gage, and I recall that in my 69 Dart. Regardless, use another measurement to verify. I use an IR gun which always compares well with the the dash gage in my M-B's (have numerical marks."


I have the factory and aftermarket temp gauge with numbers....
 
I did notice lately that it may not be opening up to drop the temp like it used to. I never goes over 195/200 but usually the t-stat (180) will open up and drop to 180 regularly but not so lately. Maybe I just didn't pay attention to it before since it wasn't on the maintenance list.
Could be a clogged up radiator or a comprsssion leak. Change the t'stat since that is easy.
 
Well I tested the coolant with a candy therometer after she idled for 10 minutes and she was running @178. My factory gauge read 180 but my AutoLite gauge read 190. Guess the ole' 48 year gauge with no numbers is more accurate then the 7 year old name brand gauge, go figure huh. I put it better accuracy, guess I was wrong.
 
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