I had to put a new radiator in my truck old one sprung a leak. It has a new thermostat in it the coolent is full but it always runs below the normal range. Im really confused please dont tell me its a thermostat if it is the thermostat im just taking the piece of junk out. Thanks jeff

mudslut79 said:

I had to put a new radiator in my truck old one sprung a leak. It has a new thermostat in it the coolent is full but it always runs below the normal range. Im really confused please dont tell me its a thermostat if it is the thermostat im just taking the piece of junk out. Thanks jeff

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How 'bout some more info...what truck are we talking about? How much below the "normal" range? And where did the needle used to sit before you did the work.

Its a 97 ford ranger with the 4.0 automatic it used to sit halfway now it sits right below the normal range.

I guess its not that important to have heat thanks for the help though.

MY 4 liter sat there as well my prob was exactly that a stuck open t stat. beter open than stuck closed tho. not for the heat of course

mudslut79 said:

I guess its not that important to have heat thanks for the help though.

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Patience is a virtue...


"Not have heat", though? I get heat (some, not full) in my Ranger starting about when the needle moves off the "C"...well before it gets to normal, let alone mid-scale. By your description of where the gauge is sitting, I'd think you'd at least have some heat.


At any rate, the thermostat does sound like your most likely culprit. Just "taking the piece of junk out" will mean you REALLY won't have any heat, though...depending on how much time versus how much money you want to invest, you can take it out and test it in a pan of water with a cooking thermometer to verify that it opens/closes at the correct temperature (sorry, don't have the number off the top of my head*). Or you can buy another new one, and put it in. (Or, if you have the one you took out, you could put IT back in, too, I guess.)

I guess it's possible that there's some other problem, that may have been pre-existing (i.e. sticking fan clutch), but I'd say it's probably the t-stat.


*A very quick online search leads me to believe that you should probably have a 195* t-stat in that truck, but I'm not positive on that.

Yeah im not really sure whats going on it seems like i already had 10 different thermostats in they all seemed to be junk. Im just out of patients with the whole thermostate deal as i think anyone in my position would be. Is it possible that it could have air bubbles in the coolent that havent popped yet?. When i filled it i didnt have the motor running im thinking about draining it and putting the coolent back in with the truck running and see what happens.

Turn on the heater, pop the radiator cap off, and let it idle for 20 minutes. No need to drain/refill if you're worried about air pockets.

*Where are you getting your thermostats, and how are you verifying that they're the correct part? I'm wondering if someone is selling you a lower-temperature thermostat than your truck should have- 180* instead of 195*, for instance. Wish I could say for certain what the right temp is, but I don't know and don't have any resources I trust floating around here...

most vehicles stock have t-stats ranging from 180-198 (depending on the make model ect ect...) 195 sounds normal for the majority of vehicles out there...

there are some t-stats floating around out there that open at 160... but most people that get those are the racers wanting to keep their engine temps down so theyll run cooler..

but id have to agree with ian there.. sounds like someone may have given you one to run cooler.. that or its failed in the open position... i had one go on me in just under 500 miles that was brand new... forced me to do a top end rebuild on an engine id just finished putting back together... went with the cheap brand one.. will never do that again... now all i run are fail-safe t-stats..

I am fighting this problem right now - I dont know what normal is for my 94 Ranger because I dont think the gauge has worked since I got it ....Now I flushed radiator (it was full of Bars stop) and changed thermostat to a 195 - the gauge moves now but only from the line below the c to the first line right at Normal ..never goes any higher - I have MEGA head coming from the heater...itll run u out the truck ....Using thermal gun on it now to try and figure this out. I will post when I have a result or another question lol