I can let my 96 4.3 4x4 blazer warm up for 15 minutes and the temp guage will only get barely over 100 degrees. i can drive it all the way to work and the inside will never get very warm. does anyone know why the engine is warming up very high?

 

Probably time to change the thermostat.

 

I have the same problem... Will it hurt anything to let it go like this?

 

It'll hurt your pocket book as the truck will never get out of open loop operation (i.e. guzzle gas). It really is quite easy to replace the thermostat. And it is cheap too! While you're at it, get a new radiator cap (Stant safety cap).

 

I had the same problem on my 97. finally fixed it, took about 10 minutes & $7

 

So I'm killing my mileage because the truck isnt getting warm? Wow, Id love to squeeze some more mpgs out of the old beast. I already get 20 on the highway @ just above 100* on the t-stat... Operating temp should be at 195* right?

 

Not to go offtopic from the original post, but if you are getting that kind of mileage, then I would suspect a faulty temp gauge sending unit. But then again, I do not know what you are driving.

The OP had stated that he has no heat and that it doens't come up to temperature which the two combined would first lead me to a faulty t-stat. And yes, if the t-stat is stuck open, it would lead the PCM to be stuck in open loop mode for any '96+ vehicle. Older vehicles may not be hindered by this.

 

I have the same symptoms... no heat for a reallylong time and low temps ALWAYS. I have a '89 4.3 if that makes a difference...

 

I'll try to answer all three at once.

There are two tempature sensors, one for the gage in the dash and the other for the puter. It is possible for one to fail and not the other.

If the temp gage isn't going up and you dont have heat, your thermostat is stuck open. Replacement is the only way to fix it, and a new one is like $10 plus anti-freeze and distilled water. out the door for under $25.

If your truck has a 4L60E tranny, then yes you can cause some major damage. The short version is you can fry your tranny. The puter uses the tranny heat to get the engine up to operating temp, if it never reaches operating temp, the puter never locks up your torque converter, not only are you los mpg, but your also frying your tranny. Heat is the #1 reason tranny's fail.

 

I have a 96 blazer that only heats up to 100 degrees also. I have been having tranny issues. It slips in and out of overdrive and shifts sluggishly. Could the low temp be the cause?