Hey guys I just bought a 99 blazer 4.3 vorteck i drove it before and everything seemed fine started home I had the heat on then it started to turn cool i looked at temp hand it was past 260 then it would go back to normal then i would have heat again then it would do it again but dont think it was running hot no steam or anything coming from engine. Then i was sitting at red light then hand buried i reved the motor up it went back to normal. Then guy i got it from did say he replaced the t-stat Thinking it could be air dont know for sure. Would anybody have any idea what else it could be Thanks Duane

 

Definitely sounds like there is air in the system. These engines can be a pain to get all of the air out. I have found it easiest to park on a very steep hill with the front end up, passenger side higher than the driver side (to put the cap at the highest point). Remove the cap & bring the engine up to operating temperature. Fill the system and reinstall the cap. Fill the reservoir to the required level and you should be good.

 

Thanks i was kinda figured that was what it was i had a 98 that done something like that but it lost power then it was a head gasket thanks again. I have one more thing the 4x4 light flashes when i engage it. I think it might be vaccum hose some where on it This one has the 2 hi 4 hi 4 lo and auto 4x4 Thanks Duane

 

The 4wd light flashing could be several things. The 4-button NV236 system has a vacuum solenoid on the firewall that controls the actuator under the battery to engage the front axle. You could start there. There is a lot of info in the 4wd related tech articles. Read through all of the tech articles as most of them have been expanded to cover quite a bit more than their original titles would imply.

 

Thanks alot I will look through it all and see if i can figure it out

 

ok guys i put more coolant in my blazer it seemed full also the resvor looked full and it is still doing the same you think is still has air in it