last week I changed the intake gasket on my father in laws 99 olds bravada (4.3 L Vortec) after a day or so we had an overheat problem, took off rad cap, added fluid problem solved. yesterday had another overheat problem and intermitent heat/no heat. when changing intake replaced t-stat. yesterday filled cooling system and put on a new rad cap. filled system, started motor (with cap off) let it run, little fluid came out, topped off system and resivior after t-stat opened. i then drove aroud for 1/2 hour, good heat and temp just below 210. 2 hours later did the same thing (driving) and no problems. This morning my father in law took off the cap to check the fluid and had to add a little to top off. (coolant in res was good) went down the road and within two miles had an overheat situation (almost 260). NEED HELP!!!!! any sugestions. could it be a bad new thermostat?? any advice would be appreciated. Thanks in advance.

 

What's up 98SmokeBlazer -

I kind of had/having the same problem as you... I had an overheating issue last summer,I did the same thing added fluid and it never happend again... BUT now I have a problem where my engine is not heating up enough... Normally it stays right under 210 but mine is way below that! There is a code for it which is P0128 "Coolant Thermostat Coolant Temp Below Thermostat Regulating Temperature" I think my thermostat is sticking open ... I need to get this taken care of asap for emissions... my car only overheated that one time and it never did that again, maybe that time the thermostat was sticking closed??

 

Wayne, is the engine throwing any codes during this process? If, so, what are they? If you believe you might have air in the system, raise the front end of the truck with the passenger side higher than the driver's and let the coolant circulate to burp the air out. And yes, you might have a bad thermostat.

Bridget, it sounds like you have a bad thermostat (failed in the open position). Has your gas mileage dropped down? If it has, your engine is staying in the open loop cycle and would cause a loss of power, mileage, and will probably fail emission testing.

 

riddle thereare no codes being thrown. but i will replace the t-stat and raise the pass side. thanks for the help.

 

Anytime you overheat you must replace the thermostat.
It has a wax heat sensor, once it over heats you must replace it, wax won't reform to its original form once melted.

This time do step three once you replace the thermostat.
Always run the engine up to normal operating temp and crank the heat on full blast. Once you think you go tit full, put thte rad cap back on and take it for a 20 minute drive. Park it and eat dinner, let it cool for an hour ofr so. Take the rad cap off slowely, crank the engine up and blast the heat. Top off.

 

did the t-stat on sunday everything was fine until today. overheat, low coolant, and lower rad hose collapsed. any sugestions now? thank in advanced. Wayne.

 

Check your engine oil level to see if it went there. Auto or standard tranny?

 

Have you re-torqued the intake manifold bolts since you did the job?? I was told after a little less the a week to check the bolts and re-torque them down its what I did!!!

 

Thanks for the sugestions guys. Oil Looks good, no coolant, it has an auto tranny, and I will recheck torque to eliminate that possibility. I will let you know. Thanks again.