Temperature Variations 160-195

[Greg]

So I just put in a new thermostat, thinking this would fix my problem. No dice.
Filled up on coolant to make sure everything would work. No dice.

My problem is when I start up and start running down the road, the temp will climb up to 195 like it should, and then it drops back down to 160, (where it would sit constantly before I put the new tstat in) and sit there for a little bit, climb back up to 195, and then drop back down to 160, and repeat the process over and over. WTF is the issue?

My dad thought it could possibly be the intake gasket (which we replaced around 125k).
This is irritating me. Has anyone else had this issue? If so, what did you do or find out to fix the problem?

 

[Butch]

When was the last time you completely flushed the coolant?

 

[barebones 1500]

sounds like it might be air bubbles in the coolant. try doing a flush like Butch said. and if you are fine with a possible cheap fix, try running a bottle of stop leak in there to seal up a possible bad head gasket. normally the stop leak does not work but for 5 bucks, it is worth a shot.

 

[bggrnchvy]

Is rad cap holding pressure?

 

[jcro61]

Is rad cap holding pressure?

I second that. The loss of pressure will result in temperature changes of the liquid

 

[Greg]

When was the last time you completely flushed the coolant?

sounds like it might be air bubbles in the coolant. try doing a flush like Butch said. and if you are fine with a possible cheap fix, try running a bottle of stop leak in there to seal up a possible bad head gasket. normally the stop leak does not work but for 5 bucks, it is worth a shot.

I've never flushed the coolant, and to be honest, not sure how.

With the head gasket, don't you lose power as well? I've still got plenty of power, even though I know and can feel my tranny getting weaker.

Is rad cap holding pressure?

I second that. The loss of pressure will result in temperature changes of the liquid

How do I know if the rad cap is holding pressure? And the changes in temp aren't permanent, they swing up and down constantly.

 

[jcro61]

If you had a bad head gasket you would be either burning coolant, have coolant in your oil, overheating or any combination of the three.


You can get a pressure tester to test the cap. I don't know how to test otherwise. I have a tester so I have only used that.


As for the fluctuation of the temp, does it do it when you rev or does the engine rpm have no effect on it? If it cools down when you rev it, it might be low on coolant, maybe a small leak.

 

[Greg]

engine rpm has no effect. I put it on cruise at 70 mph down the highway, and the temp was jumping around on its own. It is full on coolant. I just topped it off when I changed the tstat

 

[bggrnchvy]

If the cap is releasing at a lower than marked pressure you would get constantly swinging temperature. The pressure would build and release, build and release. The temp would change as a result.

I'd just pick up a new cap, they're all of $6.

 

[jcro61]

I would change the cap and go from there.

For anyone who is interested this is the type of tester I have, I have a different brand tho.
http://www.google.com/products/cata...og_result&ct=result&resnum=1&ved=0CEcQ8wIwAA#