Temp Fluctuation
 

Man this has been driving me crazy for about a year now. My temps swing from about 180-215 depending load. It will get up to 215 on hard acceleration with no load. It always cools back down. Never overheats. Cleaned radiator, flushed coolant, dealer replaced water pump about a year ago because it was leaking, and maybe this water pump isnt as strong? Never tried replacing thermostat. Could the head gasket be leaking? This morning after a trip to the lake sitting in the driveway the temp stayed at 210 for awhile, turned the AC on and it cooled down quick to 180..??? What gives?

No ones ever experienced this?

Thanks, I'll post it on TDR.....

I'd check to see if the fan clutch is having problems, it might not be engaging properly. This may expalin your temp issues. Other than that you may have a temp sensor issue (less likely).

Hey Franklin ->Respectively - you gotta give us some time.... Sometimes the guys with the answers for a particular problem are not looking right away when you post.....


Your last comment really points towards the cooling fan. Does it consistently cool it off when you turn on the A/C or did that just happen once? Do you have a viscus fan clutch or is it electric? If it's electric, then it seems like the engine temp sensor is not turning the fan clutch on.

When the A/C kicked on the electric fan clutch was engaged, that's what cooled it down. I had this issue and it was due to an air pocket. Pull the radiator cap when the engine is cold and check the coolant. If you are low, you may have an air pocket or a leak. Is your truck sucking in coolant from the overlfow tank? If not then you have an air pocket.

Ive had these issues for ever. Mine was so bad I installed my own coolant bypass system. I hate that it constantly gets so hot above 215 all the time. I have a temp guage separate from stock.

It is very possible that you have air trapped in the engine. Remove the allen plug in the top of the head close to the thermostat. If coolant comes out you are OK. If there is air then fill the radiator until coolant comes out. Put the plug back in and finish filling the radiator.

I know from experience that as much as a gallon of air can be trapped in the engine and the proceedure above is one of the sure ways to make sure you get it out.

I have the same problem, have the temp going up and down 180 to 210 even in the cold.
I'm thinking it is the Fan clutch, was reading that it should kick on at start ups even cold, mine does not. I remember it doing it in the past.
Have changed everything else been doing this for 6 months or more, don't want to tow with it. No codes...
You would think if it is the fan clutch it would blow a code....
But none.
It is getting old.. At 130k and all the little things are starting to get you 100-200$ at a time.... Plus the down time.

You have an air pocket. Pull the radiator cap when cold and if the fluid is not all the way up to the top, this is your issue.

Thanks Papa Duck for the contribution. I was experiencing a higher than normal temp reading while towing a load with the a/c on which is usually not a problem. But when I hit a hill, the temp would rise to 3/4 and then race to the redline after a minute or two. I did as you suggested that evening and lo and behold, there was an air pocket under the plug!

I had the same exact symptoms a few years ago and it was the thermostat. I changed it and problem solved.