I have noticed that if I run @75mph or pull my camper my coolant level drops some. I can run @70 or less unloaded and my coolant level does not change. I have a 05 with 140k, run a coolant filter, untuned, had the egr and oil coolers changed at 94k just before the warranty ran out and then installed the coolant filter. My temps are running about 8-9 degrees apart at that speed. Is this a sign that my heads are lifting?

 

I would start with just checking your degas bottle cap. Mine was only holding <4 psi. New one cost me just over $5 from the local parts store.

 

Do you then have to add coolant, or does it come back to normal on it's own? What are your temps when running at that speed/load? My coolant level varies up and down a bit, but I never add anything, and it averages out OK.

Brian

 

Stealth, did you see evidence of puking, I see none but one thing I have always learned is to start with the inexpensive easy fixes first, thanks.

 

Brian I have actually seen it move down and come back up before on the next ride. My temps are usually around 192/200 for coolant and oil at 70 unloaded I think. I will be keeping an eye on it, may pull the camper next month, thanks.

 

Mine does this dissappering act as well, one day it is at the new min line, the next day it looks a half gallon low, but if I add any it pukes it out, till it is right, I just added some the other day against my better judgement, I am betting my next drive she chooches it back out.

 

I did just change my coolant filter and then I added coolant before I drove 800 miles, maybe there was still some air in the system after that and it burped some more.

 

most trucks seem pretty happy about a 1/2" below min line

 

^ Very true! Mine does

 

That is where I am at now, it is within the min/max lines on the little label that is stuck on there. I am going to leave it alone and see what it does. Thanks.