Considering this history, it would be interesting for the thread to get pictures of the gaskets and heads to see the pattern, or not. And how much the head is deviated from flat.
Take a picture of the antifreeze level in the degas bottle when the engine is cold and post it.If you mean belched by bled off the pressure then yes after it belched the pressure was at 17psi. Under normal driving unloaded conditions I only see about 6psi. The degas bottle is maintaining under normal driving conditions. By maintaining I mean it stays within the max and min level and checked regularly.
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Yes sir, I agree that the factory min should be max. There is some debate about that. I always run mine about 1/4" below the stamped min and have found that when pressured up the degas bottle never goes empty and that's what is important. As for the pressure after warm up test, I did that about 6 weeks or so ago and built up about 1.5 psi after warm bleed off.The max level is TOO high for our trucks. The MIN line should be the max you fill the bottle to. Even 1/2" below the minimum line
What I meant about bleeding the pressure off is: get it up to operating temp, then open the cap by hand, carefully, to get the psi to 0, then drive it and monitor what it goes up to
I would implore you to still do that. With the experience others here have with failed gaskets and looking at pressures, that could be a clue there....... I almost thought of just stopping and releasing some pressure when needed. Then continue driving the truck in its present condition. ......
Hey man, I'm appreciative of the help and suggestions. I'm not sure what else you want to see. I'm glad to do all the diag possible on my truck. I think I've done everything that's been suggested except for bleed pressure and watch for a further build while towing. Towing hard is the only time I see this type of pressure as others have stated. I'll have the 5er out again in about a week and I'll do the bleed rebuild process then. I don't want to spend the money to restud my truck but time wise I'm in a spot to get it down now, I've got another vehicle to use until mid Sept. after that I use it everyday. I think TooManyToys posted a good link with a very plausible theory and I may pursue that ave.There are specific reasons we ask you to do the tests, and the order of them. I'm not convinced you have a head gasket problem. But, it's your money if you want to have your guy tear it apart.
Ok, here are the results you were asking for. After the first 25 min. it was at 12 psi. I bled it down to 4 psi because that is when it started to loose coolant. I drove for the next 20 min and the end result was 17 psi. The total trip time was approx. 45 min.Replicate the problem, then bleed off psi. Then replicate what you did to begin with. If your psi goes back up to 16, then your gaskets are bad. If the psi doesn't go back up, they're ok.
Just because it goes to 16 initially doesn't mean they are bad. Just that there is enough thermal expansion to reach that pressure. That could just mean you are over filled with coolant and the air is compressed in the degas bottle. Once you relieve the pressure, then you can tell if the gaskets are leaking pressure into the coolant system. Without relieving the psi, your not able to verify that. You need to get the coolant up to temp so the thermal expansion is out of the equation. Only then can you tell if your gaskets are bad