Now I am confused (headgaskets?)
I went camping over Memorial Day from the Springs to Mesa Verde. Pretty good climbs over La Veta Pass (6%) and Wolf Creek Pass (7-8%) towing a 12k 5th wheel. I was puking coolant and getting hot, but I took it slow and made it to Mesa Verde. I had lost about 2 quarts of coolant (I have the new sticker on the bottle and even keep it a 1/4 inch or so below the revised line).
One the way home via the same passes, I had some more high temp pulls up the passes and I am sure it puked a little bit. Then on I-25 coming north out of Pueblo temps in the mid 80s, I was going up another another long but less steep grade. It was hot and I was running 70 MPH or so. My ECT was running up to 220 and the fan would come on, and things would settle back down. However, on one long grade, the ECT kept rising and rising and eventually hit almost 240 when I crested the hill and coasted down the other side. Things cooled off pretty quick and I continued at a slower speed. Coolant pressure was definitely on the too high side (16+ psi). By time I got home I had lost about 2 quarts of coolant.
Now I am thinking that what I had previously assumed was bad head gaskets (I had a mild puking incident in going to Moab last year) had gotten worse and the exhaust in the coolant was making the engine's cooling performance suffer hence the higher ECTs. However, today I used a BlokChek kit (the one where you pull gasses from the coolant bottle through a tester and see if the blue fluid turns yellow or green), and low and behold there was NO color change.
What gives? Is is that the gaskets are just not leaking until they are under a heavy load? Even when I drive unloaded, the coolant pressure eventually creeps up to 15 psi or more. The cooling system is always under pressure, even when stone cold (about 4 psi or so), so I assume that the residual pressure is from the gases that entered the system through the head gaskets. When I start driving with a cold engine and really hammer on it the pressure gauge does not jump up really fast like I have seen on youtube. The pressure only builds fairly slowly and once the coolant is hot is when the pressure will be up around 15 psi or more.
I have a recent oil cooler rebuild (delta runs 4 to 6 even when towing) and a BPD EGR cooler (as well as SCT tuner running tow tune - EGR valve should be shut off). 2005 CCLB 4x4, approx 114k miles.
I am almost certain it is head gaskets, but this BlokChek test has me confused. Opinions?