So I made it to Crested Butte today.
I'm having a very hard time making sense of my problems. The problem appears to be gone now.
Here's the set of conditions that led up to my water temps hitting 200 degrees on I70 in Missouri and making me think I blew the head gasket again:
In the photo above you can see that I had installed a radiator screen to block the flow or cold air through the radiator. I was using Napa premixed 50/50 HOAT heavy duty diesel coolant. It's the stuff that Cat (or Cummins) recommends. I do not have the stock radiator overflow tank installed. I have an aftermarket unit that might be smaller in capacity. I was running a 13lb lever-vent radiator cap.
After about 3 straight hours of cruising at 70mph through Illinois I noticed the temp gauge started climbing above 185. It was 40 degrees outside and I had the radiator blocked still. I checked the coolant level and I was about 1 gallon low and refilled with the same Napa brand and type of coolant already in the engine. I started getting concerned that maybe I didn't have enough airflow through the radiator so I cut a 3 inch by 10 inch hole in the radiator screen.
100 miles later I needed another 3/4 gallons of coolant. Still pushing the truck fairly hard at 70mph most of the time. Pyrometer was running 950 to 975 degrees F. Engine water temps would get up to 185 on long hills but drop back down to 175 which is normal for the mechanical Autometer gauge in the truck. Never blew the cap and did not notice a mess from the overflow tank. Still running the 13lb cap.
I forget how far I went to the next stop but it needed coolant again. The truck stop did not have the same type of coolant I was using. So I ended up buying some of the green stuff that was labeled "compatible with all antifreeze types". It took about 3/4 of a gallon. Within 15 miles of putting this stuff in the engine temps got up to 195 so I pulled over on the side of I70. I used the radiator cap lever to vent the pressure and couldn't believe the pressure I released. I thought for sure the head gasket had blown completely. I pulled the cap and a lot of thick foam shot out under pressure. I could see no liquid, just foam. I poured a little over 2 gallons of straight water in after it calmed down a little.
Every 50 miles or so I would stop and check things. Each time there was foam in the top radiator tank I would fill with water and flush as much foam out as I could. With each stop the foam situation improved but I was still losing coolant. That's when I decided to call it quits in Concordia and assumed I had a blown head gasket.
The next morning I 25 miles or so from Concordia to Higginsville and stopped in at the local parts store. I bought some more antifreeze (green type) and a 16 pound radiator cap. I adjusted the wastegate to make sure the turbo was essentially disabled. I adjusted the injection pump screw in one full turn.
Then I drove back and forth from Higginsville to I70 twice and checked the coolant. A slight amount of foam but I didn't lose any coolant. This was encouraging so my wife convinced me to attempt to press on towards Colorado.
I would stop and check the coolant every 40 to 60 miles across Kansas. I flushed some foam out a few times but it never really needed much coolant added. Only a few cups at most. I noticed the engine temps climbing up to 190 at one point so I cut out the remaining portion of the radiator screen. For the last 150 miles before stopping in Limon, CO for the night the truck needed no coolant at all.
Today I drove from Limon, CO to Crested Butte, CO. It's about 300 miles with some serious changes in elevation. I adjusted the wastegate so I would get about 5 psi out of the turbo expecting that I would start losing coolant. That never happened. 300 miles with the turbo working and no loss of coolant. It actually ran very well and I pushed it pretty hard. 12,000+ foot Monarch pass was a slow, 2nd gear affair but that's to be expected.
So now I have to figure this all out. Did I just have a bad radiator cap? Will mismatched antifreeze types foam up horribly?
I plan to flush the cooling system tomorrow, refill, turn the boost back up to 9 psi and drive the thing back and forth to Gunnison. Then test for exhaust in the coolant. I figure that's the best course of action before assuming I have a bad head gasket.
Is there a problem running a 16lb cap instead of the stock 13lb?
What would happen if my aftermarket overflow tank is smaller capacity than the stock unit? How much will the stock overflow tank hold? I think the aftermarket one is only 28 ounces.
