I observed a small amount of air bubbles coming out of the hose in the coolant recovery tank when the engine is up to operating temp. and I've had to top the tank off in the past couple days. Engine runs great and idles fine. Checked out the oil and no milkshake yet. However, I noticed some moisture buildup under the oil cap. Does this sound like a blown HG? Haven't done a compression check yet. Hopefully it's not a cracked head. <img src="/forums/images/graemlins/frown.gif" alt="" /> On a positive note, now would be the time to consider upgrading the cam. <img src="/forums/images/graemlins/lol.gif" alt="" />

Have you ran the engine without the radiator cap on? My truck was running fine with a blown HG, and the first clue for me was a round of broken hoses and heater core. I ran it without the radiator cap, and bubbles kept coming up through the radiator. It was also losing a small amount of coolant over time. Here is the source of failure on mine:



The metal part of the headgasket stretched then split right near a coolant passage, allowing the coolant system to be pressurized from the cylinder.

It sucked, but it also was definitely the right time to upgrade the cam! <img src="/forums/images/graemlins/smile.gif" alt="" />

Hopefully it's not the case with yours, have you replaced any hoses, water pump, etc. lately? Maybe you just have some air that needs to be purged from the system. You can do the park-on-a-hill-and-run-it-without-the-cap-test to purge the system of air. If you run it for a long time, and the bubbles don't stop, I would suspect headgasket.

when mine went, i got pretty lucky. the #4 fire ring deformed and cracked ever so slightly between the #3 and #4 cylinders. no coolant into the oil, but it did turn my overflow reservoir into a brown fountain...