head or headgasket issue?

mustang_gt_350 · **Joined:** Tue Jun 01, 2010 8:47 am **Posts:** 191

I have been loosing a very slight amount of coolant for the last 2 years. About every 2-3 months i would have to add then i would be good until i would get the low coolant alarm and do it all over again. This time I don't remember for sure but i beleive it to be alot closer in time frame. I ended up adding a fair amount. I'm guessing a little over a quart. I drove it for 25-30 miles and shut if off at work and hurt a gurgle. So i checked the level and it was fine. Drove it home and in the morning popped the cap to bleed the pressure since it was hot, and placed the cap back onto the bottle for about 10 seconds or so and it opened it again and heard it release pressure again. I also noticed this at the same time as doing the cap bleeds. The level did not seam to drop as the bubbles were pushing out. I'm guessing its the headgasket since the level never dropped. I'm letting it warm up again so i can see if its still pushing air. I removed the cap, and started it cold, placed the cap back on for a little while 30 seconds or so and removed it and saw a tiny amount of bubbles from the hose that attatches to the bottom of the tank almost directly under the cap. However it wasn't any major noise when i opened the cap, just a few bubbles.

I'm guessing its leaking just enough to push pressure into the system, then back drain it into the engine with the pressure thats held after shutoff. And that is where my loss is going.

https://www.youtube.com/watch?v=jlsZp7sU_LA

Mountainman · **Posted:** Wed Apr 06, 2016 11:13 am

Sure sounds like HG. Run it at a cold idle and shine a bright light in the reservoir (cap off), and you'll probably see lots of tiny bubbles streaming out.

mustang_gt_350 · **Joined:** Tue Jun 01, 2010 8:47 am **Posts:** 191

I started it and let it get up to temp after i made my first post. I released the pressure and The whole time it was at idle with the cap off at temp i had bubbles coming out of the small hose. I do have one of the higher temp thermostats in one of those inline hose housings. But i can't think of anyway that it could be causing air to be in the system.

About 99% sure its the HG. There is no way with that many bubbles that the coolant level wouldn't have dropped at all while i had it running with the cap off if it had air in the system.

Looks like its going to be tear down time in a few weeks. I don't have time to do it now, so i'll just park it and run the XJ

I will try the cold start with flashlight test when i get a chance. should i be looking down the cap hole, or through the sides? I don't think i can see much through the sides if the bubbles aren't that big.

Mountainman · **Posted:** Thu Apr 07, 2016 2:10 am

Down the cap hole. Dang, looks like time for ARP head studs...

mustang_gt_350 · **Joined:** Tue Jun 01, 2010 8:47 am **Posts:** 191

Looks to be that time anyway. I guess it give me a good chance to check on the cylinder walls and cam/follower condition.

flash7210 · **Posted:** Thu Apr 07, 2016 9:44 am

Have your head pressure tested for cracks.

mustang_gt_350 · **Joined:** Tue Jun 01, 2010 8:47 am **Posts:** 191

Already had that planned. I see no gain of not having it gone over at the shop before spending all that time/money putting it back on to find out its junk.

head or headgasket issue?

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