6.2 and 6.5 heads

[Kevmcgill]

Hello all- I did a search for the title of this thread and couldn't find anything. Here's my situation, I have a 91 K3500 dually with a 6.2. It has "bubbles" in the radiator. My guess is a blown gasket and/or cracked head. Is this a correct assumption? Or is there something simple I am missing?
Second question, are 6.2 and 6.5 heads interchangeable? I've heard conflicting opinions from the chevy dealer, and a guy on Craigslist with 6.5 heads for sale.
Any thoughts and advice are greatly appreciated.
Kevin

 

[just a number]

yeah,I'm sorry to say your guess is correct. IIRC the heads should be interchangeable. any mixing of the oil/coolant? or just the bubbles.

 

[buddy]

heads are interchangeable, a little more fuel use and power from 6.5 heads with larger pre-cups.

 

[Kevmcgill]

I'll take bubbles in my hot tub only please ...

yeah,I'm sorry to say your guess is correct. IIRC the heads should be interchangeable. any mixing of the oil/coolant? or just the bubbles.

Just bubbles. I'm hoping I caught it before any damage to the heads so I can recoup the money I paid for some reman'd off Craigslist. I took off the left side today and it actually looks OK. the right will come off tomorrow. wish me luck.
Kevin

 

[just a number]

Missy good wrench(MGW) had a good post over in the 6.5 section on finding main web cracks. It may work to check the head too. the metal ring in the gasket is the leak area. how old was the head gasket in there?

 

[Kevmcgill]

age of gasket unknown. I am 3rd owner. To my untrained eye they looked in good condition. Didn't see any clear signs of blow by.
K

 

[just a number]

you probably won't. did them come off nicely or stay stuck on one side? One more thing to remember doing head. the head bolt are one shot deals. they're called yield to torque. they stretch when installed.

 

[Kevmcgill]

Copy that. The gasket came off fairly easy, except in one place. It was sort stuck on and ripped when I pulled on it.

 

[Kevmcgill]

Piston damage from glow plug

I'm waiting for bolts and exhaust gaskets and while I was cleaning gunk out of the cylinders I found this. A glow plug in another cylinder was also broken but I couldn't see any damage to that piston. It looks like it bounced around in there a few dozen times before it got ejected.
K
PS thanks for all the welcome notes.

 

[Acesneights1]

Check the Cylinder very carefully for hairline cracks. That could be where your bubbles are coming from. I had an air cleaner stud end up in there and it cracked the block. As far as the heads go if unsure send them to a machine shop and have them checked. It would suck to do th whole job over to save a few bucks if you missed something.

 

[D.Camilleri]

Most common cracks are between valves and don't lead to combustion leaks. If the engine was allowed to get real hot, check heads carefully for other cracks. Usually they are easy to see. 6.2 and 6.5 heads are interchangeable with some minor changes. 6.5 heads have a different angle that the injector sits at and requires tweaking or replacing the injection lines. Late model 6,5 van and hummer heads have different bosses drilled for the intake manifold bolts. There are lots of variations of valve sizes and precup sizes, biggest thing is to make sure both heads are the same.