Blowing Bubbles

[87cr250r]

Long story, I bought a 2001 C3500 6.5 engine off eBay. It was supposed to be a runner but I decided to reseal it regardless. Good news is that a teardown revealed it to be a 2004 GEP engine. Bad news the block has 0.010 of wear from the head gaskets. I had the heads gone through and the block resurfaced. I'm not super happy with the work done on the heads. The engine has always blown bubbles since. I got one head off today and found no issues with the head gasket but did find a crack in the head. Not super happy with the staking of the precups. I won't say more. I am interested in options, not my own prejudices

 

[gringeltaube]

I'm not super happy with the work done on the heads...

Reason enough...
1) Obviously the heads were ground with the cups still in place!
2) They should have seen that crack and pressure tested, at least!

Cyl 2 also shows some suspicious spots. Maybe take a closer look to the areas encircled...

 

[87cr250r]

That head had 3 cracks pinned between the valves. That's likely what you see.

I got the driver side head off today. It was clearly the leaker. I used a Cometic MLS gasket because the two 6.2/6.5 engines I have opened all had damaged top decks from vibrating fire rings. Anyways, I seems like the gasket was too tight around the dowel pin and this kept it from seating correctly. Oh well, Fel-Pro +.010 going in this time around.

The driver's side head looks much better otherwise. Less cracking in the pre cups, only one pin, no recessed cups. I bought one bare NOS head on eBay today so I'll swap over the valves and such from the pax side head.

Anybody got any tips for tightening the driver's side rear head bolt in CUCV chassis? I've done it before but it's a PITA.

 

[adf5565]

Were the heads of the 2004 GEP vintage as well? I'm surprised you found cracks in the heads, I thought they had resolved the cracking problems by then.

 

[87cr250r]

I think these heads are expected to crack. They're relieved between the valves so they crack in that region where it doesn't do any harm. I see this on large turbochargers. It's called stress relief cracking.

I really like the idea of MLS gaskets. Quadstar Tubing claims to have a new version for this year. I'm going to give them another shot. I really do think it was that dowel that held things up.

 

[adf5565]

I saw those as well, I hope they work better

 

[87cr250r]

I have received the newest generation of MLS gaskets. They have embossing around every coolant passage and bolt hole.

I also used ARP studs but I'm not sold on the advantages vs TTY bolts.

 

[2INSANE]

Save money, live better and watch you tube videos. Yes this repair works. Less then $20 and some elbow grease will fix those cracks!

 

[adf5565]

Did you have success with the repair? How did the MLS gaskets work?

 

[87cr250r]

It still has bubbles. The head shop pinned the cracks between the valves but in one location they did not install the pin under the valve seat. It's outside of the combustion chamber, it only sees exhaust pressure. The engine runs perfectly otherwise and consumes no coolant so I'm just going to watch it for now