Now What The Heck.

[simon]

I am in the process of rebuilding a 95 929 block,got it out of my trashed truck[see sig] decided to check bearings before bolting it over in other truck. engine was running strong and not using oil or anti freeze.well after finding flaking brgs,figgered may as wel strip it down and fresh it up. took heads in for seatgrind[ofcourse where cracks between the valves,not big deal,figgered on sleeving them anyway]but machine shop says cracks all over in the valve area.

OK I got other set on the shelf,meant for powerup project. Nice clean 99 heads, NO cracks between valves or in the precups.take them to same machineshop for seat grind.
Fellow phones to tell me these heads are cracked worse than the first set. I can't believe it. I will go there tomorrow to see for myself

Whadda you think,seen that before? or is he pulling a fast one

[arveetek]

On my '82 buildup, I went through 3 sets of heads before the machine shop agreed to machine them. The first two had enough wear and cracks that they didn't want to work with them.

Your shop may be looking for perfect heads, which don't exist in all honesty. I'd go to the shop and see where the cracks are at.

Casey

[JetBoater]

I had a set of heads repaired for $900. The machine shop installed Mac Truck hardened valve seats... machined deep into the head which gets rid of the surface cracks.
They did the water jacket fix as well which stops the cracks from developing from the top.
If you go with new heads... they will eventually crack too. I would consider fixing what you have if they can be repaired.
Good luck.;)

[simon]

I went to the machineshop yesterday and had a look at the cracks in the heads. well they are every where, extending out trough the exh valve seats about 1/4". funny thing is there are no cracks between the valves. its gonna be to costly to put seats in all of them,and the cracks will still be outside of the seats.

Sooo''' I"ll have to use my last pair,Brandspanking new CHINESE ones.

[More Power]

This web site was started more than 12 years ago because of cylinder head cracks. During a rebuild in the fall of 1995, I and others inspected about 150 6.2L cylinder heads trying to locate a crack-free set that had the same casting number. I was unsuccessful. My truck, which I depended on, was kept off the road for several weeks because of the delay in locating a set of decent heads. At the time, new factory bare heads were about $800 each, and were just too expensive - though I was considering them.

As a result, the crack repair procedure discussed here was one of the very first tech pages that appeared in The Diesel Page.

Since then, I have seen quite a few used factory GM 6.2/6.5 heads that were 100% crack-free. For example, our project 6.5 was assembled with used but 100% crack-free cylinder heads.

I've only seen a couple of heads that had cracks in areas other than between the valves (the repairable kind).

Jim

[simon]

This web site was started more than 12 years ago because of cylinder head cracks. During a rebuild in the fall of 1995, I and others inspected about 150 6.2L cylinder heads trying to locate a crack-free set that had the same casting number. I was unsuccessful. My truck, which I depended on, was kept off the road for several weeks because of the delay in locating a set of decent heads. At the time, new factory bare heads were about $800 each, and were just too expensive - though I was considering them.

As a result, the crack repair procedure discussed here was one of the very first tech pages that appeared in The Diesel Page.

Since then, I have seen quite a few used factory GM 6.2/6.5 heads that were 100% crack-free. For example, our project 6.5 was assembled with used but 100% crack-free cylinder heads.

I've only seen a couple of heads that had cracks in areas other than between the valves (the repairable kind).

Jim
well Jim,i had 2 heads out of an overheated 6.5 that had cracks from a valve al across to the lifter gallery. 4 more heads from otherwise good running engines with valve area cracks,but the 99 heads did not have cracks between the valves.
So what causes these to fail , 2 where 98, 2- 95,and 2-99's, high EGT's ??

Would you chance using them even with seat inserts