Cracked head. What do you think about it?

[Rodd]

Thanks Will! I did. Attention to detail is what I lack sometimes. I watched it 3 or 4 times and for some reason I was thinking it was between the cylinders not the valves.

 

[WarWagon]

I would be concerned that the crack may have hurt the valve seat and that may need to be replaced. I suggest some of the China knock off heads would be better than fixing cracked GM stuff. No idea how hard it is to get parts in Moscow.

I have had 3 head cracks hit coolant. The first in the early 90's would blow coolant out of the radiator from overheating when block heater blew out. We only pulled 1 head to fix it after the t-stat housing removed bubble trick. My 1992 project and now Patch:

Here is a cracked head and not visible is the cracked valve seat extending up into the port. #8 of course. Signs of coolant were present.

 

[Husker6.5]

Well clean the area and use some Prussian Blue. The crack will jump right out at you. Unnecessary on my 94's heads, the burnt antifreeze streaks from between the seats on #s 8,6,4 & 5&3 were a dead giveaway (so was going through 8 gallons of mix/straight water in 60 miles!)

 

[Will L.]

Talking to someone about these, He mentioned- I dont think much of machining work, but this might not be a good diy for everyone. This is NOT grab a cordless drill and go process. Very accurate drilling and reaming to proper depth and zero room for wiggle wobbles. Know how doesn’t substitute improper tooling.

And this is really a bandaid, not actually fixing the crack. So for many, just replacing the head is better.

I just don’t want folks at home grabbing a dewalt and going to town.

 

[Husker6.5]

@WarWagon , the CKO heads I bought back in '06 from Alabama Cylinder Head Exchange for my '94 are definitely better that the OEM heads as far as standing up to use and abuse. The CKO heads weighed about 5 lbs more than the OEM and that extra metal was in the area between and around the valve seats. They came loaded with NEW valves, springs, retainers and keys as well as diamond cups. At the time the cost was $285 each plus $60 shipping total for the pair. Some extended on-line sleuthing determined that this was the source of all the other "new non-OEM replacement" 6.2/6.5 heads that pretty much everybody was selling at that time, SSDiesel and various other head suppliers.

 

[WarWagon]

Detail of crack that was leaking coolant. Note valve seat cracked - maybe would burn a valve in the future under a good load. Arrow indicates how far up the port it went.




Rebuilt heads with pipe plugs after procedure done by a shop that just does it because they know what they are doing.




Reference stock freeze plugs: