Yep. They crack from clogged cats because of the lack of exhaust flow causing the heads to heat up.

Blamo.

 

I think they crack between the valves or valve seats

 

10-4.

Weak casting to blame. Which is why, unless you're broke, you don't buy reman heads.

 

Ok did a little more investigating. Pulled all the plugs and they look like this:

7,5,3,1 on top and 8,6,4,2 on bottom in that order.

Compression check:
1 - 160
2 - 160
3 - 145
4 - 150
5 - 140
6 - 150
7 - 150
8 - 155

These numbers are down approximately 15 lbs since 1.5 years ago.

I talked to a couple engine builders local and they told me to gather the info I did. Pull the heads and take them in to get magnafluxed for problems. They will check for warpage, burnt valves, bad seals and advise. At that point I can check the cylinders for scalding and damage.

Then the decisions will need to be made. Keep it and spend the money to rebuild it right OR rebuild it to get it running and take it to carmax and trade it in. My main concern is reliability. I pull a boat all summer and don't want to break down again like last weekend with the family sitting in the grass on the side of the road in 100 degree heat!

I'll pull the heads next week and see. If I find a damaged block it might answer my question and I'll have to commit to a rebuild or a new short block. That will be a different thread....

Any thoughts?

 

New Data: Pulled the heads this morning and here's what I found.


Top left to right, cylinder 8,6,4,2
Bottom left to right, cylinder 1,3,5,7

Local guy is going to inspect both for $55. If needed will perform valve job for $70 more. If warped will have to get them leveled.

After inspection of the cylinders all look good but 2. They both look like something ran down the wall and etched it.


Question: can I get in there with 1000 grit sand paper and try to get the crap off or will I screw something up?

Put a straight edge on the block and have .003 gap in some places. Is that acceptable?

Local guy also said if it's need rebuilt a short block with new crank, rods, piston, rings, cam bearings, hot tanked, all machine work = $1350. I would use my cam and new lifters.

Or if I pull it apart, machine work would be $150 and the rebuild kit is $300. I put it back together. Not sure if I have the time right now...

Don and Good Heads in Roseville has been doing this for 26 years. Do these numbers seem fair?