Cracked Block between cylinders

[TO30 in NC]

Continuing saga. '52 TO30 has been running real hot for some time. Noticed the #4 exhaust manifold flange warped (due to studs pulling). When I pulled the manifold and head (unusually difficult to get off), I noticed there are hairline cracks between 1&2, 2&3, 3&4 Cylinders. It was surprising because there has been no loss of compression in any cylinder and the oil has not been contaminated by coolant (although there is some coolant consumption).

Any similar experiences? I'm not ready to replace the block even if I could find one. Suggestions before I rebuild?

Thanks,
Steve

 

[Anonymous-0]

I haven't faced this issue but - if I did - I would first consider pinning the block to keep everything in place. It is easier to keep it where it is supposed to be than bringing it back. Next, I would try really hard to find out why it was overheating. Of course, the first things to check are the radiator, water pump and thermostat. If those are clean, functioning, and installed correctly, I would put some organic acid in the block cooling passages and see if it has unusually thick deposits. Same for the head. If the cooling hardware looks OK, inspect the valves to see if they too have overheated. If they have, look to an air/fuel or timing problem. Search the archive for how to evaluate those issues. The next may seem silly, but, if the engine systems seem to be OK, see if the brakes are dragging.

Anyway, that is how I would start and, with good compression, I wouldn't jump to a rebuild unless the bearings are toast. I would redo the head once it is off.

 

[gshadel]

Cracks between the cylinders on top the block are often not a death nail for the block. Cracks between the cylinders on the bottom of the block are much worse, pretty much require attention of some sort, like pinning or brazing. The top cracks are basically sealed by the head gasket and held in place by the head bolts and head. I've heard more than 1 guy that just ignored the top cracks, installed new head gaskets, torqued down the head and ran a can of block sealer.

Make sure your head is not warped, and the block top deck is not warped. Sounds like your TO engine has suffered. The cracks are likely the result of the overheating, not the cause of the overheating. You have some other problem, like a dirty radiator or bad thermostat.

If the top deck of the block is still straight, what I've done is grind out a V on both sides of the web between the cylinders (inside the block), clean,clean,clean, them use several heavy layers of metal re-inforced epoxy to build-up the web, then grind it back so the sleeve will just pass so it can be installed normally into the block. Use some head gasket sealant, install a new head gasket and your good.
This means pulling the sleeves to do this work.

I did that about 5 years ago on mine. I was rebuilding the engine anyway. Never a problem since.

George

 

[Jerry/MT]

This is a common problem with Continental Z blocks. My original engine had similar cracks between #2 and #3 and between #3 and #4 and had tension rods through the water jacket in 3 places to pull the cracks together. I never had a problem with oil contamination from coolant. I replaced that engine (because it was worn out) with a remanufactured short block that had the cracks furnace brazed repaired. I have about 300 hrs on that engine with no problems. I might add that my TO-30 is a working machine on my ranch, not a show machine.
It only takes a single overheat to cause this problem, unless you have a defective casting. As long as the cracks don"t propagate you should have no problem.