OMC Head crack

[Sugo]

Hello,
I removed my cobra 3L inboard to change the rear main seal. Once I had the flywheel off I noticed the frost plug was pushed out. (due to the unexpected cold weather before I had a chance to winterize it). Upon further inspection I concluded that the block had not suffered any serious damage, however I did notice a hair line crack on the rear end of the head. The crack is about an inch long. I noticed a small water drop that had come from this crack. The head was just rebuilt before this happened. Are there any other repair options rather than replacing the head?
Any ideas would help.

 

[Northernbob]

Re: OMC Head crack

Well no suggestions. I will let the pros chime in on that.
I would want to bet there are going to lots of freeze damaged boats this year due to the two cold snaps we have had in B.C.

 

[ricovw]

Re: OMC Head crack

i see you are in victoria. Cool, me too!! I have a 3l aswell...

 

[a70eliminator]

Re: OMC Head crack

Use a high speed dremmel with a small grinder tool and V groove the crack end to end, then fill with liquid steel, it would be best to have it welded with nickle rod, but I've heard many people say liquid steel does the trick just by smearing it on the crack without even a v groove.

 

[Bondo]

Re: OMC Head crack

Ayuh,... Before I wasted my time fixin' what you found,...

Drain the block,+ Pressure test it with Air,...
The crack you found is in an Unusual area...
I'd sooner think there's More cracks in more common areas, that you haven't found Yet...

If the Pressure Test confirms that, That's the Only crack,...
JB weld or Marinetex will fix it,... Usually...

 

[fishinpa]

Re: OMC Head crack

IF You find this is the only ! crack it should be drilled at the end.

end of crack drill hole approx. 1/8 inch then do the quick repair on it ..

Too weld it and make a good solid repair the head would need to be removed.

fish

 

[ENSIGN]

Re: OMC Head crack

First check the oil level,if it's higher than normal you possibly also have a internal crack.Regardless have the block and manifold pressure tested.

 

[Sugo]

Re: OMC Head crack

Thanks for all the good info guys, A pressure test determined I have a cracked block as well as a cracked head. I just purchased this boat and assumed the water had been drained. I won't make that mistake again. I also assumed that it needed to be colder for this kind of damage to occur. The temp dropped to -5 (C) degrees during the night and around freezing during the day for a few days. The frost plugs on the side of the block did not even pop out. The crack to the block was about 5" long. I did not see it during a visual inspection as it was high on the block hiding under the manifold. I hope this thread might save others some headaches.
Cheers,

 

[Silvertip]

Re: OMC Head crack

If the crack extends down the surface of the head that faces the block (the gasket surface) junk the head as an external patch will not hold. If that's the case and you want to try, use a dremel tool and extend the groove into the gasket surface of the head about 1/4 inch or so. Seal the crack and then surface the sealer in the gasket area. When you install the head, use a liberal coating of gasket sealer in that area and bolt it down. Since this is a 4-banger, if the fix doesn't work head replacement can be accomplished quickly without pulling the engine.

 

[fishinpa]

Re: OMC Head crack

If the crack extends down the surface of the head that faces the block (the gasket surface) junk the head as an external patch will not hold. If that's the case and you want to try, use a dremel tool and extend the groove into the gasket surface of the head about 1/4 inch or so. Seal the crack and then surface the sealer in the gasket area. When you install the head, use a liberal coating of gasket sealer in that area and bolt it down. Since this is a 4-banger, if the fix doesn't work head replacement can be accomplished quickly without pulling the engine.

Thanks for all the good info guys, A pressure test determined I have a cracked block as well as a cracked head.

 

[HT32BSX115]

Re: OMC Head crack

The frost plugs on the side of the block did not even pop out. The crack to the block was about 5" long. I did not see it during a visual inspection as it was high on the block hiding under the manifold. I hope this thread might save others some headaches.
Cheers,

Sorry to hear that.... It probably won't however..... save others the headaches that is!

Most people don't come to this site until AFTER they've had a problem!!


Oh...



It's a minor point but, Those "FROST" plugs are part of the problem in that people keep calling them "Frost" plugs.

It's an interesting colloquialism that possibly makes people think that they actually protect against cracked blocks (....... they don't and were never intended for that purpose)


It's been getting to -13C here for the last several days....


Cheers,



Rick

 

[Silvertip]

Re: OMC Head crack

Yup -- the correct term is "core plug" and the holes are put in the block so the casting sand can be removed from the water jacket area after the block is cast. Generally if a core plug is pushed out due to freezing, that's not all that happened. -12 degrees in southern Minnesota today so I hope all of the folks who have an I/O sitting along side their house have their winterizing done. If not they have my deepest sympathy and the next words we hear from them would likely be "oh crap".