Cracked Powerhead

crem1

Petty Officer 1st Class
Joined
Aug 30, 2005
Messages
365
If you are buying a used motor, to be on the safe side is there an easy way to determine a fine or cracked powerhead?
Thanks
 

sschefer

Rear Admiral
Joined
Nov 13, 2008
Messages
4,530
Re: Cracked Powerhead

From the outside, it's tough to tell the difference between bad gaskets and a crack. Once you buy it and tear into it, it can still be difficult. There's a dye process that's used on aluminum to check for cracks and that's about the only way to be relatively sure. I had a block tested last year and it checked out fine but they missed a casting sand hole that looked like it was supposed to be there. After a lot of frustration I took it apart again and took it back to shop. We called Merc when we decided the hole was where the problem was and they said it didn't look normal.
We welded it up and it's was fine after that.

If you buy used from a seller that you don't know, it's a crap shoot. Most of the time the seller doesn't know.
 

crem1

Petty Officer 1st Class
Joined
Aug 30, 2005
Messages
365
Re: Cracked Powerhead

How much abuse and what kind does it take to generate a hair line crack?
 

crem1

Petty Officer 1st Class
Joined
Aug 30, 2005
Messages
365
Re: Cracked Powerhead

Could piston problems cause one?
Thanks
 

sschefer

Rear Admiral
Joined
Nov 13, 2008
Messages
4,530
Re: Cracked Powerhead

A plugged water passage and freezing is a real common cause. Folks think they have all the water out of them but a plugged water passage is holding some back. Winter comes along and the block freezes and that expanding ice cracks the block.

I think if a engine came apart inside enough to crack a block you'd see a lot of damage and probably not even consider it as a rebuild candidate.
 
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