Cracked Block? It Has Good Compression

[Rubixone]

Can anyone verify for me that this is a cracked block??? It has good compression, and will run but the water jacket gasket was bad the third picture is a shot looking up from as if the motor was mounted on a boat looking up from the ground.

 

[F_R]

Re: Cracked Block? It Has Good Compression

Certainly doesn't look good, does it? To me it looks like a casting defect, but nevertheless, a crack is a crack, no matter what caused it. Big question is does it go clear through? I think I'd get the piston up on TCD and get some air pressure in the plug hole with some soapy water on the "crack" to see if I get any bubbles.

 

[Rubixone]

Re: Cracked Block? It Has Good Compression

Thanks fr I knew the soap and water trick just forgot, so thank you we all need a reminder.... well outcome is no bubbles. I cant see in the cylinder very well on in side but i don't see any scaring.... the water pump went out on this motor, melted impeller and water pump housing and water jacket gasket.... ouch... so i hope it doesn't expand the crack when it heats up cause it still runs pretty good.... any suggestions on healing that crack or should i just replace the water jacket gasket and run it till it dies????

 

[archcycle]

Re: Cracked Block? It Has Good Compression

Clean the surface and put some JB Weld on it

 

[Scott Danforth]

Re: Cracked Block? It Has Good Compression

could just be casting flaws.

 

[Rubixone]

Re: Cracked Block? It Has Good Compression

I was kinda wondering about the JB weld but wondered what could happen if it flaked off.

 

[boobie]

Re: Cracked Block? It Has Good Compression

Seeing it's next to the combustion chamber area, the JB weld may melt off. JMO

 

[Haffiman]

Re: Cracked Block? It Has Good Compression

The crack will have to be 'Dremmeled' and properly welded. If exhaust residue in the crack, you will need clean material to get anything 'stick'.

 

[boobie]

Re: Cracked Block? It Has Good Compression

Edit.

 

[jimmbo]

Re: Cracked Block? It Has Good Compression

For what's it's worth, This the Johnrude Forum, that is a Mercury engine

 

[archcycle]

Re: Cracked Block? It Has Good Compression

I was kinda wondering about the JB weld but wondered what could happen if it flaked off.

Seeing it's next to the combustion chamber area, the JB weld may melt off. JMO

JB Weld is great for things like that. I've used it on an exhaust manifold with no problems

Per the website it's safe for constant use at 500F.

 

[yorab]

Re: Cracked Block? It Has Good Compression

My guess is that it is a casting defect. As you mentioned, it is not causing a drop in compression, so I personally wouldn't worry too much about it. In my limited experience with old outboards, I've come across quite a few of these defects.