Fixing cracked block 3.0 mercruiser 4cyl

[Taylor94]

Our 1990 sea ray mercruiser 3.0 has a block crack. See picture. Best way of fixing it just to last to the end of the summer.

 

[Scott Danforth]

buy a $300 motor and replace the improperly winterized one you have as the exhaust manifolds are probably also cracked and busted.

 

[fishrdan]

I bet the manifold is cracked too, rusty water in the head intake ports 3 and 4, most likely came from cracked manifold.

JBwelding the cracked block might work temporarily, might not too if there is an internal crack.... You can't JBweld the manifold, or weld it, it needs to be replaced if cracked. Fill the manifold water jacket with acetone, and see if the acetone leaks into the intake or exhaust ports.

A new manifold is going to cost around $300, so best bet is to find a good running complete used engine as Scott said.

 

[Taylor94]

Manifold is fine just pulled it off. Obviously replacing the gasket but it looks strong.

 

[Bondo]

Ayuh,..... You can clean it up, 'n epoxy it,.....

Odds are once ya seal up the outside, 'n the passages can fill up with water,..... it'll show ya the cracks Inside the motor,.....

 

[Taylor94]

What about getting a drimmel and J.B. welding the crack to just make it last through this summer then fix it over the winter?

 

[Taylor94]

Anyone know where to look for a 3.0 4cyl used motor anyway?

 

[Scott Danforth]

Look on craigslist for free boats with rotten hulls. May also be called free trailer (must take boat)

Most entry level I/O boats have a 3.0 in them

Worst is spend $1000 on a boat/trailer combo. Sell the trailer for $300, sell the drive for $500, part out everything else, and scrap the hull and you may get the motor for under $200

 

[Bt Doctur]

theres one in central nj exit 9 njtp

 

[Taylor94]

Well we JB welded it. Hope it sticks long enough for this summer. It’s a big ole crack

 

[Scott Danforth]

The problem is the 3.0 also cracks inside the crank case

 

[Taylor94]

Wouldn’t there be water in the oil if it cracked inside?

 

[Scott Danforth]

not initially, however wait until you get that motor warm.

 

[Taylor94]

Manifold gasket replaced, crack jb welded, new gas. Started right up and was running smooth then died again. No water leaking visible. Any ideas??

 

[Scott Danforth]

check the oil to see if its going up or getting foamy white like a milk shake

 

[grizzreaper]

Hey Taylor94. Where abouts are you. Since everyone on here helps us newbies with our many problems.i have a 86 3.0 140 hp that's seized. It's all stripped down to the Pistons, cam shaft and timing chain. If you live in Canada n in Ontario I will give you the block.