Mercuiser 3.0 Block repair

[fishinrado]

Well guess it's on to the next fix after just replacing the gimble and u-joints.
A couple of summers ago I notice a few drops of water coming from underneath the manifold and eventually it caused a small rust stain on the block. Unfortunately last winter I had to store the boat outside and a trip to the lake the other day found the engine bay full of water. It ran great with NO water in the oil so I guess the good news it appears to be only an external crack. Just pulled off the manifold and will be doing the JB weld fix as I've read here. Will post some pics and results!
It's been a great family boat ( 98 Bayliner 1950 Capris) I bought about 7 seasons ago for a good deal and haven't really had to do much work on it so any more time I get out of it will be a bonus!!!!!
Onward..........

 

[Scott Danforth]

thermal declination cooling media expansion breach

 

[nola mike]

thermal declination cooling media expansion breach

...and subsequent iron oxide deposition.

 

[fishinrado]

LOL!!! Good thing there are Bilge pumps.........step 1 complete

 

[fishinrado]

The next few steps........drill holes, blow out w/air, 1st layer JBweld

 

[Bondo]

Ayuh,..... Looks Good,.... Hopefully, it'll hold,.....

With that crack sealed up, it's possible the added water pressure could expose an internal crack,.....
So check yer oil often on yer shake-down cruise,....

 

[fishinrado]

Will do! Did 3 separate light layers with a light sand/clean in between and a 24 hr dry period. Taking the opportunity to clean plugs, arrestor, wires etc. well at least she looks good! Will water test tomorrow and if that’s good will test at a small lake. Will update as I go....

 

[fishrdan]

Acetone test your manifold and exhaust elbow while they are off the engine, to see if they are cracked also.

If the block cracked because it wasn't drained, was the manifold full of water and frozen too?

 

[fishinrado]

Well all go so far.........No internal damage to report as of today. Been on the Lake 3 times now and ran the crap out of it last night. Oil clean and not one damn drop of water anywhere! She is running better than ever it seems so I'll keep checking on things as I boat. I really believe the time-taken method worked for me. I think the key is getting it super clean and doing a light emery cloth sand and acetone wash in between coats. It was a pretty good crack and was protruded as well so if it worked on mine this method should work on most external cracks. I also found a hair-line crack in the lower manifold and repaired that at the same time.
Will keep posting as the season rolls on........
Thanks to the Iboats forum folks for all the great info!

 

[fishrdan]

I also found a hair-line crack in the lower manifold and repaired that at the same time.

Did you acetone test the manifold? If the manifold has an external crack, it could have an internal crack too.

An internal crack will leak water into the engine = BAD. This isn't repairable with JB weld, the manifold would need to be replaced.

 

[gergAlicious]

So how does the acetone test work?

 

[fishinrado]

 

[fishinrado]

See the above drawing posted here........ I did do this and all seemed well! I repaired the external crack first.
And honestly I couldn't tell if was a hairline crack or a manufactured casting line.
Took it out again tonight and it's running great!

 

[fishrdan]

That's the proper procedure for acetone testing (fill the manifold and see if it leaks) but you need to use acetone. Water has surface tension, and won't seep through cracks that acetone will.

Better to be safe and test the manifold, since an internal crack will lead to internal engine damage.