OMC 3L w/JB-Weld Job

[duck-man]

Long time reader, 1st time poster! What a great place to kill some free time at work!!!
Last spring I picked up an '86 17' Rinker 3.0L OMC "fixer-upper" with a +/-8" long crack under the exhaust manifold that had been JD-welded. I ran it all last summer with a slight dribble from the fixed area (just using the bilge pump occaisionally) and decided to remove the manifold and redo the JB weld in the fall. I ground it clean and v-grooved out the crack and did (I thought) an AWESOME job of JB and fiberglass cloth! Took it out last night and once it got up to temp. I checked and saw water dripping from the area under the manifold! It only appears to leak when running 3/4 to full throttle, so it's really tough to find on the water. Can't shove my head down there while steering the boat!
Tonight I'm going to use a light and mirror in the garage and see if I can tell where it's coming from for sure (I'm hoping it is just around the new gasket/manifold, but may be the JB job was not as great as I thought.:redface:

Any ideas how to verify where it's leaking (pressure test, etc.?).
Correct torque for the manifold bolts (didn't use any permatex...)?

Thanks for any tips you can provide.

 

[flashback]

Re: OMC 3L w/JB-Weld Job

just a guess duckman, but at the right end of the repaired area just below that pointer in the pic, it looks like a smaller additional crack (where the rust line is heaviest...

 

[duck-man]

Re: OMC 3L w/JB-Weld Job

That was a picture of my "prep" work last fall--before applying the new goop!
I thought it looked like the most recent leak was towards the front, but I will check more closely tonight.
Thanks for taking a look!
dm

 

[Windykid]

Re: OMC 3L w/JB-Weld Job

Ok, When repairing a crack, you must drill a hole at the end of the crack as to keep it from spreading further. And I would have it welded.

 

[Windykid]

Re: OMC 3L w/JB-Weld Job

JB Weld will not expand and contract like steel or aluminum. It needs to be welded or it will leak again I promise.

And have you done a compression test to verify no other cracks?

 

[duck-man]

Re: OMC 3L w/JB-Weld Job

Pulled the manifold off last night and found 4 or 5 little cracks in the JB.
Today I'm looking for a good welding shop!
Thanks again for your input.
DM

 

[dvan1901]

Re: OMC 3L w/JB-Weld Job

Might be cheaper, and definately more reliable, to just replace the block. if you have to take the engine out and pull everything off of it anyways to have it welded, you might just want to order a new block. You can probably get one for around $1,000 or so. Then you also have peace of mind and shhould not have to break it down again. Just a thought.

 

[duck-man]

Re: OMC 3L w/JB-Weld Job

You are most likely correct!
But I am the world's cheapest boater--I haven't figured out the "Break Out Another Thousand" theory yet!

 

[Windykid]

Re: OMC 3L w/JB-Weld Job

Most shops charge about $20-$30 per weld. They do have mobile welders.

 

[duck-man]

Re: OMC 3L w/JB-Weld Job

Now THAT'S in my budget!

 

[Wotknot]

Re: OMC 3L w/JB-Weld Job

I can see how that'd be in your budget.....but.......I kinda doubt you're gonna find someone to come to you, draggin their welder to do that job for only 20 or 30 bucks.......that is unless you've got a trophy wife in a bikini....

 

[redjmp]

Re: OMC 3L w/JB-Weld Job

To weld cast iron, it needs to be completely and evenly heated to red hot in a furnace and then welded and allowed to cool slowly.

 

[duck-man]

Re: OMC 3L w/JB-Weld Job

Yea, the shop I thought would be the best bet told me yesterday they don't even touch 'em anymore--and didn't know anybody that did. Too many that didn't work and only a few that did.
After looking at where it leaked from last fall's patch, I decided to give the JB one more try. I think a lot of the material "sagged down" and the repair was really thin at the top.
I ground it clean and dammed up the area with duct tape and then put on two layers of JB. Looks kind of cobbled in the pictures...I will give it a test run tonight and let you know how it goes!

 

[Windykid]

Re: OMC 3L w/JB-Weld Job

Don't want to be negative but I think you will have the same result eventually.