Bondo'd Block

[yoss]

Unpacking my boat for the summer I discovered that I did a poor job during my prepurchase inspection. The previous owner actually covered a crack in the water jacket with bondo. I've got a '98 malibu response w/a mercruiser 350 magnum, I already dremel'd off the abomination and I'm going to JB weld it as a stop-gap - What kind of options do I have here, I'm assuming I can just swap onto any 350 block I pick up? I knew the guy had a walnut sized brain when he showed me that he had 1 side of an isolator connected to the accessory battery and jumper cables running to the main but I didn't imagine he'd done something so amazingly retarded and dangerous. Next time I'll pay a mechanic to inspect!

 

[TilliamWe]

Re: Bondo'd Block

I doubt it's actually body filler, as that wouldn't stay put with water forcing against it. But JB weld is a good idea, but if there are internal cracks, you are going to have to replace the block

Regarding swapping any 350, no. You do have some model year restrictions. In 1987 GM switched to a one piece rear main seal. This causes them to have a different number tooth flywheel in comparison to all the Small Block Chevies made from 1955 thru 1986. That means a different starter, also. Also in 1987 they changed to the heads that have a 72 degree angle for the inner two intake manifold bolts on each side, it requires a very specific intake manifold.
Then in 1995 they introduced Vortec heads. These are the best motors to have, but they require yet another different intake manifold, as the bolt angles are completely different and there are only 8 intake bolts, not 12. Also, somewhere they started making all the blocks able to use a roller camshaft. But I am not sure this dates all the way back to 1987. It might only be when they went to Vortec heads. Someone (or several people) on here knows the answer to that.

So if your 98 boat truly has a 98 motor, you'll want a block from 1995 and up. Then all your components would switch right over.
Good luck.

 

[wca_tim]

Re: Bondo'd Block

good advice above. as an aside, you'de be surprised what bondo will hold up to. When I was a kid, I fixed several things with it that had no business holding together - including a broken water jecket assembly on the side of an outboard engine. I just didn't know better, didn't have you wonderful people to ask for advice and it was what I had on hand...

 

[TilliamWe]

Re: Bondo'd Block

I guess body filler (Bondo is a brand name, like a Band Aid) could hold for a little while. But Body filler can not get water from the backside and stay put in a sheetmetal panel. That's why you can't repair rust holes with it, and expect them to last. Filling dents, yep it'll stay in forever, but not in a hole.

 

[stonyloam]

Re: Bondo'd Block

I have been doing some research on fixing a cracked block for an old 47 Jeep Flathead engine block and came across this: http://www.ahmperformance.com/crackrepair.html ,assuming that you are not getting water in the oil (internal crack), a repair by metal stitching might be something to look into. Good luck.

 

[yoss]

Re: Bondo'd Block

It definitely was body filler most of it came off by hand and what was left was soft, light brown and rubbery covering a crack that could be a twin to the one in that link. No water in the oil and it ran like a champ all summer long last year so I'm hopeful JB weld will get me through the season and then I guess I have to source a vortec block(thx TilliamWe) from somewhere, my suspicion is that it won't be too hard to find one at a wrecker - I'll obviously have to find someone who knows more about v8's and marine engines to learn from - no leaks in the manifolds by the way and I couldn't find any obvious repairs in them. The bondo was still holding up....I've seen a boat sink before though, no thanks

 

[proshadetree]

Re: Bondo'd Block

Have it welded.You can get iron rods or I have migged a few never had a problem yet.

 

[TilliamWe]

Re: Bondo'd Block

I am with stony and proshadetree, repair what you have, you may never need a block.

 

[yoss]

Re: Bondo'd Block

you guys have been really helpful so far I thought I'd give you a little update today , JB Weld patch held up well I ran it about 20 minutes on the hose with no leaks except for a trickle draining down from the port manifold(of course) that I never noticed before so I am going to yank it in a couple of days and have a look(praying its a gasket.) If I have to take the block out its getting replaced the only way I'd go for having it pinned is if it stayed in place... welding from what I've read is really not recommended on cast iron, the only other option I haven't seen much about is soldering , anyone have any experience w/that??

 

[fat fanny]

Re: Bondo'd Block

Welding cast done with the right precautions and proceedures can last forever the key is the right filler material and pre and post heating of the weldment.

 

[Bondo]

Re: Bondo'd Block

Ayuh,... Stiching, or welding both have their own Problems,..
Fixing it with plastics is the way to Go.... Done Right,.. It'll last Forever...