External block crack (small) - marine Tex or JB Weld or other??

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tmh

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I'll skip the sad, long story of my engine's past..... Bottom line is I have small (1-2"), thin cracks on both sides of the block a few inches above the drain plugs that leak very slowly. I will not be replacing the block so I want to try to fix as best i can. I read A LOT here and elsewhere on this and many feel there is a decent chance the fix will last - maybe longer than my 23 year old boat. the key seems to be to sand/grind then clean very well as prep. Then the patch.

My question is, what to patch with? I read some have successfully used JB Weld some say Marine Tex (epoxy). My mechanic (not the one who caused the crack, btw) says he'd use marine tex because it does well at higher temps.

What do folks think here? JB Weld? marine Tex? other? IF "other" please let me know where I can but it if it's a less common product.

Thanks as always.
 

turborich

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Re: External block crack (small) - marine Tex or JB Weld or other??

I would try the JB weld. It has always worked well for me.
 

jaxnjil

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Re: External block crack (small) - marine Tex or JB Weld or other??

drill the ends with a small drill to keep them from growing. grind paint off and follow crack making a slight trough on top it. if you can't braise, jb weld
 

CheapboatKev

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Re: External block crack (small) - marine Tex or JB Weld or other??

I used JB weld on my Harley years ago, worked freakin great and never had an issue at all..I would use it as well in a marine enviroment. As you stated, the key is the prep work.
 

HappierWet

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Re: External block crack (small) - marine Tex or JB Weld or other??

My vote is for the marine tex. We've used it on blocks, heads, a waterpump, a cracked transom(altough that didn't work so well...too much flex) the idea about drilling holes at the end of the cracks is a good one though. I'd also grind the cracks out a little. You don't want just surface putty.
 

jerryjerry05

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Re: External block crack (small) - marine Tex or JB Weld or other??

If it only leaks a little why worry.If it doesn't leak into the oil then no problem.
The block expands and contracts with heat and cold so any patch other than a weld will probably pop off after time.Jerry
 

Bondo

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Re: External block crack (small) - marine Tex or JB Weld or other??

I'll skip the sad, long story

Ayuh,...

I caught it in the other thread,...

If it's cracked down low by the drains, it's Freeze Damage,... Period.....
And,...
If it's leaking Only to the outside,...
You can just wait for the rust to fill it in,+ it'll stop leaking,...
Or,..
You can lay on an epoxy patch on a properly prepared surface,...
Choice of Glue, is Your Choice,... They all work,..
I'd just go mix alittle with resin,+ filler...
 

Dakota47

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Re: External block crack (small) - marine Tex or JB Weld or other??

put a couple layers on when doing it.:cool:
 

SPOONMAN1

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Re: External block crack (small) - marine Tex or JB Weld or other??

Old timers would drill and pin the crack, overlapping the pins to keep them from coming out, would seal the crack and last longer than the the engine.
 

lkbum

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Re: External block crack (small) - marine Tex or JB Weld or other??

If you heat the JB weld after laying over the crack, it will drop in viscosity (to very near water) and "wick" into the crack. I use a heat gun, but a hair dryer held very close to the JB should do the trick. Experiment first by laying a bead of JB weld on the block somewhere other than the crack. Then hit it with the hot air. You'll be surprised, it will become runny. As soon as you pull the heat off of it, it will go back to paste consistancy. Careful not to overheat it (very unlikely on the block). If you do, it will offgas/boil and become porous.
 

achris

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Re: External block crack (small) - marine Tex or JB Weld or other??

I have done a 'cold weld' on a broken starter motor mounting bolt hole (V6 Mercruiser) about a year ago. Still going strong and not even looking like cracking again.

I used a MIG welder set to a fairly high current. I ground the crack out slightly and then just gave it a touch of weld, like one spot. Then waited for the area to cool down and did another spot. Did that about 6 times and ended up with a repair that you would have difficulty picking.

Chris...........
 

tmh

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Re: External block crack (small) - marine Tex or JB Weld or other??

OK, thanks all. looks like I have a few options to consider - I'm not doing this until spring as the boat is winterized and stored already.

I think I'll be OK as long as i prep it well because the cracks are small enough that even without a patch they barely leak. Unless it worsens, it has no effect on cooling water flow. I'm not nearly as paniced as when the mechanic told me "you have a cracked block" the first time.

The heat idea sounds good because I'd think it's impossible to put on while too runny, but a brief heat to make the "putty" flow a bit into the crack should be good.

Thanks again.
 

Maddness038

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Re: External block crack (small) - marine Tex or JB Weld or other??

hello,
I have Larson Senza with a volvo penta 5.0GL and I'm going to start off and say that i have 2 really big cracks on each side of my engine block, in the shape of an H. i did a little bit of research and concluded that these are freeze cracks and they gush water everytime the engine runs. i read a few forums and wondered if i could repair these with some good 'ol JB weild, and if not could you give me some advise on how to fix it?
 

Don S

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Re: External block crack (small) - marine Tex or JB Weld or other??

Welcome to iboats madness038
It's best to start a new thread of your own when you can't find answers you need in old posts.
Please do not post to old threads of someone elses with your question. Your question will become lost in no time.
 
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