The Stovebolt Site Forums The Shop Area Engine Shop 235 cracked block

Has any one had any luck with JB weld cracked block. Block has hairline crack on drivers side inline with drain plug.

I have heard somewhere it works, but have never tried it.

My 216 had a crack on driver's side, just above oil gallery, a good 10-12 inches. Had been JB-Welded when I bought the truck, but leaked regularly, but minorly. Engine was rebuilt this winter. With block out, and cleaned, the shop allegedly wedged out the crack and filled it with DevCon (supposedly harder/better than JB). Sadly, with engine mounted back in truck, it is still dripping to varying degrees, depending on engine temp.

I have elected to live with it - once again - and study it more to determine what action to take next, possibly fix-a-leak stuff.

A friend has an Olds six cylinder from '29, also with a crack that has been patched, AND leaks.

I'm coming to the conclusion that it's VERY hard to permanently repair a crack in the block. :mad: Best you can do with engine in truck, drain it, dry it, clean it, and try the JB. Not too much effort for the potential gain. Just don't get your hopes up too much.

My (cynical) opinion, anyway . . .

-Michael

Thanks, it is kind of what I figured it would be. May be I will try to get it welded.

If you do a search on this topic, you will find quite a few stories of success with JB weld for this problem. The early 216s use to corrode and crack in that area.

The only true fix for it is to weld it up. Plastic just isn't going to do it. It will have to be removed, ground to a V, cleaned and heated to several hundred degrees then welded with iron rod.

Devin

Tschall,

JB Weld has sealed a small crack in my 261 block for about 10 years. The 1" crack is above the casting plug on the manifold side of the block.

I first drilled a small divot (hole) at each end of the crack; then v-ground the crack; then cleaned the area very carefully; and finally covered the crack with JB Weld from divot-to-divot.

I'll admit that I think I am lucky, and I expect the leak to recur at any time. However, it was worth a try and it has held up beyond my expectation.

Tim

K&W Block Sealer

Mine was welded and it still leaked before I got it.
Buddy at NAPA told me they have some good metal epoxies that will work.

I drained mine and put in water and used a sealant. Ran it until it was hot a couple of times and then drained it and refilled with anti-freeze and it seem okay so far.
I would try to seal it from both inside and outside before I went the welding route. I am also cheap.

you could look into the plug and stitch method. i have used this method with great results.

It looks like mixed feelings on this subject and now i am wondering if it is time to think about installing the 72 250 i have on hand. Would like to keep every thing from trans back. I have heard if i rework a sb bell housing and a new cross member engine mount it should work in my 48 chevy.

I repaired a small crack on my MGA with JB weld and ran it that way for 12 years of so. I swapped the block last summer and had the old one welded as a spare. I cleaned the weld and covered it with JB weld just for good measure. Make sure you clean it with a wire wheel or something to get all of the crud out. If it is in an area that you can work on without much trouble try it. If it doesn't work put the other motor in.

Drilling tiny holes at both ends will help prevent the crack from propagating. Here's some good info:

http://www.locknstitch.com/

I did the same sort of repair you are looking at a few years ago with JB weld. I followed all the good ideas the others are naming here, drilling, wire brushing, veeing the crack, preheating, someone even mentioned hooking up a shop vac to the drained radiator during the repair so the goo gets sucked into the crack. The repair worked great, but after sitting through a winter I noticed a bit of seepage again, which I still have.
But I just keep driving the old 216, checking the water regularly. Sooner or later I expect to drop in another motor, but in the meantime I'll keep running with a little colant leakage. Why not, every other engine fluid leaks too... but the dang thing runs great!