Pics of my JB Weld job on a cracked block

A found a crack in my block. I looked into having it welded. I concluded that it's cheaper to go find another block from the same year and rebuild vs. trying to weld my block. If you try to weld a block the crack will spread. To avoid this you have to heat up the block. If you heat up the block you have to rebuild the engine when you are done and it's a bigger job vs. a normal engine rebuild. Or at least this is what some people say. End of story, I'm broke. Engine has fairly good compression. I didn't want to weld the block.

I went to the HAMB forum and asked for advice. The forum suggested trying JB Weld. I talked to other people that had done this and it worked. I decided to go for it. I thought I should come back to this forum and outline the steps that I did to use JB Weld. The forum was nice enough to help me. I'll take the time to come back and post how it all went.

To start, the crack is on the driver side near the oil pan. I think this is a common place where these blocks crack (when they do crack). I think this is along the water main. (so someone tells me).

First thing I did was get the block real clean. Gas first and a wire bush. Next degreaser. Next a wire wheel on a hand held grinder.

Next step was to put a grinding wheel on my hand held grinder and grind down the area. I actually ground away some of the splines that run top to bottom down the side of the block. But only the portion of the spline where the crack was. (see pic) I came back with a wire brush and got the area very very clean.

Next step was to take a torch and get the area real hot. This helped me see where the crack ended. In my case, because I ground the area semi smooth, when I heated up the block the crack got black and stood out.

Next I drilled holes on either side of the crack so it wouldn't spread. Someone told me to do this. They told me that if I don't the crack could spread more later. I tried not to go all the way through the block with my drill. I used a hardened drill bit and cutting fluid. It cut through the block like butter. If you do this, be very careful. You would be surprised how fast the drill cuts through the block. (unless you already know better). Not sure what drill bit I used. Less then 1/4" for sure.

Next I did something that in retrospect was probably pretty silly. I took a nail that had a double head (sort of) and I cut it down to make something like an anchor. I used JB weld to weld the anchor into the two holes I drilled in the block. I let the JB weld cure overnight. The end result sort of looked like I had hammered two nails into the block and left the head of the nails sticking out. But because there was essentially a nail head on both side you couldn't pry the nail head out without pulling all the JB weld out of the hole along with it. If that makes sense. Take a look at the pic and maybe it'll make sense. Not sure this was a good idea or not. After I did it seemed silly and seemed like overkill.

Next I took two packages of JB weld and applied them over the crack. I laid the block on it's side so that the JB weld would stay in place. I put plastic wrap over the JB weld and made sure the JB weld was fairly flat but I was fine with the JB weld not being perfectly smooth. I let it sit overnight.

Next I put another two packages of JB weld on the area. Again with the plastic wrap but this time I made a point to make the surface of the JB weld very smooth. I let it sit overnight.

Next day I came back and I sanded down the JB weld.

Next I painted the block with POR15 silver paint. I painted over the JB weld.

Take a look at the pics to see what it looked like.

We won't know how it turned out until I put the engine in the car and drive it for a few thousand miles. Wish me luck. If it fails there is a radiator sealer of some type that folks say works and I might try that. There is also another method but I won't try to explain it.

 

hate to bring bad news, but dont expect much from this. i can't see it holding up for very long at all. as in one or two heating up, cooling down cycles. it's going to want to expand and contract at differnt rates than the metal, then fail. hope i'm wrong though.

 

I put JB marine weld on my 440 block years ago. It cracked between the freeze plugs. I had the motor rebuilt and didnt pressure test or magna flux. Big mistake. When the motor was being broke in on start up found the crack. Still holding fine to this day. IF your repair doesnt hold consider using pins to repair the crack. I dont hear people do it much but you simply drill a hole in the crack and install a screw in pin and drill a hole next to the pin and repeat. It works but takes time. look at Lock n stitch in youtube on how to do it. good luck.

Dave

 

Yeah, I'm not too hopeful. But I have talked to several folks that said this worked for them. Wish me luck. I'm going to start looking for a new block right away. I want to learn how to rebuild an engine anyways. And like 41Gasser said, I can always try the pin trick.

 

http://www.youtube.com/watch?v=Pq0wfU4ZaKk

 

that is great. have you used this method?

 

I would guess that the JB will work. You need to plug a hole to the pressure of the radiator cap, which is what, less than 15 pounds? The heat cool cycles should not be that extreme. Not more than what the coolant is going to do.

I did a crappy job of welding a crack like that back many years ago. It still leaked a little so I followed up with block sealer. It worked too.

Finish up the rebuild and enjoy it. Like you said, worse thing is you may have to thow in some block sealer.

Neal

 

I think you should pressure test that before installation.

I know guys swear by JB Weld, but I think a crack like that is a perfect candidate for Lock-n-Stitch or Iron Tite.

See here:

www.locknstitch.com

www.irontite.com

 

That locknstitch is neat. has anyone ever used this method of repair?
Jay

 

I had a crack on the top tank of a plastic radiator and tried JB weld but it didn't hold. I was told it failed because of the different "thermal cycles" between the two materials. I hope it works for you but the cycles between a cast iron block and JB are very different.

 

One guy told me that there is some special TIG welding technique (using copper and steel wire) which allows to weld cast iron stuff

 

Plenty
http://www.locknstitch.com/Repair pdf files/Sea Escape.pdf

Something like this ^^^ is exactly what it's designed for. Can you imagine doing an engine swap on this? If the lock stitch method is good enough for a repair like this is good enough for just about anything. The question is can you access the damage to use the lockstitches, and will it "lock" in place ?

Some times it's easier to just get another casting, sometimes it ain't.

 

Plastic tank can be plastic welded if there's still some life in the plastic. It has a finite life expectancy. Same with the goofy plastic upper intakes. Need to do a cost analysis of the project though, it may be just cheaper to get a new part if labor costs are part of the equation.

 

I bought a '47 truck with he stock 216 that someone had slopped some sort of epoxy on a crack in what appears to be the same place. I never had any problems with it and I drove the truck for about 10 years before selling it.

 

I went to the HAMB forum and asked for advice. The forum suggested trying JB Weld. I talked to other people that had done this and it worked. I decided to go for it. I thought I should come back to this forum and outline the steps that I did to use JB Weld. The forum was nice enough to help me. I'll take the time to come back and post how it all went.



Thanks !!!

 

The shop I worked at years ago I was taught the art of " Lacing" this is where you drill and tap in an overlay fashion the entire crack doing both ends of the crack first and then working from one direction to the other,wire brush and grind clean ,you then use brass threaded rod normally 1/4 20 to insert into the tapped holes,grind down to surface level and you then braze over the entire area. I learned this from a master welder,and we never had a failed repair,did engines from one end of the spectrum to the other.
Yes it is time consuming ................but it works !!

 

I see it this way, 50/50 chance it will hold up. I had a buddy who owned a trans shop, a customer came in one weekend who was from out of state and had his trans case crack because he hit a piece of debris on the interstate. This guy wanted a "quick" fix because he was leaving in a few days and we couldn't find another case because it was the weekend. So we drained the trans, cleaned out the crack best we could and JB'd it and sent him on his way the next day. He called back later the next week, had traveled over 3000 miles and never leaked! Not sure how long it held up. I have another friend who owns a performance shop and has been building high performance Ford motors for about 40 years now, he told me he usually just welds cracks with just his mig welder, plain steel wire nothing special and has never had a crack leak! Good luck hope it holds up for ya!

 

My Uncle 'fixed" a block with JB Weld & traded the car at an auto lot. Couple days later the Dealer called & said not to come by his place again.

 

We have a four wheeler that had a big crack in a cylinder. From the inside to the outside. My uncle never changed the oil or put oil in it. We jb welded it. Hoaned it out. Put a new piston and rings in it. And it's run fine now for ten years or so.

 

Sometimes these things work...I had a set of heads on a vw I busted through while porting. I filled the intake runners with jb weld and smoothed them out no issues.. Car ran low 12s on pump gass and was street driven

Had one of my reps with a crack in a trans case. Drained it, cleaned it, roughed it up with a grinder, put a epoxy material over it, 2 years and thousands of miles later still workin.

Btw I use MM oil too ha ha

 

I don't know if yours will work or not but I suspect it will. I once bought an inboard boat that had JB Weld on a cracked block that was done a few years before I bought it. I kept the boat 5 or 6 years and the JB was still holding up fine. That was a marine engine though and it used fresh water as a coolant and probably didn't heat up as much as yours will.

 

Thanks for sharing your fix. Keep us posted.

 

Brilliant !!!!!

 

I've had terrible experiences with JB Weld. Don't hold your breath.

Next time I'll try road tar. Seems to take a jackhammer to dislodge it from the undercarriage.

 

My old friend has a 32 flat head block with two freeze cracks on the inside od the block. He was told by a flat head engine builder that the block was junk. Does any one know if this stick process will work?? Or any other ideas

 

Why is all this posted in the Introduction forum pages????

 

I never looked to see where it was posted. After the changes, I switched and go to the new posts and have gotten to prefer it. I guess I am not the only one that goes through the new posts.

Goes to show you can not post in the wrong spot. It will be found.

Neal

 

Thanks for all the comments. I plan to install the engine and run it and see how it goes. What the heck. I'll post after 3 to 6 months of driving it and let everyone know if it holds.

 

Some repairs sound incompetent but they can work better than one might expect:

Had a car hit a rock which split its steel oil pan in the mountains.
So I took a handkerchief soaked it in water and pushed it tightly into the hole with a screwdriver, put oil in the engine and drove it 150 miles home that night. It leaked no oil at all because water and oil don't mix. (the proper word is that they are immiscible).

After having cracked an aluminum oil sump on a motorcycle. I removed the sump, cleaned it with brake cleaner and dried it. This one I sealed with locktite 290 (the green stuff) It has held its oil for ten years.

Today I went to a highly regarded machine shop which is focused on fixing broken blocks and heads...their advice for a few small block cracks was: "If it was my engine I'd not heat it up welding it. Seal the crack some other way as welding has a high chance of warping the block and old cast iron easily cracks well away from the weld as the block cools. It can happen even if the block is cooled down slowly for two days." They also said that rusty cast iron can be miserable to work with as it gets very hard.

 

Did it hold up?