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Author Topic:   Cracked block
powerglides
Dirt Full Roller

Total posts: 69
posted February 20, 2002 07:51 AM
I purchased a motor with a cracked block (frozen) Cheap. Has anyone had luck welding one up? I have nothing to loose really. I have heard that you preheat with a torch weld with a mig then peen or tap on the bead while post heating. then use pure water and ceramic block sealer to finish any pin holes. how does this sound?

freeland63
Dirt Roller

Total posts: 15
posted February 20, 2002 03:31 PM
Ive heard of drilling and tapping series of holes, and then pinning them with scew in pins that draw the crack together and then sealing it with epoxy. my engine builder does this as a service and I only think It works on the outer water jacket or lower crankcase.Im would have to get ahold of him to find out where to get the pins

Monster
Dirt Maniac

Total posts: 135
posted February 20, 2002 06:39 PM
I have never seen a successful repair done with an electric welder, not to say it couldn't be done. I have seen successful repairs done with a spray-weld(braze?) process, to the extent that I bought a setup to use to repair heads that I have found water on while porting. Successful prep and preheat is the key to a good job. It takes me about a week to work up the courage to do it, and I bat about 50%. I use a gas grill to preheat, then pack the head in vermiculite to slow the rate of cooling. It takes a GREAT deal of skill to do, but then again, what do you have to lose?

BK19
Dirt Freak

Total posts: 285
posted February 20, 2002 06:48 PM UIN: 40696038
is it cracked in the lifter valley? if so drill the ends of the crack take a die grinder with a round burr to the whole crack then burn the oil out by using a torch and use JB weld it works great!

Flatlander
Dirt Freak

Total posts: 310
posted February 20, 2002 06:56 PM
Ok Ya'll are gonna Laugh If it's in the lifter valley take a small die grinder clean it out and use an epoxy sealer on it theres only about 8 or 9 psi in this area you can do this on the outside also BUT I would only do this when there are no more options The best way is to use another block I have used these methods with sucess but I was worried every time I ran it

Donnie Ross
Dirt Maniac

Total posts: 109
posted February 20, 2002 07:36 PM
most machine shops can do this with pins called castmasters, the crack is drilled and tapped the threads are rolled to pull the crack together each pin is supposed to hold 1000 lbs check out the web site under cast master my 406 was repaired this way with no probs.

sideways
Dirt Freak

Total posts: 273
posted February 20, 2002 08:17 PM
Hey BK19 could you elaborate a little for me on the"take a die grinder with a round burr".I was wondering how much was needed to be cut?Or are you just smoothing the crack up?Or veeing it out?Thanks for the help dint know it could be fixed.

dirtracer14
Dirt Freak

Total posts: 499
posted February 20, 2002 10:46 PM UIN: 23443678
I had a block that was cracked all the way down the side we used the block sealer concrete and filled it up to the top of the crack never had a problem. Now with the jb weld deal we used it in side the lifter gally also on another cracked block and after time it lifted off...not sure if it was fronm the presure or from the oil. It was in the block for about 2 years befor it started to lift just what i have run across!!!

Flatlander
Dirt Freak

Total posts: 310
posted February 20, 2002 10:53 PM
Yeah I was always a little nervous with that just didn't have an alternative at the time but it never did give us a problem

hughes
Dirt Maniac

Total posts: 141
posted February 21, 2002 06:32 AM
A crack in a block or in a weld is just like a car window----- it will run. Just as some old school folks would take a window cutter and make a small slit on the glass parallel to the run to stop it, the same principle applies. (Pends on the size of the crack) I would take a small drill bit and just barely past the end of the crack, drill a small hole so if the crack runs it will run into the hole and that's the end of the line. That way the crack won't run any more after you have patched it.

BK19
Dirt Freak

Total posts: 285
posted February 21, 2002 07:08 PM UIN: 40696038
yeah you are basicly vee'ing the crack out so the jb weld will hold better it doesnt last forever but it will last longer then you think

neverenoughbrew
Dirt Forum Racer

Total posts: 82
posted March 04, 2002 01:43 AM
I have seen blocks welded up before,but it takes someone with alot of skill. I know of only one person capable of this. My point being,it can be done, but not by the majority of people. Pinning it with screws is the most common method. This method has been used for many years. My Dad 40 yrs ago repaired a 3 and a half foot crack in a deisel locomotive block by starting before the crack and finishing after the crack,drilling,tapping,run bolt in,grind head off,drill out half of bolt just installed,tap,run bolt in,grind head off,drill out half of bolt,tap,ect,ect,ect,ect,ect, interlocking the bolts. That engine was in service for many 100,000's of miles with no problems.

Dunbar
Dirt Maniac

Total posts: 119
posted March 08, 2002 04:11 PM
quote:
Originally posted by powerglides:
I purchased a motor with a cracked block (frozen) Cheap. Has anyone had luck welding one up? I have nothing to loose really. I have heard that you preheat with a torch weld with a mig then peen or tap on the bead while post heating. then use pure water and ceramic block sealer to finish any pin holes. how does this sound?

I bought a 389 from 1 of my friends and it had a cracked block. we took it to 1 of my friends and they welded it up with nickle rod. the motor ran for 2 yrs and is still running. I even had the motor to 260 degrees and the crack never reopened. just go get some nickle rod and weld it up.

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