Welding Cracked Engine Blocks

jclark178

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Jan 1, 2016
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Has anyone had any experience of welding a cracked block if so what procedure did you use and did you have any problems. I know a lot of guys just use jbweld etc but I would like to repair one by welding it--Think it would look a little better than all that goog on tacked on the side of it...
Thks
 

Bondo

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but I would like to repair one by welding it--

Ayuh,.... Welcome Aboard,.... As a life long Welder, it ain't worth the time, 'n effort,....

It cracks again 'round the weld, 'n ya end up slatherin' it with epoxy anyways,.....

Just skip the weldin', 'n go right to prep, slather, 'n finish,...
 
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bruceb58

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Mar 5, 2006
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There are people that have done it but that doesn't mean it isn't also cracked on the inside.

Personally, I would never trust a block that has been cracked.
 
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thumpar

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Jun 21, 2007
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The only time I have hear of a success is when the block had been heated in an oven but you have to take it apart first.
 

Bt Doctur

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and if using nickle cast rods the block would have be cooled gradually back to room temperature
 

StarTed

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If it's cast iron it can be heated in a wood burning stove before welding while on top with nickel rod then thrown back in and let cool as the fire goes out. I did that to a Land Rover exhaust manifold and it never broke again. However I bolted it to a large flat plate to help keep it straight.
 

Rick Stephens

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The only time I have hear of a success is when the block had been heated in an oven but you have to take it apart first.

Not worth the effort usually - guess it depends on how expensive it is to find a replacement block. Can't tell you how many rebreaks of welds on blocks I have seen - lots. A few successful ones on big diesel blocks where a furnace was used to control temps before and after welding. Once tried welding a Perkins diesel in an 80 ton crane. Pre and post heated with torches, seemingly forever. Ended up pulling and replacing the block in the end. You don't even want to know how much that cost on site.
 

keith2k455

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Maybe I've worked in engine factories to long and with s large manufacturer too long, but I would never weld a block or head, nor would I trust one that had been welded. I suppose I'd epoxy one just to buy a little time and see how it goes, but I still wouldn't trust it. I'd also look up a good tow plan with this type of repair
 

StarTed

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I wouldn't recommending welding a cast iron engine block unless there is no replacement.

I've read where there is an official method of drilling, tapping and inserting threaded pieces and doing it again and again overlapping each one down the crack. It's supposed to work but I've never tried it.

Aluminum blocks is another matter that I have no knowledge or experience with.
 

Bondo

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and if using nickle cast rods the block would have be cooled gradually back to room temperature

Ayuh,.... Did that once on a sailboat diesel motor riser, cracked, 'n rotted,....

Change the regulator on my gas grill to an adjustable hi-pressure style, 'n fired it up,....
Baked the piece til Good, 'n Hot, then started openin' the grill hood, 'n layin' in a 1/4" at a time, closed the hood, 'n go back in 10 minutes or so,....
Towards the end, I preheated my kitchen oven to 500?,.....
Once I was done stitchin' up the piece, I moved it to the kitchen oven, 'n lowered the temp 50? every 1/2 hour or so,.....

It Worked,... it lasted quite a few seasons, til the boat was sold,........

I've read where there is an official method of drilling, tapping and inserting threaded pieces and doing it again and again overlapping each one down the crack. It's supposed to work but I've never tried it.

That works Great on heavier castin's,.... Not so much the thin water jackets on motors of the last 70 years or so,....

This last winter, I repaired a edge flange of a door for an ole Round Oak potbelly stove,....
Thin stuff,...
The missin' area, maybe 5" , 6" long, by up to an inch wide, had rotted/ rusted away, from bein' buried in dirt for God knows how long,....
I clamped a hunk of aluminum, bent just so, to it to support the new weld, 'n started tackin' it together,....
One drop of 99% nickle rod at a time,...
Many hours, or days in-between drops of weldment,....
Draw an arc, see the droplet, pull away,... go do something else,....

Also welded a top to bottom crack in the lower fire ring castin',....

The door looked pretty good, the fire ring not so much, but well connected, needed a slather of furnace cement when the stove was assembled, 'n pointed,...

Aluminum blocks is another matter that I have no knowledge or experience with.

Ayuh,.... Much easier,....

I've done Harley blocks, 'n heads for a few motors,....
 
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dieselram94

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Apr 14, 2010
Messages
94
I have welded up one 350 Chevy block at the holes to mount starter. I remember heating it and I used the nickle rods. We controlled the cool down after I ran a hard facing rod over the top. With the holes cracked could never keep the starter from deflecting while cranking. I welded it up and it never broke again. As far as I know that motor is still running around somewhere. It out lived two vehicles it was installed in...
 

flipbro

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Feb 8, 2013
Messages
830
If you try go with the mig weld aproch. CROWN ALLOY 44-30 preimium NICKEL-IRON-MANGANESE cast wire. Use argon gas much more reliable. Arc with NI rod is a 50 50..
 
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