Muggy Weld 77 Rod

[Greg-nwo]

Father in law has a crack in the engine block of his old truck he restored. It's a very small hairline crack but is leaking coolant into the oil. A welder has tried to repair it but was unsuccessful.

I was looking into the problem a bit and came across this company. They make a welding rod for welding cast iron that supposedly solves the issue of the cast cracking on either side of the weld as it cools. Just wondering if anyone has any experience with their products?

 

[blue dog]

I have no experience with these products but am very intrigued by the 72 and 77 rods for cast iron. We truss dana 60 axles for the desert and welding to the cast center section is something that is a real specialty.

 

[e-tek]

I just went through all this after the original block cracked on my 1946 Merc truck:

http://www.garagejournal.com/forum/showthread.php?t=44766&highlight=merc

The key to welding cast is to heat the surrounding metal enough prior to welding, then a SLOW cooling process, usually in a sand, or vemiculite, pit.

Here's an awesome tutorial by a member (goodfellow) here:

http://www.*@#$*@#$*@#$*@#$*@#$*@#$*@#$*@#$*@#$*@#$*@#$*@#$*@#$*@#$*@#$*@#$*@#$*@#$*@#$*@#$*@#$/index.php?topic=68.msg339#msg339 Of course it's on the "other" site and won't show here.....jeeze.....


That all being said, I've heard that this kind of weld on blocks are rarely successful. The best method of block welding is called Lock n stitch: http://www.locknstitch.com/cracked_engine_block_repair.htm

The best method in the long run though is a replacement block.

 

[Displaced Hokie]

Looks interesting...I've always thought there HAS to be a better way than is required currently.

 

[blue dog]

I have only welded axel center sections, with that being said, have never been successful in the long run. I have pre heated, welded 1' at a time, let cool slowly, and they still crack later. We even had a center section break a section just outside of the weld. I was wondering if the cast piece becomes to brittle from the heat of the weld. We are trying to weld 4130 to the cast section. they hold for a while, but all ways crack or break later.

 

[Greg-nwo]

Supposedly with this 77 rod the weld is more elastic than the standard nickel rod you would use on cast. The weld is able to cool and not pull the cast in and crack it further.

I'll let you know how we make out if we decide to try them on the block. He had a spare block lined up but that went to the scrapper earlier this summer unfortunately

 

[slipknot]

so no one has tried it yet? im interested in seeing if it will actually work got a buddy who had a crack in his exhaust manifold ( and i tried to repair it and it just kept popping so i said the hell with it)

 

[Greg-nwo]

I'm ordering a box of rods today to try on the engine block.

Friend of mine is buying half the box to try a repair on a cast iron cement mixer part he broke. Probably be a while but I'll let you know how it goes in both cases.

 

[Joe From NY]

check this out http://www.cut-like-plasma.com/info_welding_cast_iron.htm

you don't need that torch, but the rest is good info. Most important to PREHEAT, then slow cool. I set up a rosebud torch when i had to preheat a cast iron manifold. "V" the crack after drilling a small hole at each end of the crack to stop spread. Also see http://www.millerwelds.com/resource...ad.php?12147-pressure-tight-cast-iron-welds&?

 

[e-tek]

I have only welded axel center sections, with that being said, have never been successful in the long run. I have pre heated, welded 1' at a time, let cool slowly, and they still crack later. We even had a center section break a section just outside of the weld. I was wondering if the cast piece becomes to brittle from the heat of the weld. We are trying to weld 4130 to the cast section. they hold for a while, but all ways crack or break later.

How "slowly" are you cooling it? For the best results, you have to bring the entire piece to at least 1000F, then cool it OVER 24 HOURS or so. You need to bury it in a sand/vermiculite pit to get that kind of slow cooling. I've welded manifolds and a heat exchanger like this and it's held - but I've had a few crack too....

 

[gorilla]

I've had some good luck TIG welding cast iron with silicon bronze rod which is more of a brazing process than welding. I've also repaired some engine blocks and cylinder heads with cast iron TIG rod. Never had much luck with exhaust manifold it seems that the leaking exhaust burns all the iron away and when you strike an arc the manifold just burns away.

 

[three arms]

Old Flathead guys used to tap the crack and then insert a bolt and saw it off. You make a long line of them side by side. Seriously. It should be on the internet. I have tapped holes larger and used plugs. Sometimes low tech works when high tech won't. I'll look around for the link. If it's just a small leak, you could just braze it. Lots of old tractors with burst blocks worked for years with gobs of brazing rod down the sides of the block. Tensile strength of brazing is nothing to sneeze at. All you need for that is a torch, rod, and flux. And patience. Come on, you're trying to salvage something. Think what the old timers did. New timers just toss it and get a replacement part.

 

[Joe From NY]

How "slowly" are you cooling it? For the best results, you have to bring the entire piece to at least 1000F, then cool it OVER 24 HOURS or so. You need to bury it in a sand/vermiculite pit to get that kind of slow cooling. I've welded manifolds and a heat exchanger like this and it's held - but I've had a few crack too....

Right on. For an old cracked MGB manifold repair once, I made my own poor man's kiln out of firebrick and a tulip propane torch head. I went to my local concrete yard and bought a few dozen of those beige bricks that they use to line a fireplace. i laid them out on my driveway and made kind of an open alcove shape to put the manifold on and placed the torch head facing it and fired it up. it is like a mini-blast furnace. Get one of those real cheap IR thermometers, to see when it is hot enough. After welding the crack, i dropped it into a galvanized metal trash can that i otherwise use to burn all my bills and mail with critical data on it. i had it partly filled with the vermiculite (real cheap from Home Depot, or any garden supply place). Then just dump more vermiculite on top of the part, cover the can and forget it until late the next day.
i guess this long story is not very helpful when tackling an engine block, but that is how i did my piece.

Check out this guy on Picassa. He used the Kast Weld 111 cast iron rods and O/A to fix his rear axle. It looks like it came out great for him. He even has photos of the firepit he built for heat.:

http://picasaweb.google.com/jjzanin/Ford88RearendBuildup02#


Now here are some photos of what i used:

 

[e-tek]

Old Flathead guys used to tap the crack and then insert a bolt and saw it off. You make a long line of them side by side. Seriously. It should be on the internet.

This is what spawned Lock n stitch....

If it's just a small leak, you could just braze it. Lots of old tractors with burst blocks worked for years with gobs of brazing rod down the sides of the block. Tensile strength of brazing is nothing to sneeze at. All you need for that is a torch, rod, and flux. And patience. Come on, you're trying to salvage something. Think what the old timers did. New timers just toss it and get a replacement part.

Actually braze doesn`t offer much tensile strength itslef ( brass, or braze mixes are generally `soft`metals) , but rather offers the ability to `weld`dissimilar metals, to `fill`vs melt cracks together and allows some expansion and contraction.

 

[Greg-nwo]

Update: No go on the block that was cracked. Same thing happened.... small cracks in the cast to either side of the weld. I wasn't there when it was welded and didn't get many details so not sure if they pre-heated much etc.

 

[e-tek]

Oh well, at least it was tried. I just recycled my original block as the crack was way too big to even try.

Another engine was $300,

another blocks was $125.

 

[speed bump]

This is what spawned Lock n stitch....

Actually braze doesn`t offer much tensile strength itself ( brass, or braze mixes are generally `soft`metals) , but rather offers the ability to `weld`dissimilar metals, to `fill`vs melt cracks together and allows some expansion and contraction.

Done with the proper technique brazing will produce joints that fail in base metal with similar strengths as welds. I know the power company here considers any coupon that fails in the braze a fail.

 

[gorilla]

The Devcon corporation makes several epoxy products that might solve the crack problem, they have little structural strength but will patch a leak. I repaired a crack in the water jacket of a BMW many years ago with it and as far as I know it's still holding water. Have you tried something like Bars leak? A guy I know used a product to seal up a cracked block in an old GMC truck that required him to add it to the coolant, run the engine then drain the block and leave it vented to the atmosphere for 24 hours. I don't remember what the product was, he got it from the local engine machine shop. Good luck.

 

[Greg-nwo]

He has found another block so he's going to get the motor rebuilt with it.

He did look at some of the sealant type products but wasn't too confident in them and didn't want to be ripping the motor apart again if they failed. I probably would have tried something like that but his call not mine