The Stovebolt Site Forums The Shop Area Engine Shop Welding a cracked block???

Got a call from my machine shop yesterday...they just got done magnifluxing the head on my 235 and said they found a small crack. Can't remember exactly where they told me the crack was because I was too busy cussing under my breath. I do recall it is not on any of the cylinder walls. They mentioned that there are companies out there that can re-weld a cracked block (didn't know this was possible)... Normally this would be a no brainer decision for me to scrap the motor, but it is the original motor for my 55 1st series.
Anyone had any success (or failure) with re-welding a cracked block?

Any info/opinions/etc greatly appreciated.
Thanks,
-Paul

My old 216 cracked severly enough that my machinist uncle wouldn't guarentee that it would hold. That said, yes, it can be done. However, if you are considering any performance modufications to that engine, it's better to shop for a better block, I've been told.

DrewP,

Not gonna hot rod this motor...It is going to be a restore to factory spec build. Just want to be sure before spending a ton of money on machining & rebuilt that I won't have a catastrophic failure on the open road.

Thanks,
-Paul

Is the crack on the head or the block?

The big issue with welding a head or block is that the grain structure of castings is different than that of rolled materials. To be properly performed, the item (block, head, etc) needs to be heated to a high temp before welding. Then to preserve the tensile strength it will need to be heat treated after welding. This is sometimes refered to as a "foundry weld". NOTE: almost all castings have some welding performed during thier manufacture.

If properly performed the results will be equal to that of the original casting. However it may be expensive.

If this is not performed properly additional cracking may be experienced in the future.

If as you say, it is in the head, then get another head and you are OK. To my mind you still have the original engine. If it was in the cylinder wall of the block, you could sleeve that cylinder. Elsewhere in the block is not so critical, and I would think you could fix it by "Stitching" or weld it with muggywelding rod, or even use JB weld.

When I took my head to have it done 25 years ago, the shop said it had a crack after magnifluxing it. I had them go ahead and rebuild the head anyway, as I could not see a crack and it was working OK. Still working OK.

Kurt

Just called the machine shop...the guy who found the crack is not there today, so I wasn't able to get a definitive answer. They were able to tell me that the crack is indeed in the block and is external. (I haven't seen the block yet to verify location, but plan to very soon) They speculate that the crack was possibly caused during freezing temperatures at some point in the engines life. Not sure if that helps any.

Paul,

The 216 in my big bolt fire truck was a replacement for the original engine, which froze and cracked in the water jacket.

This 216 ALSO has a crack in the water jacket - exterior. We rebuilt the engine, and JB-Welded the clean block while it was out.

Still leaks some when it gets warm. I'm happy to live with it. The coolant isn't under a lot of pressure, and it's cheap.

I've been told stitching works well. I'd go that or JB Weld, and keep the original block. Dripping coolant here or there is just marking its territory.

-Michael

LONGBOX55 mentioned in an old thread once about drilling and tapping a hole and threading in a pipe plug. Grind down, drill half through the plug and tap. Insert another pipe plug. Repeat down the entire stitch. Of course it also depends on where the crack is located...

For some reason that always seemed like an ingenious way to handle it. In my defense, it was several years ago and my memory doesn't quite remember.

Not to mention the fact that the search feature sucks no matter how hard I try to use it and with whatever combination of words I use I can't find that thread...

Jeff

Weld it or sew it, doesn't really matter, but get somebody to do it who knows what he's doing. Weld repairs need to be done by the preheat-weld-post heat-peen method, where the block is brought to a moderately high temperature with a torch, then a short section of the crack is welded with nickel-alloy rod, them heated again, and stress-relieved by peening with the pointy end of a welder's slag hammer as it cools. I like to keep my welds to 1/2"-3/4", and peen the weld for about 5 minutes before doing the next section of the weld. Once the entire crack is welded and peened, heat again, then bury the block in sand and let it cool overnight. The preheating, peening, and slow cooling prevents stresses from forming that will cause the block to crack right next to the weld from cooling too fast. "Sewing by installing overlapping threaded plugs is a lot simpler if the crack is in a place where it can be drilled and threaded.
Jerry

Stiching a block is a no brainer, for the guys at a machine shop that is. I bought a boat a few years ago that had "milky" oil on the dipstick....tell tale sign of a water jacket crack. We pulled the motor tore it down, took it to the machine shop and for $100 they stiched it up and have been using it for 6 years now with no problem. If there is a crack in the block I would think there maybe one in the head as well. Have them stich it, you'll be happy, and you can hardly see it!

Jerry's description is spot on. The peening is not random so when watching someone who "knows what he's doing" they massage the metal while soft much in the same way a physical therapist would work out a knotted muscle. Lot's of stitching info here:

http://www.locknstitch.com/cracked_engine_block_repair.htm

Thanks for the great info guys... I finally made it over to the machine shop so here is an update. It is not a small crack. It runs almost the length of the block on the manifold side. ( Engine pics Hope the link works...) I spoke with the machine shop for quite a while on options. First we discussed the stitching method. Because of the length and location of the crack I do not think this is a solution to my problem. If it were a small crack on a flat surface it would be different. Second we discussed having a qualified company with the proper equipment weld it up(after reading some of the material fellow bolters provided I won't be attempting this myself).

Which leads me to my dilemma...based on the pics is this block worth fixing/welding up???

Thanks,
-Paul

It depends on what your future plans are for the truck. Are you going to show it and have it judged? Is it going to be a driver? If you plan on driving it and enjoying it then a replacement block would be the way to go. It would make sense to hold onto the original block with the matching numbers for your truck. I would think that your cash outlay for a replacement would be far less than having your block repaired.

That one's a pretty classic freeze crack. Unless you have a specific reason for wanting to reuse that block, I'd suggest finding one in better shape. 235's aren't particularly scarce or valuable- - - -there should be plenty of good condition replacement blocks available. I've got several of them stored away if you're interested. Drop me a PM if you like.

There's a company called "Diesel Cast Welding" that does excellent quality crack repair, but they're pretty pricey. The machine shop where I used to work used them extensively for repair of high-dollar Cummins and Cat blocks and heads. I'm sure you could get that crack repaired by someone with their capability, but it would cost several times what a replacement block in better condition would run.
Jerry

Don and Jerry,

Thanks for the info. My goal for the truck is to make it how it rolled off the assembly line. Don't want it to be a trailer queen, but I will be driving it to shows,etc. I am thinking about what Jerry said... Finding a replacement block may be the way to go and just keep the original block just in case. This may seem over-the-top for some, but if I can find a late54/early 55 truck block date coded around the time my truck was made I will be happy. I don't know the odds of actually finding this block, but this is the right place to find one if there is one out there. The cracked block I have is a 3835911 truck block F55X...anyone have something similar for sale???

Jerry...I sent you a PM.

Thanks,
-Paul

Maybe you could get your truck retitled using the donner block number. Turn it into a different truck, where everything has been replaced except the block.

When folks ask if it has the original engine, you can then say "yes" LOL

Kurt

If you find the right year block/complete engine with the correct casting numbers you can file the I.D. serial number off and stamp it with the number off your old block. Replacement blocks from Chevy didn't have numbers stamped in them. You took your numbers and stamped that on them. You would still have the correct year engine in your truck.

Your DMV should be able to help you get it re-titled on the body number. In MO, you just have to have a friendly law enforcement officer look it over to verify nothing is amiss.

Looked at my title...its titled under the body number not the engine number which is a good thing. Now I just need to find year/casting number correct truck motor.