The Stovebolt Site Forums The Shop Area Engine Shop Cracked block challenge

For a few dollars I picked up a 235 engine that had a cracked block.(no stamped #`s on dist. plate Tagged with 060 bore. casting #8764476.)[img]https://www.stovebolt.com/ubbthread...er/51462/filename/IMG_20230103_142848715 Alt1 w measurements.jpg[/img][img]https://www.stovebolt.com/ubbthread...er/51462/filename/IMG_20230103_142848715 Alt1 w measurements.jpg[/img] I don`t need to use the motor as I already have a spare in good running condition. I have used a few parts off it for my run stand. Trying to decide weather to try and rehab the engine or scrap the shortblock. I have read the many posts on fixing the cracked water jacket. What I have and the questions I am seeking answers or opinions :
14 inch crack total with about 6 inches displaced 1/8 to 1/4 inch wide. Hairline crack the remaining area.
Head off, oil pan off, on engine stand. Internals dirty but moving freely, have been oiling cylinder walls lightly with Marvel mystery oil.
Intrigued by the Stay Brite silver solder fix as I am an advancing metal worker.
Will I need to remove the internals (Pistons crank etc ) in order to avoid damage by bring the block up to 400 degrees to get the solder to flow and will it likely flow well into the hairline cracks?
Better to order marine tex or similar and try to just execute the patch despite the displaced cast iron.
Will a patched block with intact and functioning engine really have any market value or better to save the good internal parts, head and sheet metal and try selling cheap and avoid the process of trying to save a damaged block?
Appreciate any and all comments!!

During my career as a machinist, I have brazed many pieces of cast iron back together. The issue I see is getting the crack clean enough to get solder to stick and flow. Cast iron is really porous so any oil or anti-freeze be difficult if not impossible to remove. When brazed, I would vee out the crack to get to clean metal. Once clean, it brazed beautifully.

In my opinion, the crack is way too big to effectively fix and as a buyer I would steer clear. Save/Sell what is good, and scrap the rest. You’ll save yourself a big headache.

I'm with Phil. That block has been bored to about the limit on cylinder oversize, and that crack is pretty severe. You'd spend more in fuel to preheat it that it would be to buy a usable block without a crack. I've tried brazing a cast iron valve cover from an old engine and it was a total failure.

Thanks fellas ,I`ll take your advice and ditch the block, save myself some time and money. Maybe spend that time trying to figure out how to rebuild a carburetor.

I'd try selling it before scrapping it. Way too many of these have been scrapped in the past, they are not making them any more. I know a fellow that could fix that for around 300 or so. He is the best in the area, that is if he's still around, he was about 3 years ago.
When he welded cast iron you could not tell it was welded. He did many parts for the out fit I worked at back in the day, never had them break or crack either.
Over bore is a minor issue to a machinist, that is what liners are for.
Brazing works but welding is better.

Swami A truck came to me with an epoxied crack at the top like that. It ran fine for quite a while and never did leak but if I were you wouldn't put a lot of time and energy into that one. There are blocks out there.

That is way more than just a crack in the water jacket. Its bowed out and looks to be nearly big enough to sling a dead cat through it.

I agree that sometimes a repair is possible.
The problem I see is that you won't know if it works until after you spent $$$ on it. If the fix fails, you have to do all that work over again also.

I've been considering trying some cast iron repair using nickel alloy wire in my MIG welding machine. The old tried and true method of "pre-heat- - - -weld- - - -post heat- - - -peen" and then bury the part in sand to slow cool overnight seems to be the best way to deal with the nasty habit of cast iron to crack right beside a repair. I'm thinking of skip welding 1/2" beads with a MIG and peening after a pretty good preheat to stress relieve and doing a slow cool-down. A long crack like the one in the picture might take a week or more to get a full repair. Once the crack is welded, a coat of Marine-Tex and pressing a piece of 40 grit sandpaper over the fill as it's curing to put the textured appearance back into place will hide the repair and seal off any pinhole leaks.
Jerry

One thing I don't understand is, I have read that outfits that use thermal cleaning of cast iron blocks and heads use about 700 deg F in an oven to do so. I would think that could cause warpage etc. Anyone have experience with that?

A high volume rebuilder in Nashville used thermal cleaning on their blocks and heads, followed by a tumble cycle in a stack of big truck tires to clear the ash from the castings. Other than a permanent BBQ odor that couldn't be rinsed away, I don't recall them having many problems. Of course, the thermal cleaned parts got a detailed inspection and full machining during the rebuilding process.

Full machining ? You mean the normal stuff? I highly doubt they will fully machine any engine block. Lifter bores would have to be sleeved, pan rails, front and rear faces, and main bearing seats would be a mess as well as getting the caps to fit the tight fitting, register, or sides, I don't think anyone doing normal engine rebuilds has the machinery to do that or would spend the huge $ on new bearing caps etc.
Wow truck tires? I bet that made a mess of them, they'd need hot tanking to get the embedded rubber out of the pores.

The engines were bored, sleeved if needed, line bored if necessary, crankshafts reground and balanced, rods reconditioned, rocker arms replaced or reconditioned, and generally brought back to factory specifications or better. They offered a 2 year, 25K mile warranty, with extended warranties available at extra cost. I installed dozens of their engines, and only had problems with one, which had a camshaft ground out of spec by one of their suppliers. They sent me a new cam and lifters and a gasket set, and paid my labor to swap the cam.

Several big rig tires were bolted together into a long tube on a rotating fixture, and the blocks and heads were tumbled inside to shake the ash from the baking process out of them. It worked very well. Grooms Engines started out as a speed shop in the late 1960's, and by the 90's they were turning out 30-something rebuilt stock engines per day. Roger Grooms retired and sold the business to some yankee outfit, and the quality took a nosedive. I quit using their engines after that.

Truckrolet A machine shop I worked in would get repaired heads from a company that would weld right thru cracks in valve seats. When you ground the seat it would be just like the rest of the head smooth and clean weld.

Same as the guy I mentioned. Sent him a head that had a valve destroy the whole combustion chamber, head came back and looked brand new.