Hairline Crack

[Eagle43]

I'm in the process of rebuilding my 1951 flathead. After ordering new rings and bearings I discovered a hairline crack between #3 cylinder and the exhaust valve. Now I'm considering my options. This seems to be a very low mileage engine. The bores are still standard and show little wear. The crank has been ground 0.010 under. The con rod bearing show some copper but the mains look fine.
Any advice from anyone. I contacted Lock-n-Stitch who sells pinning kits. Hopefully they will advise me what to do. Does any one have any experience fixing cracks like this?

[big job]

What does it look like in the cylinder in regards to the piston 'at the top' I have
seen a lot worse and they ran and ran forever.

[Frank Miller]

The first order of business with a flathead is to clean and magnafux the block. You have one crack you discovered so at that point I would correctly check for more. The block is worth fixing if that is all you have. If you were near me i could recommend someone.

[Charlie ny]

Eagle,
I had 2 cracks just like your photo shows, we sleeved both bores and installed seats. I ran that motor hard in my '41 and now 12 years later it is my shop test motor.
Charlie ny

[rotorwrench]

A friend of mine ran an engine shop up in KS catering to the irrigation engine operators. A lot of them were using the old 549 International engines on their pumps for years but the parts began to get hard to find after IHC stopped supporting them. He pinned more heads and blocks than anyone I've ever know since just to keep them going. They would last a long time running for weeks on end during the summer months with very few problems due to pinning repairs.


Some folks pin down the cylinder wall and don't even install a sleeve. Others insist on a sleeve to insure a good seal and reduce warranty issues. Either way, it can be repaired effectively as long as the repairman can reach both ends of the crack. Hardened valve seats would be required under any condition in an exhaust valve pocket repair.

[budmanroch]

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Originally Posted by Charlie ny

Eagle,
I had 2 cracks just like your photo shows, we sleeved both bores and installed seats. I ran that motor hard in my '41 and now 12 years later it is my shop test motor.
Charlie ny

I'm amazed it can be repaired. I have the exact same crack as EAGLE43 running from the cylinder wall of #3 to under the hardened valve seat and the valve guide. Machine shop told me it was junk. I was constantly overheating and using a gallon of water every 10 miles. When I tore down and found this crack I thought that was the explanation. It seemed like my cooling system was way over pressurized even with a 4# cap. I theorized that the compression was going through the crack to the water jacket. The crack didn't show on a pressure test at 80 psi but it was clearly cracked once the block was baked. Is my thinking wrong? that compression doesn't bleed into the water jacket? I didn't see any leakage on the head gaskets when I pulled them. You think this can be fixed...? What does that cost - ball park wise?
Bud

[oldford2]

Originally Posted by Frank Miller

The first order of business with a flathead is to clean and magnafux the block. You have one crack you discovered so at that point I would correctly check for more. The block is worth fixing if that is all you have. If you were near me i could recommend someone.

[B]To properly pin a crack takes experience. You can not just buy a kit and go to it. Too many pitfalls can happen. Broken drills, broken taps, wandering holes, etc.
As Frank mentioned, post your location and maybe someone can steer you to an experienced mechanic. I have had 3 blocks pinned by the fellow Frank has alluded to in Millbury, Ma and he has been doing this for over 40 years.
John

[supereal]

We find cracks in almost all old engines brought to our shop. We hot tank them, then Magnaflux to make all cracks visible. Finding the usual cracks in the valve pocket area allows us to repair with threaded pins. Blocks which have cranks into or near the water jacket are junked. We replace all valve seats, and sleeve only a bore with a crack near the top. All blocks are then resurfaced. This not an expensive process, but blocks are becoming scarce and pricey.

[Bob/Ohio]

Here are some pictures of a Jeep 6cyl. water jacket crack, that a friend of mine and I did a Lock & Stitch repair on last year. Jeep is still going with no problems. This will give you and idea of how the Lock & Stitch system works. We have used both kinds of pins. This type is a bit more expensive. I know your crack is in a different location, but the repair is basically the same.



Bob

[Ol' Ron]

Frank Casey fixed several cracks like that, and I did't even have to sleeve the cyl.

[John R]

Bob/Ohio,
That's an excellent looking repair.

[AnthonyG]

I remember in the late '60's when a Tool & Die apprentice, one of the seasoned Tradesmen Tool & die Maker's had a early '50's Merc. w a Flathead. Don't remember all the specifics but quite a lot as I was hungry to learn. He had a cracked block and repaired it the same as we used to repair cast Iron jacked parts on some of the Die cast & injection mold machinery we used in Mfg. Drilled a small hole 1/16th" ant either end of the crack, clean abrasively and with chemicals then flux heat and Braze then depending machine if required. I remember him bringing the engine in partially disassembled, no oil pan, manifolds or heads. couple of pistons and connecting rods removed from the problem area I think it was 2. Dipped engine in a vapor de-greaser then followed the above mentioned procedure. I was an apprentice and he was training me at the time. It worked and remember him driving the car till at least my graduation 3 yrs later. He drove it every day. I moved on and lost track of him.

[Andy]

I let a 90 Olds 307 freeze up and split both sides out from heads to pan. I V'd the cracks a little and ran continious beads with my arc welder from the tops to the bottoms. High heat and nickle rod. Ran for years with absolutely no problems. I hated that car. Tried to tell the dealership when I traded but they thought they knew everything. It probably never gave any trouble. Oh, and I did not take anything apart.

[oldford2]

Originally Posted by Bob/Ohio

Here are some pictures of a Jeep 6cyl. water jacket crack, that a friend of mine and I did a Lock & Stitch repair on last year. Jeep is still going with no problems. This will give you and idea of how the Lock & Stitch system works. We have used both kinds of pins. This type is a bit more expensive. I know your crack is in a different location, but the repair is basically the same.



Bob

Maybe I am missing something in your repair. I am under the understanding that the screws must interfere with each other. in your picture there is a space between the holes so the crack is still there???

[JSeery]

Originally Posted by oldford2

Maybe I am missing something in your repair. I am under the understanding that the screws must interfere with each other. in your picture there is a space between the holes so the crack is still there???

Think you are just seeing a step in the process, look at the finished product.

[Bob/Ohio]

John R.
Thanks for the reply!


Oldford2
Yes they must interlock with each other. I have step by step pictures of the repair, as the owner requested pictures of the repair when we did it. I just posted a few random pictures of the repair. You can see the jig they sell in the second picture, this indexes the holes so the pins will be in the correct locations to lock. JSeery is correct, all pins are in and ground and finished. All that was needed was a coat of paint. 27 pins in this repair. The drilled holes you see in the first picture were done to see how thick the casting was. You need to tell them this when ordering the pins, so they can determine which pins you need.


Bob

[oldford2]

Originally Posted by Bob/Ohio

John R.
Thanks for the reply!


Oldford2
Yes they must interlock with each other. I have step by step pictures of the repair, as the owner requested pictures of the repair when we did it. I just posted a few random pictures of the repair. You can see the jig they sell in the second picture, this indexes the holes so the pins will be in the correct locations to lock. JSeery is correct, all pins are in and ground and finished. All that was needed was a coat of paint. 27 pins in this repair. The drilled holes you see in the first picture were done to see how thick the casting was. You need to tell them this when ordering the pins, so they can determine which pins you need.





Bob

Okay. I got it. John

[Eagle43]

Originally Posted by big job

What does it look like in the cylinder in regards to the piston 'at the top' I have
seen a lot worse and they ran and ran forever.

I contacted Lock-N-Stitch and a representative responded. He asked for some measurements. This morning he phoned me to say that in his opinion this was not a job for an amateur. The only real fix would be to send the block to them in Turlock, CA (from Alberta) and they could fix it. The main problem is the design of the block with not enough material between the bore and the valve. The flat area is only 0.25" wide. The total distance from bore to valve seat is about 0.6" - see second picture. The crack seems to extend about 0.6" or more into the bore - see first picture.

I've come to the conclusion that the best option is simply to ignore the crack, put the motor together, and hope for the best. The parts (bearings, rings, valve springs, electronics) have already been ordered and paid for and it will cost me shipping to send them back for a refund.

I don't expect that this truck will see a lot of miles anyway. Mostly it will be going to car shows and on club tours and maybe a few trips to the lumber yard.

[JSeery]

Originally Posted by Eagle43

I've come to the conclusion that the best option is simply to ignore the crack, put the motor together, and hope for the best. The parts (bearings, rings, valve springs, electronics) have already been ordered and paid for and it will cost me shipping to send them back for a refund.

I don't expect that this truck will see a lot of miles anyway. Mostly it will be going to car shows and on club tours and maybe a few trips to the lumber yard.

That is not an option that will work! The cylinder would require a sleeve and the valve seat would require an insert if you are not interested in stitching the crack. You would also need to drill the ends of the crack to stop it from spreading.

[tubman]

Back in the '60's I re-ringed a block with 7 such cracks. It was running fine when I sold it a couple of years later. I will admit that I must have been lucky and also that I purchased a lot of "Barr's Leak" over that time. ("Re-ringed"sounds bad, but "re-rung" sounds worse.)