Block crack repairs

Bob/Ohio

Bob/Ohio

Senior Member
Seems to have been much discussion lately on crack repairs in Flathead blocks. Here are some pictures of some recent repairs I did on an 8ba. I had to replace a leaking head gasket and found many cracks in this block, more than I have ever seen in one, pulled the other head and found the same thing. Found areas that the cracks were almost into two cylinders, and also heading to the valves. I wanted to try and stop these cracks from going any further, so I decided to plug them. I used Irontite plugs and also bought some gold Magnaflux powder, recommended by them to be sure I found the end of the cracks. The powder works well for small areas using just a strong horseshoe magnet. So far no leaks, bubbles, or water in the oil. I think I used about 20 plugs in this block. I know some of the cracks could have been left alone, but I plugged all I could. I posted this because some people have never seen these type of plugs used. Hope this helps.

Bob
 

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These are drilled and tapped and then ground flush? Are they tapered like a pipe thread? And can we do them at home without a machine shop?
 
You can do these with no problem at home. Plugs are tapered, and you need their tapered tap. After the plug is in tight, you cut it off leaving it proud about 1 or 2 threads, then you peen the plug with a small hammer, working the material around to blend it into the block, file smooth to surface, then I used a stone to finish the repair. I bought a box of 100 plugs (smallest amount sold), Tap, Magnaflux powder + applicator bulb, for around $150.00. If you have to use a full length plug you will need their tapered reamer also. Some of the areas in the block are going to be blind holes, and others will not. We also made our own tapping jig and drilling jig. Make job easier. Irontite will sell you what ever you want, other places will only sell you what they say you need!
Bob
 
Its called stitching weve been doing it for years on all different blocks. The plugs come in different sizes, small to large. All are tapered.

Harry
 
Interesting thread Bob,
Do you happen to have any pictures "in process", and would you be so kind as so post pictures of the tools you used?
Thanks
 
The only other pictures I have are some of the block before repairs were made. If you look at a copy of Vern Tardels new book he shows some pictures of the repairs. Go to Irontite website and you can see the taps, reamers and plugs. If you need pictures something else, I can take get them next week when I get back to the shop.

Bob
 
Here are a few more pictures of the block "before".
 

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Nice Job! We used some of these plugs on our Flathead Cadillac race engine - if properly applied, they work really well. They even make large ones (kind of like pipe plugs) that are used for fix stripped stud holes - which we needed a couple of. Nice products and good people (especially if you go direct to them). They will also do the work - if you bring them the block.
 
Bob, will you please update this thread after you get the engine installed and driving with your results for the repair? I have a 59A block that has a lot of cracks and have entertained this type of repair. I don't think I would want to pay a machinist to install them all, probably cheaper to find another block. It would be nice to have a practical example.
 
Very nice!
Seems like a way to bring back a cracked block back to life.
Is there any history for the longevity of this type of repair? Does the block material just eventually break down due to age? Interesting thought on 80+ year old engines?
 
This engine is just a spare that I have. If I put it in something later on, I will post the results. I currently have it on my run stand with about 3 hrs run time, and no problems so far. For an engine that has sat for over 30 years, it runs and sounds pretty good, with great oil pressure, and so far no water loss. I would guess by all the cracks that this engine was overheated more than once, especially with the blown head gasket on one side. There was so much buildup of gray sludge on top of number one piston, and in the combustion chamber, that the engine had a knock in it. If you turned the engine by hand, it would stop when number 1 piston was at TDC. The head bolts were very loose on that side when I pulled it off. I just couldn't see putting head gaskets in it, without trying to do something with the cracks.
 
It is very gratifying to see someone pull this off with apparent success. Congratulations on a job well done. One question : are you a professional machinist or just a guy working in his home shop like most of the rest of us?
 
I have a 59ab in a tonner pickup I bought last winter. Also sat about 30 years according to PO's nephew. It was stuck, but not badly so I changed the oil, got it running and it ran real nice... Until I put a radiator and water in it. It quickly overflowed the oil pan with tan colored whipped pudding out the breather. I'm too busy with other projects right now, but I am trying to learn about cracked block repair. As quickly as the pan filled with water it may be cracked pan rails down deep. Would these plugs work in that area? On another note, I once ran a log splitter that was mounted on a truck's rear axle by the lug nuts. This was a large steel cone with a coarse spiral thread and a very sharp tip. The log round was thrown against the wedge which split the piece quite handily. With a tapered plug are we not exerting similar outward pressure on the crack? I'm guessing that one needs to feel his way through the process and stop twisting at just the right time? Seems something soft like copper or brass would make a good plug down low in that area, if they make them. Just thinking out loud drinking coffee on a Sunday morning. I would be very pleased if I could execute repairs that looked like your photos! Thanks for sharing this knowledge.
 
Tubman,
I am just a long time car guy, and my buddy is a tool maker. We both have Flathead projects, and we pickup any engines and parts we can find, like most people on the Fordbarn.

Bob
 
There are plugs made that have a locking thread, and also thread inserts that lock, unlike common inserts. They are expensive.

Bob
 
GB SISSON said:
I have a 59ab in a tonner pickup I bought last winter. Also sat about 30 years according to PO's nephew. It was stuck, but not badly so I changed the oil, got it running and it ran real nice... Until I put a radiator and water in it. It quickly overflowed the oil pan with tan colored whipped pudding out the breather. I'm too busy with other projects right now, but I am trying to learn about cracked block repair. As quickly as the pan filled with water it may be cracked pan rails down deep. Would these plugs work in that area? On another note, I once ran a log splitter that was mounted on a truck's rear axle by the lug nuts. This was a large steel cone with a coarse spiral thread and a very sharp tip. The log round was thrown against the wedge which split the piece quite handily. With a tapered plug are we not exerting similar outward pressure on the crack? I'm guessing that one needs to feel his way through the process and stop twisting at just the right time? Seems something soft like copper or brass would make a good plug down low in that area, if they make them. Just thinking out loud drinking coffee on a Sunday morning. I would be very pleased if I could execute repairs that looked like your photos! Thanks for sharing this knowledge.
Click to expand...

Cast iron plugs expand and retract at the same rate as the cast iron block.
Copper or brass does not..
Bruce

Happy Easter to you all.
 
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