How to Fix a Cracked Model B Block?

[rogeroadster]

I have a model B engine which I bought as a core to be rebuilt. It is a diamond block that has been re-sleeved back to standard bore and has bronze (or possibly copper) cam bearing inserts. It has not been magnafluxed or pressure tested or even cleaned yet. It has what looks very much like a crack running up from the water inlet boss. Because it is otherwise such a good candidate for re-build I thought I'd repair this crack by stop drilling the end of it, veeing it out and brazing it. Does anyone have any experience with this type of problem and could offer advice on fixing it?

[ursus]

Since that is not in a critical area, I would drill into the end of the crack to stop it from extending, fill the hole with J-B weld, and call it done. If that your only crack on this block I would say you are lucky. Most B-blocks, whether Ford made or diamond blocks are a crack waiting to happen.

[Karl]

You are lucky mine cracked in the floor of the valve chamber and I was advised it could not be repaired -Karl

[Duffy1]

ursus;

Interesting statement you make about B blocks are a crack waiting to happen . Care to share with us the basis for this statement . I have a B diamond engine as well as some other folks in our club . Sounds like we are riding around in a time bomb .

[Dave in MN]

I suggest metal stitching or drill the crack at the end, vee the crack and use slow set JB Weld. The slow set has much greater bonding power than the quick set. I use JB Weld to repair the more typical frost cracks and have yet to have one leak. I'd be concerned about heating the block for the brazing and have the heat cause the crack to travel. JMO.
Good luck with the repair.
www.durableperformance.net

[Drive Shaft Dave]

Sponsored Links (Register now to hide all advertisements)

I would do as Dave suggested. My block was repaired this way thirty years ago by my rebuilder and hasn't leaked a drop since. It was a freeze crack on the outside of the bottom of number four.

[Joe K]

Interesting statement you make about B blocks are a crack waiting to happen . Care to share with us the basis for this statement . I have a B diamond engine as well as some other folks in our club . Sounds like we are riding around in a time bomb .

Probably.

My Gordon Smith air compressor with a recycled "B" engine is one of those that cracked at the exhaust ports on cylinder 2 and 3. Fortunately for the GS conversion, the gasket covers both of these areas and there is no leaking of air into the cooling space or exhaust. It's almost as if the block were chosen for conversion to GS just on this failure/basis.

B blocks are noted for this. Not so much for a waterjacket crack like above. This almost looks like it might have been caused by lateral loading of the water inlet casting by it's location in the Harvester (or whatever.)

I'm with the others. Bolt 'er up after some stiching or gookum pucky if you must. Try superglue on the crack if you want to try the easy way out first. I wouldn't put heat to this area as the casting is extremely "constrained."

See if it leaks. If it doesn't then pray you have a cool block and you don't get exhaust port cracks.

And keep driving.

Joe K

[Pete]

It can be silver soldered but I would stitch it.
Most cracked B blocks have been abused. Once repaired they usually never have a problem again. We have them running on 100% nitro and they don't crack.

[Duffy1]

Pete ;

Thanks ,I will now sleep better tonight .

[Chris in CT]

Hi Roger,
I'm with those who have advised metalstitching the crack. Best mechanical repair for cast iron. Then seal the block... Happy motoring!

[luckyal]

I don't know if this makes sense but my mechanic used JB Weld and the metal stitching. That was 5 years ago and no problem since. I had the option of a very good replacement engine but I wanted to keep matching numbers and the original engine in the car.
Al

[J and M Machine]

Rodger: The best/permanent way to fix is metal stitching.
Model B blocks are thinner and are prone to cracks than Model A's just a fact. The first two photos show a typical crack on Model A/B blocks and the metal stitching. The third photo shows a B block spider web cracked on the deck due to stress/thinner casting.

Since you are in California it would be worth the trip to Lock and Stitch,located in Turlock,CA as they can fix the block for you. I would also recommend that they pressure test it as well. To be certain that no other cracks are in the block. Good luck.

http://www.jandm-machine.com/metalStitching.html

[Ice man]

Years ago I bought a near perfect 40 Buick Super 43000 miles, like new inside and out, but had a 13 in crack in the block. I veed the crack and filled it with JB Weld, sanded and painted it and its still good 50 yrs later. That crack is an easy. Iceman

[kelley's restoration]

jb weld is fine on an external crack
no real pressure there
but if you have axcess to stich it and its in your budget then go that way
tk

[rogeroadster]

Thanks guys these are great responses. I'm glad I posted the question before I just fired up the torch and went at it like I usually do.

[59mgaguy]

I've never used JB weld for sealing a outside crack in a block. But there is a first time. And I like JB. I used it on a lot of other stuff. For welding a outside crack you need to go slow. About an inch at a time. We had the block sitting on a working cast iron stove. After the inch was welded we let the stove go out. The next day weld another inch while on the working stove and let the stove go out. We did this till the crack was already weld shut. Slow but does the trick. If it cools down too fast it will crack.

[59mgaguy]

Sorry but it isn't an inch of welding. that's too long about 3/8th to 1/2 inch.

[glenn in camino]

I've stitched several blocks with overlapping, threaded, tapered pins. No problems.

[Bill in Al]

I had a B inserted and hardened seats put in several years ago.When I torqued the head bolts,in proper sequence,I heard a pop! Removed the head and found a crack between the intake and exhaust valves at # 3 cyl. SICK! Left it alone for four years and decided "to heck with it" and put it back together with a high comp.head. No water in the oil and no oil in the water after 1500 miles and it runs great! With a Mitchell O.D. It'll run 60+ easily and climb mountains like a goat. Don't write those old engines off without giving them a try first!I let this one sit up for years without enjoying it when I could have been having fun!

[hardtimes]

Originally Posted by rogeroadster

Thanks guys these are great responses. I'm glad I posted the question before I just fired up the torch and went at it like I usually do.

J&M gives good advice regarding Turlock company. You can also telephone them and they sell a kit so that you can do what they do as experts. The location/size of that crack, fortunately, is not critical area. Pinning/stitching is the best repair available and you can get the experience with their guidance to fix you own engine. Not cheap tho. Good luck!

[rogeroadster]

Originally Posted by hardtimes

J&M gives good advice regarding Turlock company. You can also telephone them and they sell a kit so that you can do what they do as experts. The location/size of that crack, fortunately, is not critical area. Pinning/stitching is the best repair available and you can get the experience with their guidance to fix you own engine. Not cheap tho. Good luck!

I will call them before I do anything. I'd like the satisfaction of fixing it my self so that kit sounds like a good idea.

[Tom Wesenberg]

I would JB Weld the crack.
If it ever failed then you could always go back and do the expensive pin job.

[dumb person]

Originally Posted by Tom Wesenberg

I would JB Weld the crack.
If it ever failed then you could always go back and do the expensive pin job.

This sounds sensible.