Can this flathead be saved?

3

39wagon

Junior Member
I have a good running '39 flathead that has developed a rust-through hole in the water jacket just below the exhaust manifold's lower bolt on the rear-most outlet. I've read on the Model T site about using the original JB Weld for this kind of problem and also about using a High Temp Belzona epoxy on the Cummins diesel site for patching in these kinds of situations. Do any of the Early V8 community have any PERSONALLY PROVEN solutions to fix these kinds of problems that does not involve using a torch? It's a nice engine and I'd really like to save it. Thanks.
 
39wagon said:
I have a good running '39 flathead that has developed a rust-through hole in the water jacket just below the exhaust manifold's lower bolt on the rear-most outlet. I've read on the Model T site about using the original JB Weld for this kind of problem and also about using a High Temp Belzona epoxy on the Cummins diesel site for patching in these kinds of situations. Do any of the Early V8 community have any PERSONALLY PROVEN solutions to fix these kinds of problems that does not involve using a torch? It's a nice engine and I'd really like to save it. Thanks.
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Yes. Similar issue on a 59L block. Used Belzona 1212 epoxy. My rebuilder made some spatula like tools to get the epoxy inside the water jacket in the block first and then let that cure. Did another pass over the area on the outside as well.

Belzona is expensive, but #1212 is designed to be used in less than surgically cleaned areas which your block will be.

Look up Belzona. They are the only epoxy approved to be used on Caterpillar motors, so it's got to be good stuff. It can be tough to get a hold someone at Belzona, but they have regional field reps that will sell it to you.

The guy I dealt with offered to help with repair. LOL!
 
Make a patch larger than the rusted out area, large enough so you can drill a couple of holes where the metal is still thick enough to drill through the patch and thread the holes in the block so you can tap them and have two bolts going through the patch screw into them.
Pack a quarter inch of RTV or the RIGHT STUFF on the patch before you bolt it on.
If you don’t use a pressure radiator cap you can make a patch with sheet metal and just let the RTV dry a couple of days and you won’t need to bolt the patch on.
I’ve done that on motors that had thrown a rod and broke out the side of the block.
What Tim says sounds good too. I’d make sure it was real dry and after puting the stuff on the inside I’d screw some coarse screws into the stuff before it dries. Leave a half inch with the screw heads sticking out for something more for the outside epoxy to hold on to.
 
Actually if you just fill that part of the water jacket with epoxy it may be ok.
I’ve seen them so full of rust that no water got into the lower area and it motored along just fine.
 
Helped a friend do this same repair on his 40 engine using JB Weld and a piece of sheet copper. That was more than 20 years ago. Still running good.
 
If it is like a pin hole or deep pit, is there enough good metal around it for it to be drilled and tapped for the smallest pipe thread that would get the job done? 1/8 or 1/4 NPT??
 
Thanks for all the good ideas. I think I'll do a bit more research on the heat/water properties of JB Weld as well as contact the Belzona people for the same information and then form a plan of attack. The close proximity to the exhaust manifold is my main concern. Anyway, I'll let you know what I come up with and how it works. Again, thanks for all the help.
 
About 10 years ago I bought a 50 Ford in Tampa FL that had been stored for 15 years 14 hours from me. Flew down there with the intentions of getting it running in the sellers driveway and driving it home. After we got it running water was seeping from the block due to a 4” crack by a water jacket. I used the rental car, went to the local auto zone and bought some quick setting JB weld, and a bondo spreader, and a can of brake cleaner. Cleaned it well, spread a layer of JB weld insuring to fill the crack. We went and had lunch while the JB WELD was curing then drive it 14 hours home plus a additional 4200 miles after before I sold it with no issues to my redneck repair.
It was a crack starting 1/4” from the exhaust manifold which had me concerned
 
About 8 yrs ago my mechanic did this with my 1912 Buick. Water wasnt let out for the winter and a few hairline cracks......


he took a dremel, carved a v into the crack and used JB weld.
car has been fine since and now sports antifreeze for the winters. Not a lot of pressure in these areas.
 
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