Crack in engine block below exhaust manifold

ronp · #1 (**permalink**) 30-12-24, 05:30 PM

My 403 block exhibits a fore and aft crack in the area below the exhaust manifold. I understand this is part of a cooling jacket. Rumour has it that this can be successfully cold repaired. Could members share their experiences and repair process please.

RonP

Des · #2 (**permalink**) 31-12-24, 10:37 AM

On mine there is a thick metal plate shaped to fit snugly against the block face, a row of bolts around the periphery into drilled and threaded holes in face have secured it there since the late fifties.

David C · #3 (**permalink**) 31-12-24, 10:45 AM

I had an 85 series block successfully repaired many years ago. Much depends on the length of the crack and the thickness of the casting around the crack.
A search on the web for "metal stitching" should set you in the right direction. I was advised to have the block ceramic sealed once the repair was made.
Have a look at castingrepairs.com for pictures of the process.

HughMiller · #4 (**permalink**) 01-01-25, 10:18 PM

Cold stitching can work. If you look at the web guidance nowadays there are fancy tapered taps and plugs available which look really good.
Nearly 50 years ago, I did a similar crack in the low-tech DIY way, with brass rod and ordinary taps and dies (probably 2BA) with overlapping plugs set in with Locktite and peened over with a little hammer. Seems to have held up OK since then (though, to be fair, the car was in the garage for a very long time in the intervening years).

mikebro · #5 (**permalink**) 06-01-25, 05:22 PM

I had my 403 block stitched by Nick Hood of Surelock. Nick's company is now part of Castingrepairs.com. The car has only done a few miles since I had the work done, but so far so good. My repair was one of the biggest he had done on a Bristol 2 litre block - he had to cut out a large L shape, then make a repair section out of cast iron sheet, then stitch the repair panel in. He ceramic coated the whole cooling sstem by circulation after the repair was completed, then pressure tested. I posted this on this very forum some time ago, with photographs. The post title was "Water leak from block on 403 engine". General note - it really is worth searching previous posts!!