Crack in block

[Panda]

I have stripped the engine of my S4 L block and have noted a small crack between the head bolt hole and water jacket hole between no 2 and no 3 cylinders on the carb. side. It is definitely a crack as it runs slightly down the bolt hole and also the water jacket hole as well as horizontally between the two holes. A small line is noticeable on the head gasket.
There were no symptoms of a problem, no oil in water, or blow in head gasket. The engine was only pulled apart to check on low compression on no 1 cylinder, which turned out to be a valve problem.
Has anyone experienced this fault, and what would one advise?
Alan P.

[billwill]

I wonder if it can be brazed shut.

[rgh0]

Normally when brazing or cast iron welding a crack in a casting you need to drill out the root of the crack to stop it growing. Given the location of the crack this does not appear possible. Also it is generally hard to get a repair to work if its located near a highly stressed area such as the head bolt threads.

A possible repair would be to grind down from the top to open up the crack and round off the crack root. Then preheat the block and cast iron weld up the ground out section. then re-tap the head bolt threads and reface the top of the block. You also may need to line bore the block and cam tunnel if the heating and welding caused any slight movement of these bores. All of this would require a specialist cast iron repair place and not be cheap.

If you don't repair you may be able to run for sometime with some sealant around the bolt before the crack grows and you get a leak or head bolt pull out but it could fail the next time you reassemble the engine also.

I think its time to source another block

cheers
Rohan

[Elan45]

Alan,

If the crack is as small as I imagine, I would think you could drill out for a thread insert. I would not use a Heli-coil, as it is essentially a wound wire. But there are other brands of thread inserts which are solid steel with the original thread machined inside and a larger one outside. This may be enough to remove the crack. Check with your local bearing center.

Roger

[KevJ+2]

There's an L block on Ebay UK (Watford) item number is 200972798798 Good luck with your repairs.