Help! How to fix crack in engine block

[ingrid75]

How old is this engine? If it has a lot of hours on it a problem like this could be just the beginning of other similar problems. Mickey Mouse repairs with epoxy are just emergency measures to get the boat to a safe place for proper repairs. To properly repair this engine will be expensive and you would never know if there was another hole waiting to reveal itself. Don't throw good money away. Bite the bullet and buy a new engine. You will sleep better at night.

[Snowpetrel]

As a temporary/semipermenant fix I would maybe try using those four mounting bolts below the leak to bolt an oversized plate of steel over the hole. Then you can try a few options such as epoxy or some sort of gasket or O ring seal with the plate to compress it onto the leak, so you aren't relying 100% on the glue to stick.

You might even be able to tap the block (or find an existing bolt) so that whole area can be plated over.

Much better than trying to weld cast iron. Its a prick of a stuff to weld, especially if its rusty and contaminated. I welded up an exhaust mixer. Preheated it, peened it, but still had issues with cracking. Ended up working ok, but I chased the crack all around the place for a few hours. I would avoid it at all costs.

There are some neat crack repair systems involving drilling and tapping such as the lock stich system http://www.locknstitch.com/index.html. That would be another avenue.

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[el31415]

Muggy weld check this video almost same location as you engine

Welding Cast Iron

[coastalexplorer]

Historically Cast iron castings were heated in a forge and welded while hot. As already stated special welding rods have been developed to make this less necessary. Yes I have heard of the concept of peening to relieve stress between passes. but the idea is to have the casting cool very slowly over time to give enough time for the stresses to relieve.

There was a time when new iron castings would be poured on a Friday night and shaken out on a Monday morning having had the whole weekend to cool in the sand mould. In modern times this is seldom done. Although for certain metal alloys; foundry's do far more heat treating than they used to. How ever in the case of de-stressing welded cast iron repairs. The simplest and most effective way to assimilate the old Idea of leaving the casting in the sand is to bury it in a bucket of Lime. Available from the gardening store. This is far simpler and more effective than Asbestos blankets. where are you going to get those from anyway?

As for the report that oil is leaking from the damage, I would agree that this suggests a whole new level of complexity. Certainly removing the engine block from the vessel would seem to be the best course of action. IF upon inspection plugging the hole mechanically seems viable. The use of a tapered pipe tap would seem to be the logical way to go: Providing as already mentioned it can be determined that it is possible to effectively flush out the swarf from the drilling and tapping operation.

[tkeithlu]

How very clear and informative. I've learned something today. I guess I should assume progress has been made, even in as ancient a matter as cast iron, in the many years since I last took a materials science course. Thank you.