Engine block surface prep

A

Ash

What I am best to do to prepare the engine block for epoxy? I plan to coat in epoxy and leave it at that, not looking for a show finish, just a tough durable and presentable finish. By sanding to get 80 grit scratches I'd have to smooth down the cast surface which I don't really want to do. What is recommend? Sorry to have to ask, I searched but did not come up with an answer.
 
Ideally you would want to start with a sand blasted or glass beaded surface on a casting. Being it is a casting it is already rough though and the cast surface should provide enough bite to hold the epoxy. Try and make sure you get it as clean as possible before spraying. You could also try a wire brush on a drill and go over the surface completely. This would give you some mechanical scratches without changing the look of the casting.
 
The block has recently been hot tanked and cleaned at the machine shop. But media blasting it further is no problem to do. I should have some Dawn washing liquid arrive this week from the US to give it a thorough clean.

I'm guessing a coarse/aggressive wire wheel be better to not polish the surface instead?
 
Ash said:
The block has recently been hot tanked and cleaned at the machine shop. But media blasting it further is no problem to do. I should have some Dawn washing liquid arrive this week from the US to give it a thorough clean.

I'm guessing a coarse/aggressive wire wheel be better to not polish the surface instead?
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When mine came back from hot tanking, I taped it off and sandblasted it bare.
 
If you decide to media blast the cast iron block, you might want to check out steel shot media. Its very small steel beads that will be easy to clean off, with no imbedding.
 
Abrasive blasting after degreasing is best. I quit having the machine shops shot blast my blocks because they weren't protecting the machined areas-main saddles, lifter bores, cam tunnel.... Blasting raises the surface height and messes up the tolerances some. Now I just have the shop do a bake and run it through their jet washer and then I do the final cleaning myself when I get it back. I've seen too many blocks come from the machine shop that were supposed to be clean and ready to assemble when in fact they weren't, and then if the shop has installed the cam bearings it makes it more difficult to clean, I bought a cam bearing tool so I can install them myself.
 
I've got 80 grit media here at the moment. But can look into steel shot media.

My shop mentioned several times to me, Bob, that the block still needed further cleaning. Which was reassuring to know that even though they had cleaned it, it needed further checking and they weren't taking short cuts.

My cam bearings are installed though. I better make sure I mask it up well.
 
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