Engine Block Prep

BBPanel

BBPanel

Promoted Users
Have engine long block that was put together several years ago and was not painted at the time. Now has minor surface rust. Is mechanically removing the rust the best solution or can one use Phosphoric acid to do that? My concern with the acid is keeping it and the rinsing phase out of the internals.

Once I have cleaned the block by whatever method and shoot epoxy what is the window for top-coating, 7 days? Thanks. -Bob
 
Sanding it would be safer if you are concerned about contamination. Black cookie discs and the green plastic bristle 3M discs would work well. After doing that if you plan to epoxy go over everything lightly with some 80 grit by hand. Obviously you want to mask everything that could get contaminated.
 
www.zoro.com

Weiler Knot Wire End Wire Brush, Steel, 3/4" 90192 | Zoro

Order Weiler Knot Wire End Wire Brush, Steel, 3/4", 90192 at Zoro.com. Great prices & free shipping on orders over $50 when you sign in or sign up for an account.
www.zoro.com www.zoro.com

these worked well for me,You can get into little areas that a flat disc can't get into... ,used them on a die grinder ...also my local ACE had them ....
 
The question I always have is how does the basecoat clearcoat stuff survive on engines? I see all the shows doing base and clear on the blocks to have them ready for the reveal. I know we painted some clear on brand new aluminum heads and it was yellow in a week.
 
I don't know about base/clear but in the past I always used etching primer and single stage urethane and I never had one fail or dis-color. I have also seen complaints about clear/colorless on aluminum yellowing also - perhaps it has something to do with no pigments?
 
Looks like the consensus to my OP is to remove the rust mechanically. In the past I always dealt with clean parts (no rust) from the machinist, wipe it down with de-greaser and shoot. My guess is its going to be a lot of work and I will have learned my lesson the hard way.
 
Last edited:
I have always washed the engine after assembly, dry, then paint. But one time I had to remove the oil pan after painting and was surprised to find water in the pan, so make sure you do a thorough job of masking. Scrubbing the block with Ospho is good, it won't take long to clean it up. Just so everyone knows, phosphoric acid (Ospho) eats cast iron much quicker than steel, I guess its the open pores of cast iron so don't allow anything cast iron to soak in the acid.
 
You must log in or register to reply here.
Back
Top