Engine cleaning before paint

[pAAt]

I have spent hours scraping my block off and I enjoyed every minute of it, which surprised me a bit. I have oven cleaner from the Dollar store and Simple green from another store. Tom Wesenberg, could you tell me the rest of the cleaning process or come down and show me how to do it ? P.S.- if you decide to come down, could you bring some plasti-gage and a variety of gauges, mics, shims, emery cloth, and misc. engine putting together tools ? Thanks your good friend, Pat

[Tom Wesenberg]

Be sure the oven cleaner has the good stuff in it that eats rust and paint. I spray it all over the outside of the block until it looks like it's covered with shaving cream, then stick it in a large plastic bag for a day. The next day I spray it again and use a parts cleaner brush to scrub it up, then rinse with hot water and blow dry quickly with my air compressor. Off hand I can't think of the ingredient in the good oven spray, but it's the same stuff as used in hot tanks for engine blocks.

Can't come down now because when the storm blew through yesterday it took out another large tree, so I have a mess to clean up.

[pAAt]

Tom, I wish I was able to breakaway from down here and come help you. Have some doctoring to do for the next few days. P.S. -I seem to have an extra April 1928 5 bearing cam engine block laying around now. Thanks, Pat

[BILL WILLIAMSON]

When I paint ANYTHING, I scrub it with T.S.P. It etches the surface to provide better adhesion. Ask ANY Painter!
Bill Shine

[tbirdtbird]

I'm with the advice above.
Here, we add a final step, and that is to apply Ospho (phosphoric acid) as a final etch.We use this on any steel we paint, including cast iron. We use a spray bottle to apply, and a scotch brite pad to rub it around. We dry it up with lint free towels, let it air dry or play a light flame from a propane torch to dry it. This will give you dull gray appearance to the surface. You have just chemically created a layer of Iron Phosphate, which is non-reactive. Any plain iron surface, cast or plain steel, is very reactive to atmospheric oxygen. This process is documented in the Handbook of Metals from the '40s. I can look up the page if anyone wants it. The process is termed 'passivation'. This is the best surface upon which to apply paint, because it is stable. We also do not use primer on cast; we do not want to insulate the block any, we want the heat out. We use direct-to-metal color coats made by Baril, Zolatone, etc
I have posted this info elsewhere only to have others tell me it cannot be used on cast iron. It is a good thing all the engine blocks I have painted for the last 40 years don't know that.

[pAAt]

Thanks Tbird, I'll google that and see what I can find. I'll get back to you, if I come up empty handed. Pat
P.S.- I'm back ! I found a pdf of vol 2 when I googled it. If you could get me a page number at a later date, because it looks to be a bit of a challenge to find it in there, I sure would appreciate it. Thanks, Pat

[tbirdtbird]

i'll dig up the page number tomorrow. in the meantime look under 'passivation'

different metals are passivated with different chemicals

In the meantime, check this out
https://en.wikipedia.org/wiki/Passivation_(chemistry)

I have a section of Model A frame I passivated 30 yrs ago, always stored inside, but no surface rust at all.
Of course, in practice, once we sandblast steel, then passivate it, then we apply epoxy primer right off.

I learned all this from a high-end Packard restorer 40 yrs ago

[Captndan]

I'm with the advice above.
Here, we add a final step, and that is to apply Ospho (phosphoric acid) as a final etch.We use this on any steel we paint, including cast iron. We use a spray bottle to apply, and a scotch brite pad to rub it around. We dry it up with lint free towels, let it air dry or play a light flame from a propane torch to dry it. This will give you dull gray appearance to the surface. You have just chemically created a layer of Iron Phosphate, which is non-reactive. Any plain iron surface, cast or plain steel, is very reactive to atmospheric oxygen. This process is documented in the Handbook of Metals from the '40s. I can look up the page if anyone wants it. The process is termed 'passivation'. This is the best surface upon which to apply paint, because it is stable. We also do not use primer on cast; we do not want to insulate the block any, we want the heat out. We use direct-to-metal color coats made by Baril, Zolatone, etc
I have posted this info elsewhere only to have others tell me it cannot be used on cast iron. It is a good thing all the engine blocks I have painted for the last 40 years don't know that.

I have been advocating the use of phosphoric acid for years. I have restored many old tractors which are mostly cast iron. Some have called me nuts but I still use Ospho on everything ferrous before paint. Save the primer for where it is really needed.

[tbirdtbird]

thanks for the backup!

[pAAt]

Tbird, I have a bare block. Would I mask off all gasket mating areas and seal off open pan/head areas. What kind of tape or material can I use to do this ? Thanks, Pat