winglift

My Feedback: (10)

I am rebuilding an engine after a crash and ended up buying parts for the rebuild. I wanted to clean the parts, which is a complete engine that was left to rust inside, and decided to use Dawn dishwashing soap. My mistake was that I thought by putting the disassembled engine parts in a crock pot with half Dawn and water would loosen up the rust and varnish. It did, but it turned the block, head, etcetera black. Any ideas how I could fix this? I had no idea that dishwashing soap would do this.

Campy

My Feedback: (1)

You might try the crockpot using antifreeze. The SHOULD have the engine looking like
brand new.

2 CAVEATS WITH THIS - 1. DO NOT USE THAT CROCKPOT FOR FOOD AGAIN (the antifreeze
will poison the food and you), and 2. USE THE CROCKPOT OUTSIDE (the fumes WILL do
a number on you if you use it inside).

Edwin

My Feedback: (2)

I think you're stuck with a black engine now. (Maybe its dark grey?). Even when using the antifreeze method in a crock pot, if you go too long or too hot, it will turn the aluminum a dark grey. I did that to a muffler I forgot about for a few days. Now I put the pot on a timer.
Edwin

Oberst

Hey, you could use it in a in-cowl airplane since it's dark, it won't show. Just kidding. I haven't heard about the antifreeze method... I was told if you left the body in carb cleaner too long it will turn black and that I'd be stuck with it. Next time have a timer set up so you won't leave it in the solution for too long. That's what I do. Maybe you should re-post this in the engine forum, I'm sure one of those guys can help you.


Pete

jlguru

I have recovered from this using a wire brush wheel on a bench grinder ... it will polish off the gray oxidization from the outside of the engine. A wire wheel chucked in a hand drill would be more cumbersome but probably work. Or, maybe a wire wheel in a Dremel tool?

Live long, and prosper
Jerry L. Gubka

Kimhoff

My Feedback: (22)

Clean it with as wire brush and paint silver.

aspeed

I used to work in a place where we did chromating.  First we dipped it in a hot tank of  I think.  just strong soap.  Then rinsed in cold water.  then a couple of minutes in etch which I think was nitric acid diluted a lot with water.  It would turn the aluminum black or grey, especially 6061 T6.  Then rinse in cold water.  It would make your fingers go black but you could wipe it mostly off unless it was left in too long (breaktime)  Then rinse and into deoxidizer  for a few more minutes.  This would take ALL the black off very well.  Then rinse and into the chromate tank for a very specific amount of time.  A few seconds for clear chromate and a couple of minutes for a gold chromate.  Then hot water rinse.  A motor would look nice in the gold colour.  I think  it would let the heat out better than some of the anodising coatings I have seen.  You could touch the alum. and your fingers would not turn black after.  Anyway,  the DEOXIDIZER would be the one to get a hold of.  No idea where to get it, or even if it is sold to the general public.  It might work for the black motor though, say after the etch and into the deoxidizer.  Maybe check into a coatings company in your area.  They would likely want money (who doesn't)  I would just leave it, tell everyone it is a special coating and charge them $20 to do theirs.  or study up on what the deoxidizer is made of. and try and get something similar.  I can't find out anymore.  I moved.  It would make you sneeze when you pulled the part out.

winglift

My Feedback: (10)

aspeed, Thanks for the info. I will look into the DEOXIDIZER otherwise I will just have to rebuild it as is.

jaka

Hi!
A friend of mine did the same years ago the night before a pylon race...The engine (K&B 3,5cc) was beond repair. Piston to cylinder fit was toltally lost![]

aspeed

If you are deoxidizing alum. all of the parts should be stripped off that aren't alum.  I tried the crock pot antifreeze on a garage sale Supertiger .40 that was really black.  The aluminum cleaned up fairly good, but the piston/liner didn't change much, which was the reason I wanted to do it.  I still had to go and take it all apart and scrub the piston cyl. with acetone and scotchbrite to look good. The rear bearing cage was separated, likely was just that way when I got it.  Maybe the previous post K&B 3.5 was already worn out and the compression was all due to the varnish?  I didn't think dishwashing soap would remove metal.

winglift

My Feedback: (10)

I had already used a wire brush on it for several minutes and little change. After reading your previous post, I decided to soak the pieces in the sink with hot water and Oxiclean then when I used the wire brush, they seemed to clean up nicely and noticed that the water/Oxiclean got black. I don't know if the Oxiclean did it, but I have the engine looking pretty good now. I plan to use a scotchbrite pad to finish it. I don't have the nerve to try that solution in a crockpot, but curious about it.

kenh3497

I have some stuff here that will turn aluminum blacker than the inside of a coffin on a moonless night I've done it on purpose on a couple of engines. The theory is .... The black gives up heat faster than the bare aluminum. Never had a temp gauge to test it though. It is a bit fragile until it "dries" after treating. I've soaked it in WD40 and then baked it to set the color and it seems to hold OK. The process is a cousin to bluing a gun.

aspeed

I was always under the impression that a coating traps the heat in alum. at least.  I believe a sandblasted finish acts as miniature fins and covering them would slow the escape.  Anodizing IMHO is one of these.  It is more of a decorative finish.  It is easier to wipe clean and looks good.  It may be an advantage to keep heat in on a motor, say on a head to keep the plug lit on idle, but I think a natural finish would be more desireable in most cases with a glow motor, and muffler at least.  Having said all of that , it probably isn't a measurable difference.  I think an car radiator gives off the heat better from the black coating mostly because of the metal powder mixed in with it. It is supposed to be like a metal flake paint.  I still like the look of my LA .15 and .40 over the natural finish but use the natural ones for racing just in case.  (I never win either way though)

Wayne Miller

Hi,

If you ever use the crock pot / antifreeze method for cleaning aluminum engines, make sure you buy the new antifreeze that is designed for specifically for aluminum car engines otherwise it will turn the engine black.

Fly4Fun,

Wayne

kenh3497

The process I was referring to is not a "coating" like paint. It simply changes the color of the aluminum. Like the "blue" on a gun. Black is supposed to be a better color to radiate heat from........ Like I said, never tested the theory, but I liked the look of the black motor.

I agree a lightly blasted surface give much more surface area to radiate heat from.

aspeed

I think black soaks up the external heat (as does dark green) which would likely add to the heat if anything.  The black dune buggy motors do look pretty good though, it likely is no benefit, maybe keeps the heat up at idle, I would think.  I think an experiment would have to be done, and it wouldn't be measurable.  I will have to think of an application for the WD 40 treatment.  I think I got one of those heat sensor things somewhere. Probably put in in an oven for a specific amount of time and check the temp. plain and coloured on a heatsink would be a good test.  Oh Hi Wayne.

LesUyeda

"I think black soaks up the external heat (as does dark green) which would likely add to the heat if anything"

I don't think so; I think it radiates the heat better than any other color. My recollect is that all "heat sinks" for transistors, etc., etc., etc. are flat black (and auto radiators).

Les

aspeed

I won't make a judgement until I could see some experiments done, Some of the new Streetrod radiators are natural alum. finish, as well as some racing ones. This could be for economic reasons or performance reasons. Alum. would have to ideally be chromated before painting for the paint to stick. I am sure automotive people have spent the money to experiment. They have money to burn to get the last 1/10% efficiency, but also to save 1/10 of a penny to save on production costs. We made lots of heat sinks at work (military and commercial) that were yellow chromated and clear chromated as well as black. (black oxide? or anodizing) Then there are black solar 'collectors' to absorb heat for swimming pools etc. Some insulating foam for homes has reflective foil on the outside to reflect heat back outside in the summer to keep the heat out as well, and they have sheathing and siding over that so there wouldn't even be any sun on to affect it. As model motors go, it likely makes no measurable difference. I think if you want a black motor go for it. Different materials as a base metal would make more gains.(nylon venturi for cooling, brass head buttons to expand more and tighten up on the cyl. as well as maybe ceramic or plastic to hold the heat in better etc.)

LesUyeda

"Streetrod radiators are natural alum."

:-))))))))))))))

Signs of the times; in MY day, the only thing radiators were made out of were brass, and sometimes a little copper.

Les

Charlie P.

Bcause of the laws of thermodynamics: if a black object is a good absorber of heat it must also be a good radiator of heat. In practice I don't think toning an engine to dark oxidation would make much difference. It's a long way from a truly black surface.

jaka

Hi!
The piston was all white from oxidation and that white stuff could be wiped off...Gues how the piston to cylinder fit fit was in that ABC engine (K&B 3,5cc) after that..!?

kenh3497

The "chemical" I was using comes from Birchwood Casey. They have several varieties for coloring different metals. It works pretty good although the surface have to be squeaky clean for best results.

I checked the web site and they have a "new" process (imagine that!!)more involved that what I had done in the past. Here is the link. Certainly doable by anybody if the quantity you have to purchase are not outrageous.

http://www.birchwoodcasey.com/news/5821.html

OK more info. I thought I had a one step process and I found it here; http://www.birchwoodcasey.com/antiquing/options.html Scroll down to the bottom of the page, it's the ALUMA BLACKĀ® A15 IMMERSION. I have a quart but the smallest now is 1 gallon @ $128. It you had a few guys that wanted to do this it would be very affordable.

Ken

LesUyeda

"Isn''t half full and half empty the same thing???????"

Depends on whether your an optimist or a pesimest:-)))))))))))))))))

Les

kenh3497

I can't make up my mind either way, so I don't know what I am..... Maybe a realist?????? In any case I know for sure, I'm some kind of an "est" or "ist" depending on what it is.

LesUyeda

From the engineering stand point; the vessel is too large for the application:-))))))))))))

Les