Engine Cleaning Problem - uh oh
 

Hi guys...

I just made a boo boo and now i'm not sure what to do about it.

I buy and sell a lot of engines and the old crock pot trick has made me a lot of money... but today i put a saito 40 in there and left it on high (which i have done many times... its actually boiling or just under) for about 5 hours. Came home and pulled the lid and popped it out... i just run them under warm water... but this one had oxidized horribly. It's a dark dark grey now. Even the thrust washer which was machined is now almost black.

1st problem... i had forgot that i had thinned out my last batch and this was most likely 80% tap water run through a softener. Secondly, there was a homemade header... i think it was copper tubing or maybe brass. It's hard to tell. It also oxidized to a darker shade of brown.

Any metallurgists out there? What caused this? Did the brass/copper "bleed" off? Was it cause of the water?

Biggest question... can i restore the aluminum back to the light grey again? Or perhaps get it to a consistant dark grey? Right now i popped it back in.. hoping it will "complete" lol. I am thinking i might anodize the thing. How about powdercoating? It's a perfect engine that i just decreased in value .. ugggh. Any other suggestions?

Thanks

RE: Engine Cleaning Problem - uh oh
 

I'm no Metallurgist, but my thinking is that if you can't get it back to a satisfactory color/shade, simply find some high temp paint and give the engine a new look. Siato is renowned for their black Golden Knights, you just won't have the golden valve covers. Then again, I don't know the true condition of the inside of the engine, it may be shot all together.

Good Luck,

John

RE: Engine Cleaning Problem - uh oh
 

Don't know how it will run 'till you run it.

RE: Engine Cleaning Problem - uh oh
 

Guy who sold it thought the bearings were shot... oh no... just a little gummy. Inside is perfect, bearings, gears, piston/sleeve: all in beautiful shape. This is my first saito... nice engine. Just wish i hadn't bungled the case.

I did take a scouring pad to it and it scrubbed off the black ... but there's no way i'm gonna get it all... i'm wondering if Tarn-X will take off the oxidation? Anybody try a mini sandblaster?

RE: Engine Cleaning Problem - uh oh
 

I once bought a Saito 80 that was badly oxidised on the outside, but like new inside. I took it all apart, and packed the ccase and cylinder with rags and taped up all the openings. I had the bearings out also.

Then I bead blasted the entire exterior, and it looked like new. Use fine grade glass beads in a table top cabinet, you know the ones they sell for about $125 US or so?

If you buy a lot of old engines and fix them up, you will love the glass bead cabinet - and use it a lot, trust me. :)

AJC

PS that Saito is flying in one of my planes now, and no one even knows its not stock, looks like the diecast finish.

RE: Engine Cleaning Problem - uh oh
 

I did something similar to what A J suggests...I was given a Saito .80 that was in sad shape. I completely dis-assembled it, and bolted just the case, cyl. and backplate together and sand blasted it w/ fine sand at low air pressure. I got the finest silica sand the concrete contractor guys have, and use one of those siphon type guns that you stick the pick-up tube into a bucket of sand. It was something like 15-20 bucks (back a few years ago) got it from Harbor Freight as I recall. If you use as low an air press. as will siphon the sand, it works well, and will not erode the alum. if you use a "washing" or "dusting" motion...Came out looking as good as new!

RE: Engine Cleaning Problem - uh oh
 

Thanks Guys...
I thought i had a "Shortcut" solution today. I used some copper cleaner on a test piece of oxidized aluminum and it came out "clean" and so i then dunked the case in it. Welllll.... It's now a consistent shade of darker grey... lol! Maybe if i leave it in over night it will be a cool shade of black.

Anyway Guess i'm gonna invest in a blaster!

Thanks

RE: Engine Cleaning Problem - uh oh
 

I think you will like the blaster a lot. Very handy to have!

All the cleaners I know of are basic (like oven cleaner, most inductrial type cleaners, etc) and a base solution will allways turn the aluminum dark. Luckily if not left too long it is just on the surface, and you shoulnt have any trouble cleanign it off with a bead blast. Way easier than a wire brush!

AJC

RE: Engine Cleaning Problem - uh oh
 

Hey AJ... a little off topic but maybe some other's can use the info.. but i was looking at sandblasters. I assuming a small cabinet style? What's the difference between glass (beads)and tiny silica? Also what pressures do you use? and lastly, where do you buy the medium at? lol

Thanks

RE: Engine Cleaning Problem - uh oh
 

[X(] Don't breathe the silica-sand dust....bad news....[:o]

RE: Engine Cleaning Problem - uh oh
 

Most industrial supply places have the same cabinet (table top, about 24" wide, 16" tall and 20" deep) in various brand names, they are all made at the same factory in Taiwan I think... Comes with the gun, and a few nozzles.

I use the smallest nozzle of the three, and the pressure at 90 psi. The glass beads (or fine silica - same difference) was the finest I could buy, at the local supply place also, and it was a 10 or 20 pound bag, enough for many refills of the cabinet.

I modified mine a bit - first I taped up all the seams with aluminum duct tape to make it 100% airtight. Then, instead of having the chincy air filter that clogs up with the media (glass, sand, whatever) in a few minutes, I made an adapter to hook up my shop vac (large one) to the exhaust hole. I put a small spacer under the lid, so there is about a 1/16th space between the lid and the seal. Turn on the shop vac, and then blast away! The vac will cause a bit of negative pressure in the cabinet, and the air will rush into the cab under the lid glass, even when you are runnign the gun continuosly. It makes it a breeze to use, and no glass beads/sand get anywhere else but either stay in the cabinet or go into the vacuum.

AJC