MR upper and lower connected. Sand blast and paint or no

[chris0061]

I've got two MR out-drives complete and was thinking about hanging them and sand blasting and painting them. One has no corrosion at all the other does from being in a slip. Any thing I should cover, tape, or take off before I blast? thanks, Chris

 

[Alpheus]

Re: MR upper and lower connected. Sand blast and paint or no

You will never keep sand out of the seals and bearings. If you must go that route they should be 100% stripped down to bare case and stripped with glass media. If you wanted to strip them as one piece you can get them soda blasted. Sand and rotating assemblies don't mix...

 

[JustJason]

Re: MR upper and lower connected. Sand blast and paint or no

I guess you could tape up the yoke with a trash bag to make sure you keep the media out of that area. You'd just have to be extra carefull not to blast the bag.

It would be alot of work for minimal return though. The aluminum is soft so you'd have to use some black betty or more expensive meda to keep the housing from pitting.

Personally, I would just hit the blisters and any growth you have on it with a big old wire wheel brush on the end of a grinder. I have 5 inch cups on the end of a 40 year old skil brand grinder that would strip it much faster than blasting. After than, just clean it up. Prime, and paint.

 

[arks]

Re: MR upper and lower connected. Sand blast and paint or no

As the others say, sand basting may ultimately do more harm than good. It's not all that difficult to sand the cases using wire brushes and sandpaper. Proper preparation is the key to a good paint job, so make sure you use an aluminium primer that's compatible with your finish.
Also know that aluminium will start oxidizing IMMEDIATELY, so any bare spots must be primed within a few minutes for maximum adhesion.
Here's a shot of an MR drive I prepped myself and had a bodyshop paint with a 2 part enamel. I think it turned out great.

 

[havasuboatman]

Re: MR upper and lower connected. Sand blast and paint or no

You should NOT sand blast them. and Never sand blast the inside of any aluminum gear housing. The aluminum is to soft. There is no way to get all of the particals that are impregnated into the aluminum. But running the drive will loosen them up and destroy the drive.

 

[chris0061]

Re: MR upper and lower connected. Sand blast and paint or no

Thanks for all the great advise, I'm glad I ran this threw Iboats first. I'll have my alum primer in hand before I wire wheel and clean the outdrives. Thanks again. Chris. That mr drive looks auwsome.......

 

[mkast]

Re: MR upper and lower connected. Sand blast and paint or no

The aluminum is to soft. There is no way to get all of the particals that are impregnated into the aluminum.

Huh?
This isn't 1100 aluminum. Sand is not the ideal media to use, but it was common place in the military to sand blast the top of pistons used in radial engines.

 

[dakine]

Re: MR upper and lower connected. Sand blast and paint or no

You should NOT sand blast them. and Never sand blast the inside of any aluminum gear housing. The aluminum is to soft. There is no way to get all of the particals that are impregnated into the aluminum. But running the drive will loosen them up and destroy the drive.

Not in my experience.
I have bead blasted and painted many motorcycle engines.
You have to be fanatic about cleanup though.

If you have them blasted i would recommend glass beads which are less aggressive than quartz sand or slag.

After blast you must etch and convert aluminum if you want the paint to stick.

I use the DuPont 225s and 226s system before epoxy primer and single stage urethane paint.

http://pc.dupont.com/dpc/en/US/html/visitor/common/pdfs/b/product/dr/ChromaSystem/H-19290_225S.pdf

 

[Bronc Rider]

Re: MR upper and lower connected. Sand blast and paint or no

Thanks for all the great advise, I'm glad I ran this threw Iboats first. I'll have my alum primer in hand before I wire wheel and clean the outdrives. Thanks again. Chris. That mr drive looks auwsome.......

Alpha I, right? It sure does look awesome.

 

[arks]

Re: MR upper and lower connected. Sand blast and paint or no

No, Alpha 1's started in 1986 and the MR drive was used prior (1985 in my case).

Short story about that drive:
I bought it used but newly rebuilt from a good shop (with reciepts), so I thought it would be a good candidate for my boat. I spent a lot of time and effort doing all the prep work, paid for the premium paint job, paid for it to be installed on the boat, and after all that IT ONLY LASTED 4 MONTHS before breaking a gear. And NO, I'm not hard on my equipment. Stock 260 smallblock, no wake jumping.
The repair would've cost another 600 clams. I was tired of having outdrive problems (it wasn't my first), so I decided to bite the bullet and bought a brand new Alpha 1 (with transom assembly) from Mercruiser. Sure it was expensive, but it was stone reliable after that.....

 

[stevea661]

Re: MR upper and lower connected. Sand blast and paint or no

I blasted mine with a harbor frieght sand blaster and silica sand. masked the seals. I only blasted the out side, with the unit completly assembled. Used alodine and alumaprep, 2 part epoxy primer and matching paint. Turned out great and is holding up well. It was very time consuming, probably about 15 hours, and the material wasn't cheap either. If someone was going to charge ,me $500.00 for the job I did, I would have let them do it for that price.

 

[Bondo]

Re: MR upper and lower connected. Sand blast and paint or no

If someone was going to charge ,me $500.00 for the job I did, I would have let them do it for that price

Ayuh,... Every spring, before launch, I scuff the drive with a sctochbrite pad,...
Grab a rattlecan of Rustoleum Black, with a piece of cardboard in the other hand,...
And go to Shootin'....
I get the protection of paint for about a Buck, 2.98....
And, it takes a Whole 10 minutes....

 

[Fishermark]

Re: MR upper and lower connected. Sand blast and paint or no

I get the protection of paint for about a Buck, 2.98....
And, it takes a Whole 10 minutes....

Exactly. Plus, if you make it too pretty you get afraid to use it!

 

[Bondo]

Re: MR upper and lower connected. Sand blast and paint or no

Exactly. Plus, if you make it too pretty you get afraid to use it!

Ayuh,... Or if it's a Trailer boat,... Stolen....