light sandblasting for engine corrosion?

[hestiaphoton]

Hi, I am new to everything here and to bmws (motorcycles! I have had 2002 and 1600 4 wheelers). My recent find was stored near salt water for a while and has a bit of corrosion on valve covers and engine box(?). plus paint thereon needs redoing. I don't want to do anything foolish at this point! Anyone done that? The sand blasting I mean, not the foolish part! Thanks, John

[Bob_Roller]

Need to use a less aggressive blasting media other than sand, aluminum is quite soft compared to steel or iron based metals .

Soda blasting is less aggressive, but I don't know if it will remove paint or heavy corrosion .

[nhmaf]

The critical thing is that sandblasting, or even soda blasting, on an engine which you are not intending to fully strip apart anyway needs to be done  with EXTREME caution, or avoided entirely.  Sand/abrasive grit particles can be devastating it they get inside and take up residence in bearings, oil galleys, etc.   Soda is almost as bad, it can also get into some tiny places.  There are numerous places that the particles - or the dust they create when they shatter against the engine case, etc. can get inside the engine and cause problems etc.  

If it were me, I'd take the painted things like that starter cover, valve covers, etc.  completely off and soda/media blast them separately.  Other 'gentler' media to consider instead of sand/garnet would be walnut shells, or soda.  After blasting, be sure to THOROUGHLY clean the blasted parts with (Water, if using soda) or other solvent.   Unless you're planning to completely take apart the engine as part of the process, I think I'd first try the 'manual' method of cleaning up the cases, cylinders, etc.   This involves a cleaner like Simple green, or even WD-40, or brake cleaner for the really tough grime, combined with NON-METALLIC scouring pads and elbow grease.  Truly, this is how most folks do it (unless fully dismantling the engine, etc.)   You can also find some of the non-metal scouring pad materials packaged for use with rotary tools - those would work well too.

Soda blasting can be very effective in cleaning of individual parts like carb bodies, fork lowers, wheels etc.  Monte Miller's Texas ghetto DIY soda blaster worked wonders on his R65 wheels and forks.   Just be extra careful about not blasting something like the engine - there are alot of little holes that grit being propelled by 100PSI can get into and thereafter into delicate internal places you really don't want abrasives to be.   You wouldn't use a pressure-washer (Water) on your engine, after all, would you?

[hestiaphoton]

Thanks for the advice...sounds to me like I was going to regret even light blasting with the engine intact. There is no reason for me to get inside there right now. I think I will try chemicals and elbow grease for now.

[clonmore1]

I was in a local BMW engine specialist recently sorting out the re-build of mine and saw an airhead engine that had been sand blasted, it looked terrible and the guy who has an excellent reputation for BMW's said he couldn't do a lot with it, it was ruined IMO.

My engine cases and all other relevant parts are going to be aqua blasted following complete strip down, I have had a couple of cases tested and the finish is amazing. It's gentle, but DOES leave residue, so heed nhmaf's advice.

My engine should be finished by Xmas and I will post some pics.

All the best

[steve hawkins]

I have also seen an airhead that had been sand balsted with the engine still in the frame!

It was then left over winter in an unheated but covered shed (damp)and it the engine/gearbox went very dark and dull, but in places, white an furry, i.e. it was even worse than when he started!   It looked awful.

I would never do it.  Scotchbrite pads and cleaning discs and a teflon spray base coating to protect the finish therafter.  Anything that wants painting - remove - as stated above.

Rev. Light.

[tvrla]

These things were sand blasted when new at the factory. But doing that now eliminates the patina, which I like. Things like the front cover, starter cover, valve covers, etc can look good sand blasted, but turn the pressure down to as low as 30 lbs.

I soda blasted an engine in the frame, and as already mentioned, the stuff gets into everything. But it's not that bad, just expect to spend time cleaning and don't be surprised to find white pockets of caked soda in the remotest places.

Most of the time I use aluminum cleaner and scotchbrite pads, wire brushes, etc to clean. If this is a rider, then every few months, do it again and after a while it'll look like new. Things are much easier a little at a time.

[hestiaphoton]

Thanks for saving me the heartache...looks like the tortoise wins again!

[Adrian]

I use an alloy whell acid spray and a very stiff nylon brush to clean up my wheels. I don't leave the acid spray on fo too long - maybe 5 minutes - before hosing it off and then maybe having a second go at the dirt. The look really good after a bit of muscle power. maybe the engine would come up the same. I've not tried it on the engine before so maybe now is the time so long as I'm careful with the acid getting into places I wouldn't want it to go.

[tvrla]

Here in the states we've got Eagle One Mag Wheel Cleaner that works very well on the cases and bare aluminum. It takes several applications with brushing/scotchbrite concurrently, but each successive time bites deeper. Aluminum is soft, but its corrosion is extremely hard and can take some time to penetrate.

[hestiaphoton]

I never thought of wheel cleaner! This site is great and you people are so helpful...glad I found you.  John

[tvrla]

There are two types of mag wheel cleaner - the one good for clear coated wheels (all mag wheel cleaner, they call it), and the stronger stuff that would damage clear coat.

Don't get the whimpy "all wheel cleaner", it's not what you want. The real deal after a few applications will foam up and you can see it working. Left on too long it'll turn the aluminum black. Not a big deal - another application removed in time will clear all that away.