Using A Flap Disc For Removing Pitting And Paint From Lower Unit

[pilgrim52946]

It was suggested that I could use a flap disc for removing pitting and paint from the lower part of my outboard and lower unit using a couple of different grits, starting with a 80 to 120. And discs that are meant for aluminum grinding for sure. Anybody ever done this? Seems like it would work just not sure. I know everybody says you have to sand first, which of course is obvious. But what is the preferred method, orbital sander, block sander, belt sander, palm sander etc? To a certain degree I suppose it depends on where you are sanding on the unit (tight spaces) in order to get to bare metal. Or is there a better way of doing this,sand blasting it is too harsh as it will eat the aluminum. Soda blasting would be the way to go but it's too expensive. After I figure out what method I'll be using for sanding I intend to use JB Weld as a filler in the pitting and then regrinding it smooth before I apply the single stage self etching primer on.
By the way this motor is used in fresh water only no salt water.

 

[nwcove]

Re: Using A Flap Disc For Removing Pitting And Paint From Lower Unit

i would personally look around for someone that blasts with walnut shells. cheaper than soda, and not nearly as aggressive as sand. the flapwheel wont get into the pitting unless you remove alot of aluminum, and it will leave some nasty scratches! jmo

 

[V153]

Re: Using A Flap Disc For Removing Pitting And Paint From Lower Unit

Think I'd use a paint stripper before I went through all that. Note: Use one that's safe for aluminum ...

 

[5150abf]

Re: Using A Flap Disc For Removing Pitting And Paint From Lower Unit

Way way to heavy a grit, I would never ever touch anything I was painting with 80 grit, you use that on first coat ruff bondo never paint.

You want to start with 320 and you don't need to step down more than that, anything heavier than that and you will see the swirl marks and one of the biggest newbie paint mistakes is they think you have to remove all the old paint and you don't, if the old paint is still stuck to the engine it will be fine as a base for the new paint it just needs scuffed up.

Hit it with the 320, prime and then paint

If it is flaking off then in needs to be removed until you hit good paint and use the sand paper to feather the edge so it doesn't stick out when you paint.

You have to use and etching primer on aluminum though, available at any auto parts store for a couple bucks, if you don't your paint will start falling off inside a year, some recommend a vinegar wash but I wouldn't trust it with the primer only being a couple buck why not do it right.

And my last tip- a good paint job is 90% prep and 10%painting, I repainted my outboard and spent 20 hours sanding ect and maybe an hour painting, the difference between a $300 paint job and a $3000 pant job is about 100 hours, everything else is the same

 

[Mi duckdown]

Re: Using A Flap Disc For Removing Pitting And Paint From Lower Unit

Pilgrim. pics would help.