Bead blasting intake manifolds/valve covers?

[Stretch32]

I want to bead blast my intake manifolds to strip off the old paint and had a question. Will it hurt anything to bead blast the entire assembly to include the gasket surfaces? I was going to mask off these sealing surfaces but if it won't hurt anything to blast the entire part I'd rather do that. Has anybody else done this or can they provide some input.

Second, I was also going to bead blast the valve covers and was only planning to blast the outsides not the gasket surfaces or inside where it can come into contact with oil. Is this a problem or will I be ok doing this?

Thanks in advance,

Stretch

[304065]

The theory is that pieces of glass bead embed themselves in the soft aluminum or worse, magnesium and then come out to cause you trouble later. So the convention is to never blast parts that come into contact with the oil system.

On the manifolds, blast away, you can surface the gasket surfaces with a piece of 600 grit stuck with contact cement to a sheet of plate glass, or use a surface plate if you have one. Be careful however-- these old manifolds have corroded and the blasting process will remove more metal than you think.

[davep]

You might consider walnut shell, soda or CO2 as blasting media.

[gsjohnson]

Aren't some intakes magnesium? If so, I'd be very careful about media blasting magnesium versions. I had my 840 BMW magnesium valve covers ruined my powder coater who was prepping them by media blasting.

[Stretch32]

So would soda blasting be ok and not cause any of the side effects like bead or sand blasting? Would it be milder on the porous metal of the intake manifolds and valve covers?

Stretch

[rcnagel]

If you can find someone local who does tumbling, that is a great way to get a really good result. Sometimes is not always the media which can do the damage so much as the air pressure. High air pressure with media will expose voids were not visible before in magnesium and aluminum. Tumbling after media blasting will get rid of the flat appearance from the media. A person who is good at tumbling will tape off areas you don't want touched with Gorilla tape. Johns method on glass with sandpaper would still ultimately need to be done on mating or sealing surfaces.

[motogman]

I recently tried bead blasting my exhaust side valve covers. and was not thrilled with the results. it cleaned them up but wasn't the look I wanted. so for the intake side ( a 3.2 l btw) I used a red scotch bright pad. it was not all that much work and got the finish I was looking for. I will post some pics when I am on my computer this weekend.