Powder Coat vs Paint vs Clean

[Jerry Scholder]

I've looked at so many posts about cleaning valve gasket covers and can't determine if powder coating them after sandblasting is a good idea or not. Some talk about it coming off with the high engine temperature; some say the hole dimensions will change, some say you have to sand areas to make gaskets adhere properly. I still have time to get the covers back if it's a bad idea. Anyone want to weigh in on this?

[JimLev]

The most important thing is to clean them with a good solvent after sand blasting, I use acetone then bake them at 450F to drive the oil out of the magnesium. You then need to clean them again to wash away the oil that migrated out of the magnesium.
Without getting the oil out even paint will start to come off.
Anybody that knows anything about powder coating will use hi temp tape to tape off the threads and plug holes that shouldn't have powder in them, those would be all the threaded holes.
I also tape off the area where the oil cap seals to the cover too.
No powder on any of the inside of the valve cover or in the groove where the gaskets go.

[bmwdirtracer]

I use Rustoleum Hammered Finish silver paint, either spray or brush on, for the M62 valve covers. I do a simple cleaning first, in the parts washer, then protect the threads with pieces of hose. This paint is damned-near miraculous, is immune to gas, oil, brake cleaner, etc, after it dries for 4 days. You can handle the part after 4 hours, and any recoating MUST be done within 4 hours. It's also particularly effective at hiding the poor, rough castings. It needs to be put on fairly wet, to ensure the intended all -over "fish-eye" effect.

Note that if you chip it, down the road, you can touch it up perfectly, with a brush, and won't be able to see any difference.

The silver is perfect for these valvecovers, and the black (really dark charcoal grey) is perfect for repainting engine blocks, and looks beautiful for over a decade.

[Jerry Scholder]

I use Rustoleum Hammered Finish silver paint, either spray or brush on, for the M62 valve covers. I do a simple cleaning first, in the parts washer, then protect the threads with pieces of hose. This paint is damned-near miraculous, is immune to gas, oil, brake cleaner, etc, after it dries for 4 days. You can handle the part after 4 hours, and any recoating MUST be done within 4 hours. It's also particularly effective at hiding the poor, rough castings. It needs to be put on fairly wet, to ensure the intended all -over "fish-eye" effect.

Note that if you chip it, down the road, you can touch it up perfectly, with a brush, and won't be able to see any difference.

The silver is perfect for these valvecovers, and the black (really dark charcoal grey) is perfect for repainting engine blocks, and looks beautiful for over a decade.

Thanks Chris for your input; really appreciate it.

- - - Updated - - -

The most important thing is to clean them with a good solvent after sand blasting, I use acetone then bake them at 450F to drive the oil out of the magnesium. You then need to clean them again to wash away the oil that migrated out of the magnesium.
Without getting the oil out even paint will start to come off.
Anybody that knows anything about powder coating will use hi temp tape to tape off the threads and plug holes that shouldn't have powder in them, those would be all the threaded holes.
I also tape off the area where the oil cap seals to the cover too.
No powder on any of the inside of the valve cover or in the groove where the gaskets go.

Thanks JimLev for your input; I plan to copy and send over to powder shop.

[JimLev]

Forget to mention as soon as the valve covers are cool enough to touch you can install them.

Thanks for the hammered finish info Chris. I've got some big suspension parts on the car I'm building that don't fit into my oven.

[bmwdirtracer]

You'll like it, I promise. For large items, buy the brush-on quart can, and buy disposable brushes. The stuff doesn't clean up easily, but damn, it's tough stuff. You will never see brush marks; the hammered / fish-eye finish takes care of that.

[Jerry Scholder]

Thanks for the replies. The powder coating shop did tape off the threads and plug holes. After the sandblasting, I would have thought the powder coating shop, if professional, would have done the necessary prep work to ensure the paint won't come off. The guy seemed to be knowledgeable of the environment it would be in but not sure if he knew they were Magnesium. No powder on inside and I'll double check the groove where the gaskets go.

- - - Updated - - -

Decision to sandblast and powder coat was made. Thanks.