Bonneville America Forums Forums Technical Forums General Tech Grey in engine case starting to blister

Is that rust under the powder coat? I assume it is, so should I be worried?

did you disconnect your oil filter? Just kidding.

where is the blistering? I don't think anybody's brought it up here before. Wouldn't the cases likely be aluminum?

The front main case just in front of the cylinders. Hard to the touch grey powder is still on it but its like a blister. Its bigger than last year. At first I thought it was an imperfection I just never noticed. I think its some type of rust. The cases are cast aluminum. I think they can rust.

Yea, oxidized aluminum, is loosely, a form of rust. Had to be a flaw present from the initial P. coat application. Metals generally do not oxidize in the absence of air. I would guess your bubble will keep getting bigger until you clean up the metal corrosion and reseal it. Got a die grinder or a Dremel?

I can grind it down but then I would have to pull the motor to get it powder coated again right?

Just repair the bad spot, if you can live with that. I would wait until major tear down time to re do the whole engine, but it's your call.

I believe a product called Alumna Hyde (gray) from Brownells gunsmithing supply would be a good patch and color match. web page

That's a bummer, Ron. I'm wondering if soda blasting the area in question might be a good way to prep it for new paint.

Didn't Grzegorz have to repaint his case when he did his complete teardown? But I thought that was because of damage from road salt or something.

I will try the little whole first and use a syringe to try to force WD inside. The more I look now it looks like its lifting and or oxidizing around the top of the right side cover too.

I remember Grzegorz did a new paint job. I figure its not the end of the world but I figure its gonna grow.

This bike is in Texas and in a garage! His garage mates don't seem to have anything like this going on.

I am going to Austin in a week. I think I will ask the Stealer if they ever saw it before.

This is exactly what it looks like but under the powder on the motor. here

Not the rust part the blisters. Taken from Grzegorz pics.

I will try the little whole first and use a syringe to try to force WD inside.
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If you inject a solvent under the lifted coating, it will seep under the surrounding powder coat and it will grow even faster. That would be akin to injecting growth hormone in a cancerous tumor. Inject some gray primer or do it right and prep the bad spot and recoat the cleaned metal with something that will seal it off from the atmosphere, thereby buying you time until you can do the whole she-bang. Just my opinion..K

I would sand off the loose coat with a dremel or something and touch it up with a paint that is as close a match as possible. I think that is the best way to stop it spreading any farther.

Ok, thanks, I will grind it off and use a motor type paint for the moment to see how that last.