Ducati Monster Forum

So I had to remove the stator side crankcase cover to address a small leak. After removing the bolts I noticed the Powdercoating I had done almost exactly 4 years ago was actually peeling away from the crankcase cover near the bolt holes. While removing the cover sure enough a piece of PC just broke off like dried paint. Also I noticed over time dimpling in my powdercoating that looks like cellulite. (See pics below)

Is this normal for Powder Coated engines due to the heat or is this a poor PC job? I dont want to go back to the same guy if this is due to poor craftmanship on his part.

Now I need to get both sides powder coated as the PC has faded over time and I cant have one side all freshly PC'd and the other one dull and faded.  :-\  This sucks removing the sight holes, bearings, etc. was a PITA !

(https://farm5.staticflickr.com/4367/36551188750_5e2f880d57_z.jpg) (https://flic.kr/p/XFUoZu)Untitled (https://flic.kr/p/XFUoZu) by ricknieto (https://www.flickr.com/photos/65036619@N04/), on Flickr

(https://farm5.staticflickr.com/4377/36113036714_beec1c61ed_z.jpg) (https://flic.kr/p/X2bKE3)Untitled (https://flic.kr/p/X2bKE3) by ricknieto (https://www.flickr.com/photos/65036619@N04/), on Flickr

and here's the PC Cellulite

(https://farm5.staticflickr.com/4353/36807606671_77846c7250_z.jpg) (https://flic.kr/p/Y5yB78)Untitled (https://flic.kr/p/Y5yB78) by ricknieto (https://www.flickr.com/photos/65036619@N04/), on Flickr

Here's what it looked like right after being powder coated.

(https://farm6.staticflickr.com/5448/9648487805_25988b1b90_o.jpg) (https://flic.kr/p/fGB2h2)Powder Coated Black! #ducati #ducatimonster (https://flic.kr/p/fGB2h2) by ricknieto (https://www.flickr.com/photos/65036619@N04/), on Flickr

Poor quality work.  Either poor oven cure time/temp or poor surface prep.

I wouldn't return to this vendor

I'd just about guarantee it's a prep issue.

To me, it looks like the aluminum is corroding under the pc, similar to the way a mag wheel will corrode under almost any coating if not treated with the correct chemicals. It can also be caused by handling with bare hands after blasting, or chemical treatment.

No surface prep. OE paint finish visible underneath the failed coating.

Insist that the piece undergo beadblasting and thorough degreasing before powdercoating and the finish will last. If not it won't, simple as that.

To the OP...

have you picked at that bubbling to see what's going on underneath?

When I was PC'ing stuff in my oven, a few parts turned out that way, and it was a mixture of improper temperature of the base material and poor surface prep. When I prepared the surface properly, I would still sometimes get parts that turned out that way and it was because the base metal temperature wasnt correct.

With aluminum, I found that if you had a large piece and did not bother to preheat it in the oven, then the temperature of the part took too long to reach the curing temp of the powder. While the powder will still  turn into a film, it does so at such a slow rate that it never adheres correctly.

So if you have a powder that cures in 20 minutes at 400 degrees, it isnt enough to put that part in the oven for 20 minutes at 400 degrees. You have to make sure the base metal reaches 400 degrees, and then you start your 20 minute count. Aluminum acts as a great heatsink, so it takes more time than steel to reach the correct temperature.

Eitherway, I wouldn't go back to the guy.

the strange thing is it didnt come out that way if you look at the before pic it's pristine. It morphed over time. I did pick at it and I'm no expert but it does seem like a shitty prep job.

My only explanation is that you have enough adhesion to hold the paint on intially, but throw in some heat cycling over the years and you might have some shear forces introduced in that paint to aluminum interface and fatigue the bond to failure.

Is there corrosion under the PC?

As others have said, poor quality work - most likely outgassing, which is trapped air in the rough casting of the stator cover - experienced coaters pre-bake a piece like this and shoot it hot. (One of my close friends owns a PC business.) I would give the original coater another chance to make it right, it's not an uncommon mistake and the work looked good otherwise. However, if he or she is one of the types who can't own a mistake, lie to your face and say it can't be done/won't guarantee it etc flip em the bird and go elsewhere.

Or, you can have the stator cover polished like I did and run the bare aluminum look. :) I specifically requested a brushed/patina look for mine -

https://photos.app.goo.gl/UrvkZw5yAMSqyuxU2