Coating piston tops with a ceramic coating

[Merc 2.5]

I am leaving the skirts alone, since their skirt coating is pretty decent looking. I was disappointed a little in the fact that they didnt complete the coating all the way around and mask off around wrist pin, but hey, its one less thing I have to do. It is the crown that has me perplexed. They have a coating of sorts on the the 2 sides of the crown area without the flat area on the crown being coated. So, is that gloss gray coating a ceramic coating or what? And if so, leave it and just coat the flat area with more coating? thats what I am trying to figure out.

I just curious if u were doin skirts to. I couldn't tell ya whats on em. If u call promarine tech. They mite b able tell u sumthin

[Chaz]

Keef ,
The pistons you have are .. one step up from the standard.

Their skirt coating is good. No need to do the pin bore area, no thrust load there.

Looks like they did the crown , then did final machining to the top.

I wouldn't look to "lap' the coatings , just tape right up to the other blast and spray.

Might wanna paper and tape around the ring and skirt area ..to protect it from the blasting and coating ... The crown coating is heat reflective , not a dry film lube ..

[HStream1]

I have a question? Is the Skirt coating below the freshly machined Skirt surface? If so Its designed purpose is only 1/2 of what it was intended for.

As far as the Tops. I know exactly what that is. And its worthless as Tits on a Bore HOG!!!. I say that because exactly whats its purpose? The MFG coated the piston and then finished machining. Man It looks COOL and the Customer will be Impressed SMFH!!!

Place some High quality high adhesive tape on the coatings and see if it come off when the tape is yanked off. High Heat 500 deg tape is what I use. If it stays on then the substrate was properly prepped and the coating applied correctly. if not. Start from scratch.

Guys, I had finally got my coating from Techline earlier this week and I was excited this morning to get 'er done. But when I pulled the pistons out of the boxes I found this.............

Attachment 476265 If you look, you can see that the top is natural, but the deflector and opposite side is different. This is a pro marine piston. So my question is....what is that glossy gray on the top(sides)?

I did spray my adapter, and filler blocks..........but no pics today, I didnt get to cook them yet......just sprayed on and ran out of time. I will bake them monday morning. I cooked them for an hour(at 450) to outgas them before I sprayed them.

[keefallan]

Bud, the skirt machining is covered by their film. The machining goes halfway down to the wristpin bore and then stops. Both you and Chaz confirmed what I thought.........that they coated it(the top) and then finished machining the crown later. And that was my question even though I didnt ask it.........what good is the coating if it leaves 20-30 percent of the crown raw?

So Chaz and Bud, I genuinely thank you for your input. It was what i needed to know. I will check adhesion tomorrow at work and go from there.

Here's the bigger irony. I have had these pistons since the summer........before I had my block machined. I never pulled 'em out of the box till yesterday when I went to coat them...........DOH!! "I tell ya boy, you're about as shop as a bowlin' ball".......Foghorn Leghorn

[HStream1]

In looking at the picture it looks like what is shown of the skirt coating has to be below the machined skirt surface. I see what appears to be a 3/16" freshly machined band just under the lower ting land. Then the Freshly machined area down the Wrist pin area, then a 1/8" freshly machined band at the Skirts Base. So Is the Coated Skirt area on Both sides below the machined surfaces?

Attachment 476265

[keefallan]

In looking at the picture it looks like what is shown of the skirt coating has to be below the machined skirt surface. I see what appears to be a 3/16" freshly machined band just under the lower ting land. Then the Freshly machined area down the Wrist pin area, then a 1/8" freshly machined band at the Skirts Base. So Is the Coated Skirt area on Both sides below the machined surfaces?

Bud, the milling(machining) starts at the top of the piston side and continues halfway down. From there is just raw aluminum.....then they coated it.....1/2 in the ribbed area and 1/2 in the raw aluminum(from the wristpin to the bottom). Make sense to you?

[HStream1]

Milling??? That makes absolutely No sense. The areas im referring to are clearly machined by a lathe. Had the wrist pin areas been machined on a mill they would be flat vs a radius. I dont think youre following my questions. Look atn the Skirt coated area and the Freshly machined areas. Let me put it this way. Is the coated area on the Skirts and the Frshly machined areas on the Skirts on the Same plane? Or is one lower or higher then the other?

Bud, the milling(machining) starts at the top of the piston side and continues halfway down. From there is just raw aluminum.....then they coated it.....1/2 in the ribbed area and 1/2 in the raw aluminum(from the wristpin to the bottom). Make sense to you?

[InjectorService]

Took me a minute to realize what Bud was getting at too. What he wants to know is if the coated areas on the skirt are recessed, or the same height as the rest of the piston.

[HStream1]

Bingo!!! Because they either have a hell of a masker or they use a stencil to tape off the Freshly machined areas. Look at how perfect the coated corners are on the skirts.

Took me a minute to realize what Bud was getting at too. What he wants to know is if the coated areas on the skirt are recessed, or the same height as the rest of the piston.

[keefallan]

Bud, you have to understanding I have actually been milling most of the day.......so it was on my mind when I wrote the blog (as I ran out the door, pressed send and ran out the door kinda thing)

I Understand Now after re-reading what you were saying. To me, I have a machined portion and a raw aluminum portion on the piston side. The one half has zero machining marks........and that is what made me think the direction I did.....and I took the machining to be the upper half. OH well.

Bud, the coating is higher than the other and they had to use a stencil......aint no way a masker could do it that perfect. Sorry for the mix up.

[InjectorService]

So on that particular piston, it does not look like the coating extends right to the bottom of the skirt either. Would this have a negative affect? I would think that would still be a cylinder wall contact point, no?

[Chaz]

Whos old enough to remember "skirt buttons" .. ???

No , not at the prom ... like these --->



Wiseco , JE , Carrillo , CP , Advanced sleeve .. are all under one big tent now .

Wiseco started that " patch coating".. Ain't that cute ..

The bridge structure is pretty awesome .. I think Diamond piston started that .



To Wiseco's defense , they state that their pistons are to be measured minimum .500 up from the bottom and 90* from the pin.
Which tells me that there is quite a bit of "barrel taper" on both the top and bottom of their skirts .. this shot somewhat shows that .

But more importantly , speaks volumes about what Uncle BBQ said about the "quality of the job" . I know that my used pistons , even the ones I tortured , still have permanent remnant's of coating that you can see from across the shop. This slug looks like the coating "wiped right off" leaving an unprepared surface below.




After thinking about that crossflow "flathead Ford" a bit, and seeing what a fine job they have done ( coated pistons as a whole in the massed produced versions)
If it were me , I'd act like it's "just another nekkid piston" . Prep it the right way , coat it , bake it , and run the *(&^%&**(*( out of it ...

[keefallan]

When did they run skirt buttons Chaz? And for how long?


If I get the chance today, I am gonna blast me a piston or four..........but voting comes first today

[Chaz]

Flash in the pan .. circa early 1970's . Mostly fuel cars and Harley's .

[XP300]

Unique to say the least.