Valve covers vapor stripped

[Mpow-wow]

I was surprised at how rough and cracked/flaky the castings are. I assume this is normal?

[DrFerry]

Originally Posted by Mpow-wow

I was surprised at how rough and cracked/flaky the castings are. I assume this is normal?

The quality of the casting in the photo doesn't look too good to me. I'm assuming (hoping) most or all of the metal flakes are all being caught by the oil filter... The S65 valve covers are magnesium if I recall correctly. Perhaps casting magnesium is tricky but quality control should surely have been better for these parts IMO.

[Mpow-wow]

Originally Posted by DrFerry

The quality of the casting in the photo doesn't look too good to me. I'm assuming (hoping) most or all of the metal flakes are all being caught by the oil filter... The S65 valve covers are magnesium if I recall correctly. Perhaps casting magnesium is tricky but quality control should surely have been better for these parts IMO.

The inside is decent, the outside many areas don't look so great. No flaking off, but definitely surface cracks and a lot of pitting.

Either way, still getting them powder coated blue or orange and going to send it. 👍🏻

[nycplumber]

Idk about that. I had mine powder coated but went to a place that work with magnesium all the time. You shouldn't strip these with chemicals. Soda blasting very carefully is the safest way (definitely dont want to sand blast). After they were blasted they were hit with a chromate process and looked immaculate. To my uneducated eye that looks like it was damaged by whatever stripped stripping product was used. I believe that's corrosion. Definitely get an experienced professional to look at them before coating

[Mpow-wow]

Originally Posted by nycplumber

Idk about that. I had mine powder coated but went to a place that work with magnesium all the time. You shouldn't strip these with chemicals. Soda blasting very carefully is the safest way (definitely dont want to sand blast). After they were blasted they were hit with a chromate process and looked immaculate. To my uneducated eye that looks like it was damaged by whatever stripped stripping product was used. I believe that's corrosion. Definitely get an experienced professional to look at them before coating

Originally Posted by nycplumber

Idk about that. I had mine powder coated but went to a place that work with magnesium all the time. You shouldn't strip these with chemicals. Soda blasting very carefully is the safest way (definitely dont want to sand blast). After they were blasted they were hit with a chromate process and looked immaculate. To my uneducated eye that looks like it was damaged by whatever stripped stripping product was used. I believe that's corrosion. Definitely get an experienced professional to look at them before coating

Thanks, was stripped by vapor blasting. I asked and said no sand media, he said he's done $50,000 porsches motors. 🤷

Obviously I don't have much of an idea of what the condition of the castings was underneath, but kinda shocked actually.

Wasn't sure it it was kinda normal or not.

[nycplumber]

Porsche has used magnesium on their valve covers so I'm sure he is familiar working with it. I'm uneducated about this stuff and only know a little bit about it but it does look rather rough. What do I know though lol.

[Mpow-wow]

Here's a far away photo.

[KawBoy]

They are just like that. Sad, but true.

[Mpow-wow]

Originally Posted by KawBoy

They are just like that. Sad, but true.

Thanks, I guess that makes me feel better, I guess. 😂

Either way, I'm running them to powder co today. 👍🏻

[Redd]

Looks pretty standard for magnesium. They are fragile, hard to work with, and don't last very long. But hey, #BecauseRaceCar.

[Zero Signal]

Mine looked the same way

[Vedubin01]

Originally Posted by Mpow-wow

I was surprised at how rough and cracked/flaky the castings are. I assume this is normal?

Yup typical! I spend several hours sanding them down before powder coating. That way they come out looking much smoother. Powder coating is much thinner than that 2 part epoxy they use to cover up that casting

[Mpow-wow]

Makes me feel better, mine aren't going to win any shows (no sanding) but they be 5 footers! 😎

This is the color I'm going with.

[deansbimmer]

It's not a defect or the fault of the vapor hone guy, it's how magnesium breaks down over the years. Oxidation is very aggressive with Mg. These are 10-15 year old parts by now.

Magnesium doesn't respond well to vapor honing. It's not like aluminum. This metal needs to be treated, plated or coated and sealed from oxygen so it doesn't degrade.

[Mpow-wow]

Originally Posted by deansbimmer

It's not a defect or the fault of the vapor hone guy, it's how magnesium breaks down over the years. Oxidation is very aggressive with Mg. These are 10-15 year old parts by now.

Magnesium doesn't respond well to vapor honing. It's not like aluminum. This metal needs to be treated, plated or coated and sealed from oxygen so it doesn't degrade.

Thank you! I was having some doubt about "The vapor hone guy" now I won't.

The "powder coat guy" is going to pre-bake, should I expect that the finish might not be as strong/less adhesion? I'm not to worried about it (if it don't leak). I'm replacing everything and will replace covers next time.

Thanks for the info Deans Bimmer (was my dads name also).👍🏻

[deansbimmer]

Any engine part should be outgassed and baked before final blasting and coating. You also need to grind down and smooth those surface defects before further coating prep- especially around the bolt pockets and sealing grooves. It's tedious but necessary. We do a lot of these, the prep is the worst part.

[Mpow-wow]

Originally Posted by deansbimmer

Any engine part should be outgassed and baked before final blasting and coating. You also need to grind down and smooth those surface defects before further coating prep- especially around the bolt pockets and sealing grooves. It's tedious but necessary. We do a lot of these, the prep is the worst part.

We'll definitely won't win any awards then. I guess I should have sent them to you, but trying to wrap this thing up this weekend. Patience definitely isn't my virtue (on finishes), I'm ansi to drive. 😀
truck is getting boring.


You hiring machinists? 😂

[Mpow-wow]

Haven't seen in person yet, but look decent.

[deansbimmer]

Great color choice, looks good!

[Mpow-wow]

Thanks Dean.

[nycplumber]

Looks amazing. Very happy I was wrong!