M104 magnesium valve cover restoration

[yao500e]

Hello M104 experts,

Is there a simple good way to fully restore stock M104 magnesium valve cover? These valve covers break and crack after a while while Aluminum would be LIFE LONG lasting.

Any info and experience here is great appreciated! thank you.

 

[JC220]

Get it vapour blasted which is gentle but removes all the old paint and corrosion. Then find a powdercoating place who has magnesium experience. For example the parts should be pre heated in the oven to de gas them before power coat application.

If you prefer paint finish for any reason then it's vapour blast followed by a suitable acid etch primer prior to paint.

The tricky part can be the safe removal and re installation of the "drip trays" in the inside of the cover. From memory I carefully blocked these off from debris getting in and also flushed them out before use. Vs risking fixings coming off inside the engine.

 

[yao500e]

Get it vapour blasted which is gentle but removes all the old paint and corrosion. Then find a powdercoating place who has magnesium experience. For example the parts should be pre heated in the oven to de gas them before power coat application.

If you prefer paint finish for any reason then it's vapour blast followed by a suitable acid etch primer prior to paint.

The tricky part can be the safe removal and re installation of the "drip trays" in the inside of the cover. From memory I carefully blocked these off from debris getting in and also flushed them out before use. Vs risking fixings coming off inside the engine.

really appreciate the information here. it sure does sound complicated though.
It seems like i got to be very careful about the inside of the cover as you stated.

 

[500AMM]

Painting Magnesium has the same challenge as Aluminium due to formation of surface oxides preventing satisfactory adhesion for the paint. The oxide is hard to remove and is often done mechanically with hard blasting or grinding, or chemically by an etching process. Both cases will give a rougher surface which may affect the final paint finish. Anodizing do also work very well on Magnesium, but has a limited choice of colours. However, anodizing will give better adhesion for painting on top of it.

As Joe @JC220 explained, the best way for a DIY is thorough degreasing, vapor blasting and etch primer prior to painting, or just do powdercoating. But in any case I would recommend using a paint shop familiar with such materials, because they have access to professional products much tougher than the man in the street can get. It's then important to find a paint shop having the process up running.

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As a comparison - in the subsea gas & oil business we use a number of materials on permanent installations, needing various types of coating for several reasons. One thing is corrosion which is controlled quite well with chatodic protection with anodes, but biofouling (growing) is also a huge challenge especially affecting friction between mating/moving surfaces exposed to seawater. Additionally does bare material give disturbing reflection when using ROVs with light & cameras. But the one thing common with an engine valve cover is the adhesion giving a durable painted surface.

 

[gerryvz]

Just remove all of the hardware on the underside of the valve cover. I just did this as show here:

Post in thread 'HOW-TO: M104 Top-End Rebuild (W463 G-Wagen G320)'
HOW-TO: M104 Top-End Rebuild (W463 G-Wagen G320) | G-Wagen Models