I need a new valve cover. I got a used one that has minimal wear all things considered. I plan on having it soda blasted to clean it to bare aluminum, but aside from that I don't know if it should be painted, anodized, or even hydrographed (hydrographicsinc.com). From the sound of it hydro graphing is a solid bet, but is going to run about $125 without shipping.

I painted my old valve cover once upon a time ago after it had been sand blasted and I used paint from the auto parts store for valve covers. It has since begun to severely bubble, so I'd prefer to pay someone to do a proper job. I'd like this to be the last time I have to worry about the condition of the valve cover for the next two decades.

 

The valve cover is magnesium, not aluminium. For some bizarre reason Jaguar saw wisdom in dropping alum. after the XJ40 (I believe mag. is lighter weight). Sadly the XJ40 cover doesn't fit the X300 head.

Others may come in with more informed comment, but I understand that mag. doesn't take too kindly to "conventional" painting - anyway, whoever is to professionally finish it for you needs to know they are dealing with mag. and not alum. Like you, I'd like to find the best solution for refinishing the mag. cover!

 

Did you use primer first and allow it to cure properly? I used Dupli-Color 500* engine primer and enamel and put the cover in the sun for a couple of days between the prime and finish coats. It's holding up well.
There were some blisters in the original finish which I ground out and filled with JB Weld.

 

Here's some info on prepping magnesium control surfaces on airplanes that might be useful:

Prep Magnesium for Painting


Any good high-temperature primer and paint intended for engines should work well as long as you prep the surfaces properly.

Cheers,

Don

 

You could always just polish it, like I did with mine...

 

That IS a neat engine bay!

Graham

 

How did you polish all of the covers like that?

 

Every metal component was striped of paint and hand polished - mainly in situe apart from the cam cover which I bought a 2nd hand one and polished it separately.

Intake manifold was the worst to do, due to its shape and accessibility.

 

I just did some sanding and grinding then used High Heat Enamel, I've since done the same on my heat shield.

 

I love the idea of polishing it. What did you use to get such a strong shine? No issues with the enamel bubbling? It'd be a good bit cheaper to polish it than paint it over having it Hydro graphed. I just want something that will last for the next 300,000 miles and 30 years.

 

I had my cover and supercharger ducting soda blasted and powder coated. I then painted my coil cover and fuel rail same colour as the body of my xjr.

 

What all did you have soda blasted with regards to the underside? Or rather, how much of the underside did you have soda blasted? All of it, or just the groves where the seals sit.

 

The actual media used to blast it was of a silica type. Only the top and sides were done. There was still a lot of clean up necessary to rid the inside of the cover from all the residual leftover. There was some flaking on the inside of the cover so I did hand sand it a bit. Once everything was buttoned back up I drive it for some amount of kilometres then gave it a cheap oil change to wash any fine particles which may have been leftover mostly for piece of mind although I saw no debris.




After Silica blasting and before powder coating coating

 

Did you powder coat the underside or leave it bare magnesium?

 

I'm betting he left it bare. I wouldn't want a painted or coated surface within the "internals" of the motor.

 

I tend to agree, but was curious.

.

 

Hi, Al,

I left the under-side untouched except for giving a quick
hand-sanding on some protrusions I felt might eventually
pose a falling-off risk. Again, I didn't sand the whole inside,
just knocked off a few high spots and used air to give it a
really good cleaning and a mineral wipe down inside the cover.

Feel free to ask any other questions regarding this process.

 

Beautiful, and very interesting approach dfieldsend! You mentioned that you didn't do the 2nd hand cam cover in situe. Can you explain the process you used for stripping, cleaning/smoothing, and polishing? I'm not knowledgeable of metal stripping/polishing, so don't think you'll insult my intelligence with simplicity. I am really interesting in trying to replicate what you've done, so am considering it for my 1995 XJR magnesium cam cover that all the sudden looks as sad and bubbly as all the other X300 cam covers I see out there.

 

Is the supercharger ducting is also made of magnesium alloy like the cam cover? I noticed my supercharger ducting is not smooth like the cam cover.

 

I think it's made out of aluminum...
that's just a guess though.