Polishing the valve cover

"are you then to put a thin film of it on the face of the gasket and the face of the bare metal or are those surfaces suposed to touch completely clean"

Well Chris, when I did mine a while back (3 years?) I put a bit on each side. Not so much that it oozes out when pressure is applied. It's never a good idea to reuse the VC gasket though. It's cheap enough insurance to put a new one on. I mean you're willing to put 20 hours of labor into polishing the thing, give it a new bed to lie on!

Do you have experience with polishing metal or will this be your first go at it? I've threatened to try it on various autos through the years, but alway chicken out!

Good Luck! John B. '91 Classic Red

Chris, I have polished a bunch of them. Yes, you will need to remove it from the engine. You will also need to remove the sheet metal parts inside (to ckean the cover before & after polishing) It depends how old the rubber gasket is, but you should replace it just to be sure that you won't get oil leaks. I think if you go to the Miata.net, there is a section in the garage section that shows where to put to the silicone seal.

To do a good job of polishing, you shuold :

Clean inside and out (paint thinner works good )

Remove the "extra casting flanges" along the sides with a good file.

Use a power "flat" hand sander to sand ALL of the large area (the casting looks like the back of a camel and is anything buy flat ! )

Use finer sand paper untill it shines and all the scratches are gone.

Use rubbing compound to get the shine you want. (clean the BLACK off with soap and water as needed)

Use "Met-all" or "Mothers" Alum polish to finish.

When you are finished with the polish, use "baking power" on a soft cotton cloth to remove all of the polish and moisture (removes all of the black crap)

Replace the sheet metal inside and put it back on the engine ? per the info in the garage site.

Good luck,

I have done all of the Alum. parts on my engine, intake manifold, water inlet / outlet. ...... everything that is Alum.. You will love it when you are finished, but it will take time to do it properly.

Maybe I can get Leon to get some pictures of it when he comes up to Seattle and put them on the site for others to see. :-)

Bruce RED '91

The latter. If you don't install a new one, Murphy's Law guarantees the old one will start leaking within a week of reassembly. For the same reason, always replace the cam angle sensor O-ring while the cover is off and it's easy to do.

No RTV on the mating surfaces! Apply small dabs only in the six corners indicated, where the gasket has trouble sealing on its own. The hardest part of the whole operation is cleaning the old RTV off the cover and head--don't make it even worse for next time. And don't even think about replacing the cover without cleaning off the old sealant.

Good point, anyone know the approximate cost of that gasket?

I've polished a little bit od everything, I'm thinking a trip to get a couple dremel tool bits might be in order.

Chris

Thanks, couple good points. That intake looks like quite a job, eh?

I have a very good looking STB that this will really compliment.

Chris

Gottcha!

Thanks, Chris

Hi Chris,

Yes the intake is a job. I took all of the "webs" out from between the flow tubes and then flowed all of the tubes as round as I could make them. ( I also did a "little" enlargement of the insides to match the head ports :-) ) Lots of work, but it sure is nice looking ! I had an extra Intake manifold and Cam Cover to work with so the car was not held up while I worked in them.

Bruce RED '91

About $8.50 at my local Car Quest parts store. $30 at your dealer, $23.68 at Trussville Mazda.

YOWZA! Truly nice looking, those polished covers. But after reading all that....uh....I think paint might be an option.....

Of course, I'm still trying to figure out how to effectively clean the engine compartment on my old '91.

D>Gottcha!

Simple Green. Though I do not know it will satisfy anyone who wants to polish their engine parts.

Personally, I am aware that the hood does not allow enough photons to tunnel through for the human eye to discern parts, however well polished. Or notice dirt.

Isn't knowledge of physics wonderful. :)

Leon

Sure, Simple Green and rinse with water is a very good way to clean under the (US) hood . I use it all of the time on all of my cars (polished or not. :-) If you just keep at it, soon it will be nice and clean. After you get it as clean as you want, just put some wax on all of the body painted parts and it won't get dirty easy. I pull the plug wires and use 4 corks to keep the water out of the spark plug holes when I turn the water on it.

Have fun with it ! It is easy to keep your hands clean when working on a clean engine.

Bruce RED '91