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A stupid question I am sure, I noticed a long time ago that the heads on my 540 are gray..never thought anything of it until a friend asked me the other day if they had been rebuilt or not because of the color. I know in the 2 years I have had it that they havent been rebuilt or removed, but thought I would ask others what color theirs is. Mine is gray, and it looks like the covers are gray as well but they were painted black and that paint is coming off.
 

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My '95 are a crinkle gold, the '99's were crinkle gold, my buddies '98 are crinkle gold and the M5's are ....................................... guess what I'm trying to say is that a crinkle gold is probably the correct color choice
 

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A stupid question I am sure, I noticed a long time ago that the heads on my 540 are gray..never thought anything of it until a friend asked me the other day if they had been rebuilt or not because of the color. I know in the 2 years I have had it that they havent been rebuilt or removed, but thought I would ask others what color theirs is. Mine is gray, and it looks like the covers are gray as well but they were painted black and that paint is coming off.
The pic shows pealing paint on the valve covers, which were originally a pale gold color. The heads below look original.

Most 540's develop valve cover leaks and it is quite common to paint the valve covers while their off to replace the gaskets, the original paint usually peals quite badly.

I believe the valve covers are made of magnesium, which requires a special primer to do "correctly," and seem quite prone to rejecting any paint put on them. Many people have the valve covers powder coated, which seems to hold up better than paint.

Jim
 

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BTW, the engine itself is bare aluminum; not painted.
 

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The pic shows pealing paint on the valve covers, which were originally a pale gold color. The heads below look original.

Most 540's develop valve cover leaks and it is quite common to paint the valve covers while their off to replace the gaskets, the original paint usually peals quite badly.

I believe the valve covers are made of magnesium, which requires a special primer to do "correctly," and seem quite prone to rejecting any paint put on them. Many people have the valve covers powder coated, which seems to hold up better than paint.

Jim
Yes... Powder coating is the best route to go.

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Im confused...

your asking about the valve cover which was black, and the head that was aluminum?

and whats this guy talking about gold? bmw never painted anything gold... except for i think the e30 m3 which had black on gold
 

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Im confused...

your asking about the valve cover which was black, and the head that was aluminum?

and whats this guy talking about gold? bmw never painted anything gold... except for i think the e30 m3 which had black on gold
B2, not sure what the confusion is, I have never seen a 540i that didn't come from the factory with gold valve covers. As ed has said, the head itself is bare aluminum.

Have never found a spray or powder coat gold that matched the original factory color.

Jim
 

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They aren't painted gold. There is a protective coating on them that has yellowed over the years.

It's called Cosmoline and BMW has been using it since before the E30.
Right. Aren't they actually silver? With "gold" cosmoline flake. Ha.

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Brandon, I don't see how it is possible that there was a Cosmoline film on them.

"Cosmoline that is fairly fresh, or that has been hermetically sealed in a plastic bag or shrink wrap, remains a grease-like viscous fluid, and mostly wipes off with a rag, leaving only a thin film behind. Cosmoline that is older and has had air exposure usually solidifies after a few years, as the volatile hydrocarbon fraction evaporates and leaves behind only the waxy hydrocarbon fraction. The solid wax does not readily wipe off. It can be scraped off, although the scraping is laborious and leaves crumbs to be swept or vacuumed away. One method that may help remove cosmoline is to apply gentle heat sufficient to melt the waxy hydrocarbons, the Cosomoline may then be wiped off metal or allowed to drip off of wood."

Cosmoline would melt off the first time the motor got hot. I'm also pretty sure there is grey primer under what ever coat has been factory applied.

Jim
 

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Jim, remember the last time you debated something with me? Magic synthetic oil that thickened as it got hotter?

Its fact that BMW has used Cosmoline as an engine coating for decades. Do some more research. Its Cosmoline that has hardened, baked and turned a yellow hue. I've had customers that wanted it removed and it's a PITA.
 

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Jim, remember the last time you debated something with me?

Its fact that BMW has used Cosmoline as an engine coating for decades. Do some more research. Its Cosmoline that has hardened, baked and turned a yellow hue. I've had customers that wanted it removed and it's a PITA.
LOL. You know a lot! I don't seek to debate, but to understand. :)

I know there is primer under the coat. U say'n they put Cosmoline on primer? Or am I mistaken about the primer too? that it's not really primer but oxidized magnesium?

Jim
 

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It's Cosmoline on raw magnesium. If there is primer on yours someone painted them at some point.
Mine appear to be origional factory, and gold like most others I have seen.

This from an article on how to paint BMW valve covers.

"Next, use some acetone on a rag and wipe the outside of the valve cover. Most acetone brands contain xylene, which is a great cleaning agent. The xylene will also take off all the cosmoline on the cover. Cosmoline is that yellowish film that you most likely will see in other arrears of the engine as well. This stuff was originally a protective sealant that BMW sprayed all over the cars when they were being shipped to the US. Most dealers never took the time to remove it from the engine components. Don't worry, cosmoline won't hurt anything, but after years of being on there without removal, it has most likely baked itself onto the valve cover. An acetone with xylene will eat right through it."

:thumbup:

I'm still not totally convinced, but I do see material supporting your facts. Contrary to what he has written i don't find Cosmoline anywhere else in the engine bay. My understanding is that when mg oxidizes it grows salt crystals, being that mg is a salt.
 

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Jim, remember the last time you debated something with me? Magic synthetic oil that thickened as it got hotter?

Its fact that BMW has used Cosmoline as an engine coating for decades. Do some more research. Its Cosmoline that has hardened, baked and turned a yellow hue. I've had customers that wanted it removed and it's a PITA.
This is absolutely true. It is a well documented frustration (issue is probably a strong word). It obviously does not cause any functional issue, but aesthetically it is annoying. Typically a phosphate bath will take the cosmoline off as a proper preparation for magnesium parts for powder coating.
 

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I have found an image that to me, casts doubt on the Cosmoline assertion.

For your consideration: The photo clearly shows the same color inside the valve cover as it does outside. If this is Cosmoline then they must be coating the inside of the valve cover with it also, which is not impossible, but to me less plausible.

Also, the Cosmoline would have to have been sprayed on before coil wires and gasket were put in place. Also not impossible, but it destroys what was written about it being a coat applied for shipping because the valve cover was very probably off the car when the coat was applied as there is no coat on the head, coils/wires or gaskets.

I have seen photo's of this color gold valve covers being sanded down, only to find a Bondo type of filling hiding the imperfections under the gold coat. I do not believe Cosmoline would hide "Bondo."

Being Cosmoline, abet old Cosmoline, it should wipe right off with Acetone, should it not?

Lastly, Magnesium is know as a rapid oxidizer, growing salt crystals when left exposed to air. I don't believe bmw would let un-painted magnesium out out of the the factory as the Cosmoline would be fresh and rapidly melted off the valve covers the first time the motor got hot, then the valve covers would oxidizing all over the place, being that Cosmoline is not a permanent coat. I see little evidence of mg oxidation in any of the mag valve covers.

Brandon, you're a wealth of knowledge, no doubt. I can offer no fact, only observation and some weak logic, I'm just not see the coat as being Cosmoline given what I have seen. You are so often right, and I so often wrong and likely so in this case also.


Jim
 

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