Ok detailing gods, I joined just to seek your wisdom on this - ENGINE BAY FILM

[Old Tiger]

CarPro PERL masks better than all else IME.

[Lints]

I just got finished working and restoring under the hood of my 1995 e36 M3. My airbox had that same film on it!

I originally though someone spilled coke or a beer while working under the hood, and never cleaned up the residue. Same thing as you, I could scrape it off with my fingernail. Well anyway, I scraped it all off, and lightly sanded what was left.

After seeing your post, I'd have to agree it is some kind of BMW coating or clear coat.


I'd advise using some of Mike's advise, do a test spot! Before scraping away and sanding the entire thing, just do a small area so you can be sure it finishes out like you want. My airbox didn't come out perfectly, in hindsight I'd repaint it, but some fine grit sandpaper got rid of the worst of it and the scratches left behind aren't really noticeable.

[TurboToys]

Wow thanks for the quick responses guys! Quite an active group here. Thanks for your thoughts Mike, I've watched your videos an they are very helpful. And thats a great M3! I may be heading to full respray town on mine though. Clearcoat failure on red cars sucks

I think you guys are right. Just found this on Pelican Parts' DIY on painting the intake manifold...

"Now we have to clean and prep the intake manifold. Chances are, there is a yellowish film all over the manifold. This is called Cosmoline. BMW used to ship the cars from Munich with a protective coating all over the cars. This is what the Cosmoline is for. Most dealers used a special solvent to remove all the Cosmoline. Usually they neglected to clean the engine off, leaving the yellowish film. In order to paint the manifold, we will need to clean it off. I’ve found that acetone works best to get all the Cosmoline off. Try to find an acetone that contains xylene, as this is an industrial cleaning agent and will work well to clean off the Cosmoline. Clean every inch of the manifold. We need to create a clean surface so the paint will adhere. Once clean, use some painter’s tape to cover the mating surfaces for the intake runners and also for the throttle body."

Anything you would recommend for cosmoline? Acetone will probably melt the plastic parts.

any solvent should take care of cosmoline, that is the same substance used to ship bearings , etc. i have installed new bearings in pipe casting machines, these bearings were over 36" ID, and were wrapped in paper soaked in cosmoline. we used mineral spirits to get rid of it and clean it up, but i would guess any good solvent would take care of it.

[Eric@CherryOnTop]

I would try some clean brake fluid (not brake parts cleaner) in an inconspicuous spot. This stuff eats through paint, so be very careful not to get it anywhere you dont want to see substrate.


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[GettingStarted]

If it is cosmoline would a dedicated product like primas cosmo remove it?

[Setec Astronomy]

I just skimmed over this...but Cosmoline is oily stuff and wouldn't leave a flaky film like that. How many owners has this car had? At one time (and maybe still) it was common practice for used car dealers and used car departments at new car dealers to steam clean engines and spray a clear coating on the hoses and plastic to make them look shiny and new. This is sort of like the Sonus Trim and Motor Kote and the old Meguiar's Engine Kote that Mike Phillips was referring to.

That would be my bet, that at one time it was prepped for used car sale and had that stuff sprayed all over. How to get it off I don't know, I would try mineral spirits (just to throw some more fuel on the fire, so to speak).

[BlueBavarian]

Thanks for all the input guys. I got some GoofOff and man that stuff is serious. Should have worn gloves, feels crazy on your hands.

I used brillo pads and GoofOff on the spark plug cover, it came out a little rough with some spots (probably from all the chemicals and abrasives I've assaulted it with)



I put some aerospace protectant on it and it looks ok now but not good enough



Also tried it on a small plug cover



Had the best results on the fan shroud



Some success on the intake box test area, this is going to have to be painted or powder coated. As I mentioned earlier, a prev owner (I'm the third) like zip ties.



And a little improvement on the right half of the injector cover



Check out that valve cover. No sealant in the world is going to blend that. To the powder coat or paint? That is the question


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[swanicyouth]

I just skimmed over this...but Cosmoline is oily stuff and wouldn't leave a flaky film like that. How many owners has this car had? At one time (and maybe still) it was common practice for used car dealers and used car departments at new car dealers to steam clean engines and spray a clear coating on the hoses and plastic to make them look shiny and new. This is sort of like the Sonus Trim and Motor Kote and the old Meguiar's Engine Kote that Mike Phillips was referring to.

That would be my bet, that at one time it was prepped for used car sale and had that stuff sprayed all over. How to get it off I don't know, I would try mineral spirits (just to throw some more fuel on the fire, so to speak).

I agree. Cosmoline used to (may still) come on new cars on various engine/exhaust parts and still comes on replacement parts like rotors. It's to prevent rust or corrosion. It's not cosmoline in those pictures.

It didn't come on any plastics - because they don't corrode or rust. Plus, cosmoline doesn't leave a film like that.

It could be some shiny engine dressing gone horribly wrong...but to me it looks like the "rust proofing" spray we used to sell years ago as part of a rust proofing service. This stuff was the color of snot but like undercoating. It came in a pressure tank and people would spray it in the doors channels where the rain is designed to come out and in various other locations. People sprayed it on engines as well out of stupidity.

I believe places like Ziebart still sell this "rust protection" in the aftermarket. It's also popular in the UK because of the climate. Here is a pic I found of what it looks like. You can see it on the right side of the left square:



Something probably rusted on the car at one point and someone decided to slather the whole under hood with rust protection and over time it baked on.

[Setec Astronomy]

Well, I dunno what that stuff is, but I'd stop rubbing those plastic parts with abrasive stuff like that Scotchbrite (or previously mentioned wire brush and sandpaper) or your going to scuff everything up (as you're doing). Likely you just need to find the right solvent that's going to dissolve that stuff without dissolving the plastic. That's why I recommended mineral spirits as it's pretty benign. Might try the 3M adhesive remover, also. Since you've written off the dist. cover already, that might make a pretty good solvent check piece, although there is no guarantee that's the same plastic as all the other stuff. Good luck.

PS The brake cleaner you used, was that acetone or perchlor-based?

[BlueBavarian]

I'd stop rubbing those plastic parts with abrasive stuff like that Scotchbrite (or previously mentioned wire brush and sandpaper) or your going to scuff everything up (as you're doing).

I only used the abrasives on the test piece (the distributor cap cover). The fan shroud, small cover, and intake box were only GoofOff on a shop towel.

That's why I recommended mineral spirits as it's pretty benign.

I would like to try this, maybe on the test piece as you suggested. If you look in front of the fan shroud at the plastic on top of the radiator the film is much thicker there. The GoofOff made some headway on it but not much. The section that looks clean on top of the radiator was that way before i started (maybe it chipped off).

PS The brake cleaner you used, was that acetone or perchlor-based?

It's this stuff. Think it is acetone based.