Factory sealant turns white engine bay yellow-ish?

[RMac42]

Hey guys,

I'm looking at buying a low-milage one-owner sedan that was apparently parked for several years. Interior is mint and the Alpine white paint still shines. The engine bay, however, has gone yellow-ish. The owner says it's a common issue with white E30s that is the result of aging factory sealant. Just wondering if someone could confirm that statement.

I'll attach a photo. Thoughts? I'd appreciate your input, specifically regarding the yellowing but also about the bay in general. The owner is out of state so I have not seen this in person yet.

Thanks!

[Vivek]

Yes, he's correct. It's cosmoline, the rust-proofing stuff that BMW used on e30's. It's all over the underside of your car too, you just can't really see it.

[oliver.r]

That's factory cosmoline, I would be concerned with his claims if it didn't have it

[RMac42]

Awesome, thanks so much guys. Any way to clean it up, or best to leave it as is?

[Court M3]

You can clean it if you are OCD and want to get rid of the grime.

[Mr. Tasty]

I am local so if you ever need help. Also join azbmw.org

[RMac42]

You can clean it if you are OCD and want to get rid of the grime.

Cool. Definitely a little OCD, but I might just leave it.

I am local so if you ever need help. Also join azbmw.org

Thanks man, I appreciate that! I'll register right now.

[ForcedFirebird]

Lot's of elbow grease, pressure washing, and some OCD, and it comes clean.

We clean every customers' engine bay that comes in the shop, this one was just as bad as yours, you can see slight evidence near the hood hinge.

[StereoInstaller1]

Here are a couple of shots of a Cosmoline removal job I did a couple years ago.

We tried all kind of different stuff, including google searches. Found out that Mineral Spirits will clean it off when it hasn't been heated, but just about nothing will when it is yellowed.

This car was bad, even after cleaning. Note the yelllow goo on the hood pivot tube, behind everything, all over...totally nasty:



Then after goofing around with several methods, we found that a combination of steam and a chunk of MDF will scrape it off easily.

Then we found using a heat gun and a spray bottle before scraping makes it even easier, you can see here just how bad it was:



But, after much cussing, scraping, and backbreaking work, we ended up with this:



Get to work!

Luke

[RMac42]

Wow, so clean! Nice work... Looks like a big job, but good to know it can be done.

Thanks for the tips!

[fresh_TD]

Here's what mine looked like before and after..



Sent from my GS4 Active

[fresh_TD]

The Cosmo lime is ugly, but if the car has no rust in the engine bay, then it served its purpose ;-) a lot of factories back then used Cosmo lime to prevent rust..

Sent from my GS4 Active

[StereoInstaller1]

The crappy part is knowing that when these cars came off the boat and got to the dealer, this crap was supposed to be washed off with mineral spirits before the customer even got the car. Some cars even came with a bottle under the hood...but they didn't, because it was so shiny and looked awesome, they just fired them up and drove off...in Cali, they were yellow in a few weeks.

[StereoInstaller1]

The Cosmo lime is ugly, but if the car has no rust in the engine bay, then it served its purpose ;-) a lot of factories back then used Cosmo lime to prevent rust..

Sent from my GS4 Active

It is called Cosmoline

[ZM Blue Devil]

Here is what it could look like after some "cleaning" ;D