Anyone done this? I have a pair of Phoenix/Lemforders here for my W123 that I haven't installed yet. I know that any dino fluid that gets on them can accelerate their aging. Aside from regularly degreasing them has anyone ever tried coating them with something as a passive protection? While filling the hollow cavity with urethane helps I want to address the deterioration of the black rubber. Of course the ideal is a bone dry engine bay and the ability to stop a leak before it happens and maintenance procedures that don't lose a drop of diesel, oil, atf but I'm just not there.

How about an upside down sheet metal cup over the top of the mount? Many MB have a similar setup as a heat shield.

Shrink wrap plastic

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Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"

There is a metal plate on top of these but it doesn't address the 90% of the exposed rubber all around. A metal wrap could help though. Shrink wrap plastic could work as long as it doesn't age-out from the environment. I even thought of just bagging them but it would have to be serious stuff to hold up for years.

Something liquid/flowable/sprayable would get into the base where the metal and rubber meet. It would have to be flexible though and not petroleum based.

Wax? Might see what sorts of wax might work on rubber. Edit: Nope, forgot about the high heat factor. I'll try anything if it's easy enough and won't obviously make things worse. A coating of silicone adhesive might stick well, flex, and isn't degraded by said fluids.

I don't know if you'd dare try this https://www.amazon.com/SP-400-Corrosion-Inhibitor-Aerosol-Amber/dp/B07FZ53KFF

crc sp-400 is interesting stuff, as a corrosion inhibitor it's perhaps the best for durability;
dries to a thin wax coating that isn't flammable (I've tried)

It's made for machinery storage outdoors. I use it to protect metal that will rust, but isn't feasible to paint. Comes in super handy for undercarriage, brake lines, rusty parts, etc. I like it so much I got the "forever" 5 gallon bucket (I hated how the spray put so much into the air)
It's nasty stuff, basically cosmoline in a solvent to make it spray-able. Do NOT breath any of the mist.

In the spray version, I imagine the solvent will evaporate pretty quickly and not have too much effect against the rubber

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1985 300TD 1981 Scirocco 1.6D conv 1986 Golf 1.6D 2003 Golf TDI

Good angle on the wax but a search shows it to be a "heavy petroleum-based film." I know the Brits especially use tons of this type of stuff to preserve old cars. A synthetic version of this might work though.

Are they polyurethane like bushings for front end parts? If they are there is nothing you can do, they are inherently turning back into a liquid.

Just clean the oil off once or twice a year and you'll be good to go .

Ignoring the accumulated oil from leaks, weeps, seeps and spills is ruinous to every plastic part there too, why some have endless problems and always needs ever more parts and others don't .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

or totally encapsulate the mount in 3m windoweld (also used for filling mounts)

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1985 300TD 1981 Scirocco 1.6D conv 1986 Golf 1.6D 2003 Golf TDI

I've smeered Permatex Ultra Black RTV on mounts before with good results.
https://www.permatex.com/products/gasketing/ultra-series-gasket-makers/permatex-ultra-black-maximum-oil-resistance-rtv-silicone-gasket-maker-4/

But it's tough to get down in the base crack.

I also used the as seen on TV Flex Seal spray on CV axle joint boots to protect them.
https://www.flexsealproducts.com/product/flex-seal/
Seems to be holding up well on the boots. Perhaps it might work on the motor mounts too.


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Cleaning the mounts was mentioned. Looking for passive protection for in between the once or twice a year cleaning. The difference could be a matter of one extra year of life vs years more life if the mounts can be totally sealed from the elements.

Someone asked about rubber on a FlexSeal product page and the answer was something along the lines of 'it's not specified but you could try it'. It's petroleum based but maybe certain compositions of rubber aren't as vulnerable.

The 3M and the Permatex look like the strongest candidates. It might come down to the best adhesion to rubber.

I stuff a rag on top of the mount before oil and fuel filter changes. I also hold a bowl beneath the fuel filters when I break the loose and ease the filter down in the bowl when it's free.

I also filled the cavities in the mount with shore 30 urethane to slow their collapse.

I had a pair of shields but they were a paint in the rump to line up so I didn't install them.

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84 300SD
85 380SE
83 528e
95 318ic

Yes, basic active prevention and urethane was already mentioned. Just looking for passive protection of the black rubber.

I've been looking for a coating that might extend the life of the rubber bushings, I guess motor mounts are just big bushings.

Pricey, but probably enough for several years:

https://www.gracosupply.com/3m-scotch-weld-ec-776-fuel-resistant-coating-quart-with-specs

data sheets:

https://multimedia.3m.com/mws/media/241258O/3mtm-fuel-resistant-coatings-ec776-and-ec776-sr.pdf

After reading the safety data sheet, I might not use it. But it is most likely an excellent product.

https://multimedia.3m.com/mws/mediawebserver?mwsId=SSSSSuUn_zu8l00x4xtvN82Smv70k17zHvu9lxtD7SSSSSS--


also this product might work quite well:

Liquid Electrical Tape

Liquid Electrical Tape - LET

I've contacted them to see if it would work to help protect the rubber against ozone & fuels. They think it will but they said they would check & send an email. If it does provide good protection to rubber bushings then they could probably sell a lot more if it was advertised that way.