This is the reply I received on the Liquid Electrical Tape:

"Subject: RE: LET on Rubber Bushings & Motor Mounts

If its intermittent/occasional contact with fuels it may work, but the LET was not meant to be in constant contact with fuels.

Our LET in vinyl dispersion, while the 3M product is a nitrile-butadiene, which is more chemically resistant than vinyl in LET. "

My wording again, another pricier, but probably better coating is:

Goodrich 74-451-127 Age-Master No.1 Rubber Protective Agent about $177 low price per quart, but that would probably be a lifetime supply for a car. It is also a hazardous material.

The 3M stuff looks like serious stuff. That's when you need to run a fan to blow the fumes away from you. Their notation of using it on "synthetic rubber" could indicate a no for the standard rubber mounts and bushings on these cars. The liquid tape is a possibility. Says flammable so will need to see if it entails petroleum distillates.

Everything seems to point to silicone. There are also silicone sprays but they would likely just treat or soak the rubber but not necessarily provide a substantial/long term coating

LanoCote is listed as being safe on rubber.

http://www.seascrew.com/PDF-Files/lanocote.pdf

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

The specs on CRC's version of LanoCote are on point. Have not looked at other markets. Availability could be an issue.

I spent some time this morning searching different things, I found the following product that might be a good one to consider for protecting rubber bushings & a few other things:

https://www.lord.com/products-and-solutions/coatings/lord-hpc-5c-coating

5C is just one of the products they offer. It is available in black and other colors.

Wow, I knew I had seen that exact product somewhere before. It was in my favorites regarding protection of the whitewall part of a tire. Good find. Will have to weigh price and availability on all of these.

I checked with the regional sales rep for Lintech, ( located in Dallas ).

Regretfully this product is most likely used by the guys with deep pockets, probably government departments. He said a sample size of the 5C is one gallon and he believes the cost is about $250. The 3C ( 2 part product ) gallon sample size is above $400. Shelf life is about one year. No samples in stock locally due to shelf life.

Seems to be a really helpful and decent person, he volunteered to check to see if there is another product that might not cost so much. I'll check back with him mid-week.

Lanacote is readily available at any marine supply store or from online vendors.
I bought a four ounce tub at West Marine.
Now it is also available in a spray bottle.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

My concern about lanocote is it might wash off with exposure to diesel. I've searched but haven't found that specifically addressed. One thread that talks about lanocote & solvents is:

Lanocote-What to use for a diluter? - Page 2 - Cruisers & Sailing Forums

This thread also talks about the ingredients and msds.

I am going to try this.


https://www.amazon.com/Valco-Cincinnati-71522-Pack-Hylomar/dp/B071GC28QT/ref=sr_1_1?keywords=hylomar+M&qid=1581892144&sr=8-1

There are serveral things I have been trying to rejuvenate or repair old rubber:

1. Soak the motor mounts in Aerospace 303 overnight before installation. The guy who runs the youtube channel "sweetprojectcars" swears by this and I have been impressed with the results I have tried. I now soak everything in bucket filled with 303 for days before installation. Once the mounts are in the car, regular dousing with 303 will help preserve the mount.
2. Coat the motor mounts in silicone grease before installation. This is a Bergsma recommended tip.
3. Coat the motor mounts in Krytox 105,preferably before installation, but also after installation. Krytox is a fluoride based oil which is used for preserving sun roof and convertible top rubber seals. This is a real high-tech and effective solution for preserving rubber and essentially makes it impervious to chemical attack. Krytox costs a lot, but you don't need much.

I think Silicon lubricant conditions rubber without degrading it. At least the condom manufactures say it's safe with latex. LOL

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1983 W123 300TD US spec Turbo engine, with Euro bumpers and manual climate control, and manual transmission.

Motor mounts cost like $75 ur talking $15 for a product that 'might' protect them and an a few hours of extra labor a year to meticulously wash and reapply the coating. Not to mention you will probably need a need.bottle of whatever product you decide to use because it may get lost in the garage or used up elsewhere.

This doesn't seem like it's worth it. Your saving maybe a few years of life on a part that's gonna last 10-15 years. Who knows if your even gonna have the same fire and excitement for the car then, let alone even still own it

It will be the same cost and labor time in the long run to just spray them with water every engine bay cleaning and getting new ones when they go bad

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Slicone will remain flexiable and is impervious to oil. It is what is used in sealing oil pans on etc at times remember.

I would buy clear silicone as you can see how much you are applying. Although black is available I believe. It also bonds well to rubber and many other materials. Or at least well enough to avoid separation. If they are clean.

No sense looking for a specialty item. Chances are it would be expensive and no better in reality. A 5.00 tube or less from the hardware store should do it. Technically one might even clean the oil off an existing one and coat it up. Laquer thinner although flamable is the beat clean up solvent. It does not leave any residue behind and evaporates fast.

When I did my 1999 E300 motor mounts the Left Hand / Driver's side came with a protective cover for the mount. I wonder if it is available separately?





Motor mount and cover

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1999 Mercedes E300TD daily driver sold at 238K miles 106K miles were mine, rust worm got it :-(
2006 Mercedes CDI new daily driver! 56,000 miles May 2016 now 85,625 Apr 2018 and Apr 2019 101,000 miles Apr 2020 109,875. March 2024 135,250