Are there any experts or hobbist out there who knows anything about liquid rubber or anything along those lines ???

I want to "mount" 2 of the standard yellow vacuum lines inside a rubber hose to make a fitting. I am thinking 2" should be enough coverage. The ID is around 9mm. I need to fill the inside with something which will last a life time. Think of what I am making as a rubber stopper (sort of) with 2 holes in it. Instead of holes, there are 2 plastic yellow vacuum lines emerging. These are the common yellow lines from a W123 which run all over the place.

RTV Silicone. Check it out.

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62 220sb
67 250S
72 280SE 4.5
74 280C
77 300D
82 240D
85 190E 2.3
86 300E RIP 12/28/09
85 300SD
92 300D 2.5
00 E320 Current
Over 1,000,000 miles in Benzes, Since66

....and a whole passel of BMW 2002 and Tii

rtv red or clear is good for about 1/4 inch cure depth sometimes more but not much
for larger or thicker cross sections you will need a two component mix
i will give a specific compound in the morning but look up the urethane mixes of differing hardness

http://www.1sourcedist.com/Product/Details/4175038

too much money for casual use but it works well

Polyurethane should do the trick. I've used it in filled motor mounts, sealing my modified glow relay, rebuilding steering coupler, sealing NSS pigtail and so forth. I bought a two quart kit - don't know if it comes in more convenient quantities.

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Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

I am thinking I will need a few oz's ... the ultimate key is that I do not want any vacuum leaks (or any leaks).

Thanks for the responses. Please let me know what's out there and where to buy this stuff.

Check out the "smooth-on" products. The trick is finding some place locally to you that sells smooth-on stuff where you can take a look at examples of the various hardnesses of plastic or rubber kits, but you can basically make anything you want with things they sell. A bit pricey, or more than a bit, but ve had good results with a lot of their rubber mold making products. You could go to even a very hard plastic if you wanted, like a sealed electronic component.

Its all available on the web, i think they have a pretty good catalog

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Why not use an actual rubber stopper?

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

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"

Tinkered with it and it won't work. The stopper is tappered and no way to get it jammed into the hose without leaks. I can drill out the holes for the 2 vacuum lines a little, but its too problematic. I am looking for something which takes one shot and will last forever without issues.

I am only looking at approximately 2-3" max off the steel nipple. That should provide plenty of coverage along the vacuum lines to guarantee no leaks.

What about urethane windshield sealant? Adheres to rubber quite well, very durable and available at any auto parts store. Maybe your local windshield guy would give you an almost empty tube of it....

I'm not finding it on PP, hence the following link.


Advance Auto Parts: Search Results for windshield urethane

But not any silicone, use Permatex Right Stuff; it has Carbon, lots of it in the RTV. VERY strong, I've made all sorts of rubber/vinyl/body trim repairs with it and none of it has let go yet (8 years).

Try this - Reynolds Advanced Materials

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Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

Here is a picture of the mock up. Obviously, the tubing will be standard, regular rubber tubing and the yellow lines are standard, regular MB vacuum tubing. The steel nipple from the vacuum pump is around 3/4" long and I am thinking around 2" or 3" of rubber hose. Inside will be the 2 MB vacuum lines (3.5mm). They will be "centered" as much as possible with the rubber goo inside and around and compacted as much as possible to eliminate air pockets, et cet. I think 2" or even 3" of surface contact should be enough to eliminate all possibility of a vacuum leak. This will be mounted in the trunk so it will not have a ton of vibration or jaring. This stupid little part or project appears to be the show stopper for manual brakes and the EVP. One line will be a straight shot to the under the dash connected to the vacuum supplied items and another line to the resevoir with a "T".

That black goo for windshields seems pretty tuf ?

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Lot of good answers already...
but there is a product I think everyone needs to know about anyway.... and might do here... although I suspect for this application it may not have enough viscosity...
It is ' Liquid electrical tape '.... Permatex and several others make similar products... I have used it for decades... it is pliable and tough..... really nice where you may not can reach to put a shrink tube... or can not put heat to the area to shrink the heat tubing... etc... as this has a brush to apply in some of the products... You can apply multiple layers... if needed... or cover with shrink tubing ... after you let this set up completely... can make an electrical junction water tight....
I think everyone ought to have a bottle or can of this stuff in their emergency fix kit....along with a 12 volt soldering iron.... and really thin solder...in addition to a AAA membership card.... LOL... on cars this old....

For good reference material.... check with 3M products catalogs....

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

Plenty tough, especially in this application. The consistency of the uncured urethane is stiff enough that it won't flow away from your vac lines before it cures, yet will enable you to work it thoroughly around and between both lines to eliminate leaks. Once cured, you're not going to worry about a leak even if it is subjected to vibration, etc.

Performix Liquid Tape:

Liquid Tape: Unity in Quality | Plasti Dip International

Performix Plasti Dip

http://www.plastidip.com/home_solutions/Plasti_Dip

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Sam

84 300SD 350K+ miles ( Blue Belle )