1984 W123 300D Vacuum Brake Booster Line - PeachParts Mercedes-Benz Forum

runnersigh · #1 04-07-2021, 10:47 AM

Anybody know where to find them or have they become unobtainium?

dogguy · #2 04-07-2021, 08:30 PM

Quote:

Originally Posted by runnersigh

Anybody know where to find them or have they become unobtainium?

One could choose those currently offered at peachparts.com and elsewhere. Availability does not appear to be a problem for that part which travels between the "Brake booster to vacuum pump" for a US 1984 300D.

Diesel911 · #3 04-07-2021, 09:30 PM

Is it the hard plastic parts that broke?

runnersigh · #4 04-08-2021, 08:13 AM

Quote:

Originally Posted by dogguy

One could choose those currently offered at peachparts.com and elsewhere. Availability does not appear to be a problem for that part which travels between the "Brake booster to vacuum pump" for a US 1984 300D.

They list as in-stock but ordering them gets you an email that says 'unfortunately we are out of stock'

runnersigh · #5 04-08-2021, 08:15 AM

Quote:

Originally Posted by Diesel911

Is it the hard plastic parts that broke?

Yes, the line is fine bit I broke the nipples that come out and supply the vac to other parts

Diesel911 · #6 04-08-2021, 11:26 AM

Quote:

Originally Posted by runnersigh

Yes, the line is fine bit I broke the nipples that come out and supply the vac to other parts

If you need a temp repair till you find a new line and you still have the broke off nipples what I did was I got a drill bit (the drilling end inside) that approximated the size of the hole in the nipple and I epoxied it back on. After it cured I carefully turned the drill with a pliers and that left the nipple attached. I did that to 2 of them.

Then I got some new longer vacuum Hose and carefully shoved that over the nipples. If you left it like that the nipples can still break off. So what you do is you Coat the section of the hole the nipple is in all the way back and round the plastic with epoxy and do that enough times to form kind of a Cast over the hose and the nipples and the plastic.

They you connect the hoses as you normally would. Later I replaced the plastic vacuum line with longer rubber hose and that allowed me to route the main vacuum line over the fender well better.

The other way is more complicated but more permanent. The hard plastic part contains a Check Valve for the Brake Booster.

You can buy generic check valves. Some I have have aluminum bodies and you can get brass fittings or other plastic/nylon fittings to replace the whole nipple section and cut off the old vacuum line and connect them with rubber vacuum hose. You could even use silicon vacuum line instead of the rubber one.

You can see the check valves on eBay. They are more frequently used on the suction side of fuel systems.

There is a picture in post #14. Back in 2007 when I did my first Oil Change I leaned on the line and broke off the little plastic nipples. The repair looks ugly but is still in use.
http://www.peachparts.com/shopforum/diesel-discussion/408912-slow-start-no-start-82-300td.html

A pic in post number 5 off a generic check valve with an aluminum body.
http://www.peachparts.com/shopforum/diesel-discussion/398740-injection-pump-check-valve.html

runnersigh · #7 04-09-2021, 09:04 AM

Quote:

Originally Posted by Diesel911

If you need a temp repair till you find a new line and you still have the broke off nipples what I did was I got a drill bit (the drilling end inside) that approximated the size of the hole in the nipple and I epoxied it back on. After it cured I carefully turned the drill with a pliers and that left the nipple attached. I did that to 2 of them.

Then I got some new longer vacuum Hose and carefully shoved that over the nipples. If you left it like that the nipples can still break off. So what you do is you Coat the section of the hole the nipple is in all the way back and round the plastic with epoxy and do that enough times to form kind of a Cast over the hose and the nipples and the plastic.

They you connect the hoses as you normally would. Later I replaced the plastic vacuum line with longer rubber hose and that allowed me to route the main vacuum line over the fender well better.

The other way is more complicated but more permanent. The hard plastic part contains a Check Valve for the Brake Booster.

You can buy generic check valves. Some I have have aluminum bodies and you can get brass fittings or other plastic/nylon fittings to replace the whole nipple section and cut off the old vacuum line and connect them with rubber vacuum hose. You could even use silicon vacuum line instead of the rubber one.

You can see the check valves on eBay. They are more frequently used on the suction side of fuel systems.

There is a picture in post #14. Back in 2007 when I did my first Oil Change I leaned on the line and broke off the little plastic nipples. The repair looks ugly but is still in use.
http://www.peachparts.com/shopforum/diesel-discussion/408912-slow-start-no-start-82-300td.html

A pic in post number 5 off a generic check valve with an aluminum body.
http://www.peachparts.com/shopforum/diesel-discussion/398740-injection-pump-check-valve.html

Awesome, thanks for the help! What size rubber/silicone hose did you use?

Diesel911 · #8 04-09-2021, 12:11 PM

Quote:

Originally Posted by runnersigh

Awesome, thanks for the help! What size rubber/silicone hose did you use?

It was a long time ago. 1/8 inch ID would be the smallest to go. Silicon Vacuum hose when new can stretch from the original 1/8 inc ID on up to 3/16 ths very easily.
Again it was along time ago the large main line I believe I used 1/2 inch or smaller rubber vacuum hose on. I bought that at the local autozone. If you do that take one of the steel main line fittings with you so you can compare the Hose ID to what you need.

unkl300d · #9 09-22-2021, 07:06 PM

peachparts not in stock. besides it may say in stock and allow the order to go thru then later you get the email saying it is not available anymore.
Stinks!

mercedeswerks has them in stock right now good price for the up to 1985 ones

BillGrissom · #10 09-24-2021, 06:16 PM

There was another thread on exactly this a month ago. Common problem when people lean on an elbow under-hood, and not a tough repair. First time, I drilled out the broken nipple to fit a small copper tube which I epoxied in the hole. Probably 1/8", but could have been 1/16", something I had in my "bag of tubing". Many of the rubber under-hood vacuum lines I replaced with silicone hose (1/8", forget). It is stretchy so can fit over many nipples. I use blue to look purty. Since that fix, I procured several junkyard "Main vac tubes" so I'm set for life and not selling them.