vaccuum/dieseling problem - broken part
 

A small vacuum hose part was broken when my cousin replaced the AC compressor on my '83 300d and now the vehicle diesels when I shut it off.

(On the plus side, the AC works GREAT! :-)

The part is on the driver's side, about 1 foot from the firewall and 1 foot from the fender. It has a large vacuum hose attachment on the firewall end, and several side and end nubs for small vacuum hoses.

http://jcdill.com/misc/2008-04-12-jcd-LS1F6364.jpg

We tried to mend it with crazy glue and electrical tape - it didn't work.

Given that it's a plastic part I'm assuming it's not a good idea to replace it with a used part from a wreck - is that a valid assumption?

A) Is there a special name for this part?
B) Can someone give me a ballpark estimate of what it costs?
C) Where is the most cost effective place to buy/order it?

I'm in the SF Bay Area - Redwood City (between SF and SJ). We have a local auto-parts store that many shop mechanics buy parts at (Kohlweise).

I go to SF once a week so I could also buy the part there (without a special trip - spending more in fuel than the part costs). I have another vehicle I can drive for a few days (old ford truck) so I don't have to get this fixed immediately or deal with continually lifting the hood to shutoff the engine each time I turn it off.

Thanks!

jc

It's a vacuum fitting on the main vacuum line running to the brake booster. Click on Buy Parts at the top of this page and start looking at vacuum fittings till you find the one that broke. Be careful not to break any other fittings when you replace it. Those things get brittle. I'd probably heat up the main line with a heat gun to remove it in order to avoid breaking the fittings at the ends of the main line.

That black plastic tube is the line from the vacuum to the brake booster. the plastic fittings are part of the hose set up. I broke off the same plastic part one time and the shop ordered one. think the price was around $50.00, dealer only part as far as I know.

I have grabbed a few when I have been at Pick N Pull for back ups.

Charlie

Cool! Now that I know what part I need...

I'm having problems getting that to work. I searched for 1983 300D - the options are:

300CD Turbo
300D Turbo
300SD
300TD Turbo Wagon

I'm guessing I my vehicle is the 300D Turbo. There is no category for vacuum, so I searched for "vacuum" and then clicked on all the links - none of them show this type of fitting. There are generic 3-way and 4-way 1/4 inch fittings under Vacuum Hose Connector but no other categories that show different types of connectors. (I have also looked under the other 300 models.) Is there a secret to searching or finding it in the catalog?

Thanks again,

jc

Yours is an 83 300D turbo. All 1983 300D's were turbos.
Replace the line. DO NOT try and repair it. The size of the nipple lines is critical so it is best to replace the broken unit.
When working in the engine compartment injector side it is best to remove this line. It tends to get broken easily and it's very easy to remove while working on the engine.

http://catalog.worldpac.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=2CF0TS65V2CG0T7KWJ&baseurl=http://catalog.peachparts.com/&partner=mercedesshop&year=1983&product=N4020-44957&application=000295066

It is your "brake booster vacuum line". It's under "brakes".

Dave

Yes, these plastic valves get brittle with age/heat. Replace the entire 'booster vacuum hose' line. A real easy job to do.

I had the same problem and needed one of these in a hurry. My local MB dealer had the part in stock, even gave me a discount; $21 + tax if I recall.

Thanks everyone!

Do I need any special tools to replace this line? I have a full set of wrenches and such - I just want to make sure that this doesn't require some odd-size wrench or special lock-tight or something like that. (I've never replaced a vacuum part before.)

jc

What was it doing before you shut it off?

When I say "the vehicle diesels when I shut it off" I am referring to how the engine continues to run even when I turn the ignition off (dieseling). It will not stop running until I lift the hood and press the "stop" button on the top of the engine.

I replaced the hose today. It took 5 minutes, and the dieseling is fixed. Thanks everyone for your help!

You mean your car isn't dieseling anymore?
You going to put in some spark plugs?

What some of the posters are getting at is that your car will always "diesel".
Your problem is your car will not shut off. While running, the engine in your car is dieseling because it is a diesel. If a gas engine continues to run after being shut off, then the gas engine is "dieseling"( running without a spark system).

Some here are very finicky with technical terms. I know, I'm usually one.

Glad you got it fixed.

Dave

I'm having a similar problem in that a previous owner had my transmission modulator hooked up to 1st T coming out of the firewall on a rebuilt brake booster line. I broke the T after I put the transmission hose in the right place, now I'm not sure what to plug into the 1st T in the brake booster hose. I have a 1981 300sd. Anyone have any suggestions?