Need 1995 E300d Vacuum diagrams - PeachParts Mercedes-Benz Forum

b52rule · #1 09-03-2010, 06:51 PM

I heard a loud whistling noise under the hood after coming off the freeway. I traced it down to a vacuum line that comes off a control underneath the air filter box. The line was open, not connected to anything and ran up beside the battery.

Does anyone have diagrams of what the vacuum line routing for the three units underneath the air cleaner box for this car? One has a kind of a dome on it and says VAC ACC on the top. I can't find the diagram on the CD's I bought.

Thanks!

glenlloyd · #2 09-03-2010, 09:33 PM

I don't have the specific E300D vac diagram but according to the Mitchel trans diag manual it's similar to the 300SD/S350D W140 cars.

http://w126.pp.ru/akp722.pdf

go to page 12

b52rule · #3 09-04-2010, 11:05 AM

Thanks for the reply!

In the diagram line #22 is the issue as I just found an open line next to the battery. I have no idea what the other consumers are. Right now I'll cap that line until I come up with a better solution.

Thanks!

glenlloyd · #4 09-04-2010, 11:14 AM

Quote:

Originally Posted by b52rule

Thanks for the reply!

In the diagram line #22 is the issue as I just found an open line next to the battery. I have no idea what the other consumers are. Right now I'll cap that line until I come up with a better solution.

Thanks!

#22 should be an open line into the car for testing I believe. #23 is supposed to supply vacuum to other things like the AC door actuators inside the car and such.

If you have a loud noise coming from one of the transducers there's a test to see if it's working properly. Perhaps that's the source of your noise?

Steve A

b52rule · #5 09-04-2010, 11:23 AM

I have not had the car out since I plugged that line. The noise, consistent with a vacuum leak was coming from under the hood after coming off the freeway under high power. I'll know more later today after I take it for a run.

Thanks!

b52rule · #6 09-05-2010, 12:24 PM

I ran the car ragged yesterday with that port plugged. Everything ran as normal so now I have no idea what that line does, or where it goes. Unless someone has a diagram I'll just wait until I see one on the street or on a parking lot and ask if I can take a peek.

Unless someone has a diagram or pics somewhere.

Thanks!

glenlloyd · #7 09-05-2010, 12:42 PM

If what you found making noise was 22 in the S350D vac diagram then you've plugged the atmosphere vent line. That would suggest that something upstream of the "plug" is not working properly.

Given that you are non-turbo car I would think that you only have one vac transducer in there and that would be for EGR control.

Somewhere I have a test procedure for the vac transducer, I'll dig around and see if I can find it.

steve a

b52rule · #8 09-05-2010, 12:58 PM

The kicker is I don't know what is upstream. The open line was found next to the battery with no other vacuum line lying around to connect with. I'll keep poking around.

Don't you just love it when a plan comes together!

B52rule

b52rule · #9 09-09-2010, 09:04 PM

Another theory bites the dust..........

The buzzing sound returned after the vacuum line was plugged. I finally found the culprit. There is a part fwd of the battery with two wire connectors attached. The taller of the two, silver in color is vibrating/buzzing to beat the band. It is also rather hot, found out about that the hard way.

I have no idea what it is or what it does.

Progress! I think.

okto · #10 09-09-2010, 10:42 PM

Congratulations, mighty warrior! You have discovered AUXILIARY WATER PUMP. AUXILIARY WATER PUMP is not necessary for operation, but gives you +5 against Weak Heater when idling.

b52rule · #11 09-09-2010, 10:54 PM

That thing was HOT! Buzzing to beat the band. I'll hit the men's mall this weekend as there are several 124's and 126's in the yard. As usual I'll check part numbers first.

Thanks!