240D Vacuum Diagram with Required Vacuum Levels at each point? - PeachParts Mercedes-Benz Forum

speedyspaceman · #1 12-30-2009, 08:15 PM

I have successfully found multiple vacuum diagrams and have made sure that all my connections are correct. The only problem is that I don't know how much vacuum I am supposed to have except right off the brake booster ( I have a health 24). I am wondering if someone would label each hose or connection (it may take a little) for each hose or connection not only outside the transmission valve lever box on top of the valve cover, but the little hoses and connections between the two white valve lever boxes. This would be an amazing help for many people who are trying to diagnose their mis-shifting transmissions. Thanks so much.

speedyspaceman · #2 12-30-2009, 11:45 PM

Wow! I was for sure someone would have something.

Biodiesel300TD · #3 12-31-2009, 12:09 AM

I'm not sure anyone is going to be able to tell you exactly how much vac each part of the system is supposed to have. An easier way to figure out if you have a leak is to pull vac on a particular system and see if it holds vac. If it doesn't, then move down that system until you find the leaking culprit.

speedyspaceman · #4 12-31-2009, 01:49 AM

On my 83 240D there are two vacuum tubes off the main brake booster line that supply my car with vacuum. The tube furthest away from the brake booster has very strong vacuum and the one closest to the brake booster has none. If I knew how much each line or joint has I would be able to tell if that is normal. Thanks for the reply.

Cr from Texas · #5 12-31-2009, 02:26 AM

Quote:

Originally Posted by speedyspaceman

On my 83 240D there are two vacuum tubes off the main brake booster line that supply my car with vacuum. The tube furthest away from the brake booster has very strong vacuum and the one closest to the brake booster has none. If I knew how much each line or joint has I would be able to tell if that is normal. Thanks for the reply.

They should both have vacuum. One of mine was plugged and I used a small drill bit to clear it. Do not make the hole larger, just clear it. The hole size is part of the regulation of vacuum. You do not want to starve the brake booster.

dannym · #6 12-31-2009, 09:18 AM

A little impatient are we??

Quote:

Originally Posted by Biodiesel300TD

I'm not sure anyone is going to be able to tell you exactly how much vac each part of the system is supposed to have. An easier way to figure out if you have a leak is to pull vac on a particular system and see if it holds vac. If it doesn't, then move down that system until you find the leaking culprit.

You didn't say what year so we'll have to wing it.
http://www.peterschmid.com/vacuum/1980/617_950.jpg

The brake booster gets full vacuum, everything else is after the orifice. Like stated above. If it works it's good. The only thing that should have variable vacuum is the line going to the transmission modulator.

Danny

speedyspaceman · #7 12-31-2009, 12:43 PM

Thanks for all the replies. I used the attached diagram to confirm my connections and they were all correct. If someone would use that diagram to label (Maybe with Microsoft paint or someother drawing program) each tube and connection point with the correct vacuum maybe that would be easier to do. I appreciate all your help.

toomany MBZ · #8 12-31-2009, 01:05 PM

The biggest deal will be the transmission. You're looking for 20-25Hg in from the vacuum pump itself, that should go full strength to everywhere. The second nipple may be lower. Out of the VCV is where you measure the values.
The pic shows the transmission pressures. You have a 722.117

speedyspaceman · #9 12-31-2009, 01:34 PM

Should I measure that lower pressure through the whole second connection system or just the line that goes down to the tranny? How much exactly is optimal for that line? Sorry for being unsavy to the whole vacuum thing. This is my first vacuum problem. My car was stored for nearly 15 years, so there was very little wrong. Good news is I got to buy some new tools! Thanks

bmwpowere36m3 · #10 12-31-2009, 01:51 PM

Other than the vacuum for the transmission modulator, the "exact" amount of vacuum for each system is inconsequential (as long the systems operate, the exact amount of vacuum makes no difference).

So, what's the problem, what doesn't work?

You mention the first nipple on the brake booster line (closest to the front of the engine) doesn't read any vacuum and the second one does? Most likely it's clogged, get a 1/16" drill bit (by hand) and clear out the nipple. Re-test.

toomany MBZ · #11 12-31-2009, 02:17 PM

Quote:

Originally Posted by speedyspaceman

Should I measure that lower pressure through the whole second connection system or just the line that goes down to the tranny? How much exactly is optimal for that line? Sorry for being unsavy to the whole vacuum thing. This is my first vacuum problem. My car was stored for nearly 15 years, so there was very little wrong. Good news is I got to buy some new tools! Thanks

Brian Carlton walked me through the procedure, but it's long enough ago I can't remember exactly, but I'll venture a guess which would be run a "T" from the top of the green dashpot above the VCV that goes to the transmission to a gauge in the cabin, drive around and note readings.
EDIT: yes, you should be getting full vacuum off that first nipple.

Brian Carlton · #12 12-31-2009, 05:21 PM

Quote:

Originally Posted by speedyspaceman

This would be an amazing help for many people who are trying to diagnose their mis-shifting transmissions.

I haven't seen any symptoms of a mis-shifting transmission. If there are any symptoms, the OP would usually post them and we'd go forward from that point.

speedyspaceman · #13 12-31-2009, 07:10 PM

Don't let my lack of information fool you. I have a flaring tranny in all shifts but first to second. I am working my way from the vacuum pump backwards eliminating all possibilities on my way towards the tranny. I have replaced all the white vacuum valves, yellow lock valve, dashpot and am now measuring vacuum and I am unclear how much vacuum I should be having at each point optimally. Hence the inquiry. I am sure that many people would value a chart like the one I attached above with those labels on it for future reference, maybe even one for the 300D just for kicks also.

Brian Carlton · #14 12-31-2009, 07:22 PM

Quote:

Originally Posted by speedyspaceman

Don't let my lack of information fool you. I have a flaring tranny in all shifts but first to second. I am working my way from the vacuum pump backwards eliminating all possibilities on my way towards the tranny. I have replaced all the white vacuum valves, yellow lock valve, dashpot and am now measuring vacuum and I am unclear how much vacuum I should be having at each point optimally. Hence the inquiry. I am sure that many people would value a chart like the one I attached above with those labels on it for future reference, maybe even one for the 300D just for kicks also.

There is no chart required. The transmission is modulated by vacuum. The first thing to test is the vacuum that is going to the transmission. Connect a vacuum gauge with a T into the transmission line. Route it into the cabin so you can watch it while you drive.

Drive it in various modes at various pedal positions and report back with results. You probably have an issue with the vacuum control valve that results in too much vacuum to the transmission.