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  #76  
Old 10-22-2006, 06:44 PM
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That's great news, and proves once again...

... proves what I believe Steve Brockton once said... that the lack of understanding about these MBZ Engine/Tranny vacuum control systems [even among mechanics in their own business]... this common lack of understanding has probably sold a lot of transmission rebuilds !

Now that you are into the fine tuning stage for the tranny, keep in mind that the little green plastic "DashPot" [aka = surge damper] that sits just above the VCV also has a significant impact on the shifts... especially the 1-2 shift. I have added DashPots to both of our 1980 models [they were not OEM on pre-1981 models] and it really makes a difference. So remember that you are adjust ing the modulator on the tranny more for the 2-3 and 3-4 shifts and the DashPot is more for 1-2 shift and to a lesser degree 2-3 and 3-4 shifts. Because of the interaction of the DashPot and Modulator, I'm even toying with the idea of figuring out how to adjust a DashPot by drilling a small hole in the chamber and then partially filling it with caulk or something that would reduce the chamber's capacity and then harden and reseal the chamber... this so that I could ignore the 1-2 shifts when adjusting the Modulator and then, IF NEEDED, install and adjust primarily the 1-2 shifts by adjusting the volume as I just described. The objective is to have all shifts to be firm but not like a "kick in the rear"!
Great news - except the notion that you have a full-fledged CA car. I would ask that eventually you give this THREAD a final summary on your project with this problem after you have made you final fine tuning!
Regards,


Last edited by Bill Wood; 03-21-2009 at 09:34 PM.
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  #77  
Old 10-22-2006, 08:59 PM
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Quote:
Originally Posted by patman View Post
Brian, you da man!!!

I did just as you explained and it's shifting without flaring in any gear.
Most excellent.

Help is what we do here!
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  #78  
Old 10-22-2006, 11:12 PM
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Gentlemen,
I disconnected the lines to the black box, and connected the t's. Made a difference in the shifting. But then the engine would not shut off. Thoughts?
Thanks!
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2004 E500 4matic; 72,000mi
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  #79  
Old 10-22-2006, 11:19 PM
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Originally Posted by Wallknight View Post
Gentlemen,
I disconnected the lines to the black box, and connected the t's. Made a difference in the shifting. But then the engine would not shut off. Thoughts?
Thanks!
You left one of the vacuum lines open. When you connected the T's, you made a mistake with the connections. Or, you connected a vacuum line to one of the vent lines and the system has no vacuum.
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  #80  
Old 10-22-2006, 11:48 PM
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my '83 sd skips 2nd gear when not flooring the pedal... what do I need to adjust again? and, where can I get a 5 speed manual for this car? doing 60 at 3000 RPM seems kinda weird, coming from europe.
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  #81  
Old 10-23-2006, 12:29 AM
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Dashpots and shifting

Samuel,
Thanks for the pointers on the dashpots. I have the green one and I didn't find any orifices on the vacuum lines. I will use the information you posted in the fine tuning process. It is especially important because the 1-2 shift is "rugged", the 2-3 shift is too soon and 3-4 is okay. The 2-3 follows the 1-2 by a second or two unless you are laying down the throttle.

I will post the summary, but it will be a couple of weeks before I get my hands on the car again. Between work, camping, household chores and my daughter I won't get 5 minutes on it for at least 2 weeks. I'm thrilled to have it in it's current state for now.

This was suppose to be my car and I let her drive it while she saves some $$$ for her car. She has fallen in love with it. The worst thing I could do now is replace the Becker now.
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  #82  
Old 10-23-2006, 12:35 AM
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One thing I forgot

While pumping up (or maybe pumping out") the VCV to 14, I noticed that the system leaked. I placed the pump above the dashpot. It went at a rate that reduced vacuum from 14 to 13 in about 10 seconds and the trend continued to 0. The vacuum holds steady while measuring above the dashpot at idle. If I press the brake I lose vacuum.

Do you see danger signs?
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  #83  
Old 10-23-2006, 08:29 AM
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Quote:
Originally Posted by patman View Post
While pumping up (or maybe pumping out") the VCV to 14, I noticed that the system leaked. I placed the pump above the dashpot. It went at a rate that reduced vacuum from 14 to 13 in about 10 seconds and the trend continued to 0.
That's the modulator or the connections to the modulator leaking. The amount of the leak is not significant.
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  #84  
Old 10-23-2006, 09:00 AM
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Another Good Vacuum Thread.....

Folks,

I respectfully request that a "Vacuum" section be created in either the DIY Section (DIY Links by Parts Category), or as a stickey at the top of the Diesel Forum.

When I had my initial Vacuum Problems, which I solved, and thus corrected my transmission shifting problems as an added benefit...I did not find, nor was I directed to that perticular article....instead everyone referred to the "Blue Flying Saucer Like Thingy"(Vacuum Modulator).....and I had even asked what the screw adjustment did.....so if there were a "Vacuum Section" a person could find some of this info a bit more easilly....this particular article should also be within the existing "Transmission" section.....and it should get many stars for it's content....

SB
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Diesels:
'85 300D, "Max, Blue Benz", 155K, 27.0 MPG
'84 190D 2.2, "Eva, Brown Benz", 142K, 40.2 MPG
'77 240D (parts car)
'67 Eicher ES 202 Tractor "Otto" (2cyl, Air Cooled, 30HP)
Gassers:
'94 Ford F-150, "Henry", 170K (300 Six) 17.5 MPG
'85 190E 2.3, 148K....Parts Car
'58 Dodge W300M Powerwagon (Flat Fenders) Less than 10 MPG
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  #85  
Old 10-23-2006, 09:04 AM
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Quote:
Originally Posted by Shorebilly View Post
....instead everyone referred to the "Blue Flying Saucer Like Thingy"(Vacuum Modulator).....
If they referred you to the blue flying saucer, then the device is properly called the vacuum amplifier or the vacuum transducer........depending on the source.

The vacuum modulator is the device on the transmission that accepts the vaccum from the amplifier. The modulator can be adjusted to provide additional pressure internally to the transmission.
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  #86  
Old 10-23-2006, 09:37 PM
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Thanks Brian,
Went back, took the t's out. Now it shuts off, and shifts like a car, not a 30-06! So many fun little secrets with these cars!
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  #87  
Old 10-23-2006, 09:52 PM
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Quote:
Originally Posted by Wallknight View Post
Thanks Brian,
Went back, took the t's out. Now it shuts off, and shifts like a car, not a 30-06! So many fun little secrets with these cars!
Good job.

You have to be careful when you remove those T's. If you err, all kinds of bad things happen.
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  #88  
Old 10-24-2006, 03:02 AM
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'84 300CD Vacuum Transmission Problem - Slips in 1st

Greetings,

I am troubleshooting my '84 300CD. I have been experiencing vacuum problems with the brakes, door locks, engine shut-off, and egr valve. The transmission started slipping this week, prompting me to fix the vacuum problems (as if the brakes and shut-off weren't enough). The transmission started slipping in 1st gear, mostly when starting from stop. It also slips uphill very occasionally. The slipping in 1st gear is pretty bad. I was unable to get it up on the ramps today. Other gears seem fine, and it has always shifted smoothly.

I have currently fixed the brakes and engine shut-off by removing the door locks and egr from the vacuum system (these two circuits had gross leaks).

After reading this thread, I found the following:
1. Vacuum Pump creates ~22 mmHg
2. Door Lock Circuit has leaks (troubleshoot later)
3. EGR vacuum valve leaks (troubleshoot later)
4. All other lines hold vacuum
5. Tested Vacuum after the VCV on the IP (towards the tranny) 15mmHg at idle.
6. When increasing the throttle, vacuum sits around 10mmHg and doesnt drop below 10------or--------
7. When really punching the throttle, vacuum drops quickly to zero.
8. The irratic difference in vacuum measured at the Tranny Vacuum Line leads me to believe the Vacuum Control Valve is not funtioning properly.
9. When I removed the vacuum from the tranny altogether, she still slipped in first, no real change.

Should I start adjusting/checking/relacing the VCV?

Is it time to start suspecting internal tranny mechanical problems??

Thanks for your help,

Brandon
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'82 VW Vanagon Diesel (Butter Bean), 1.9l Turbo Engine 5K, Chassis 130K, Vegetable Oil Vehicle - Owned 2 Years
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  #89  
Old 10-24-2006, 05:56 AM
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Still requesting a Vacuum Thread in DIY......

Quote:
Originally Posted by Brian Carlton View Post
If they referred you to the blue flying saucer, then the device is properly called the vacuum amplifier or the vacuum transducer........depending on the source.

The vacuum modulator is the device on the transmission that accepts the vaccum from the amplifier. The modulator can be adjusted to provide additional pressure internally to the transmission.
G'mornin',

Mr. Carleton, As I said, I located my problem, and learned what all the various devices did.

The meat of my previous post here, and several others is.....

I see a need for a "Vacuum" thread in the DIY Links by Parts Category section of this website.....I had some vacuum problems, I managed to resolve them with some excellent help from the folks here in Diesel Forum. However, this topic keeps popping up, and the answers keep getting repeated...over and over....

IF the moderators would take a bit of time, and begin a "Vacuum Problems" section someplace then it would make life a bit easier for the next person to have one of the problems like....
Engine Won't Shut Off
Transmission Shifts Hard/Oddly
I Hear a Hissing Noise
Climate Control Has Lost Its Mind
and so forth.......

I apologize if I am out of line here......just think a "Vacuum Thread" in DIY would make life easier for those working all around a complex MB system.

If I had read tis thread, a month ago....it would have made life a bit easier....

Also, I take this opportunity to thank all who helped me at that time, again!!

Thanx,
Shorebilly
__________________

Diesels:
'85 300D, "Max, Blue Benz", 155K, 27.0 MPG
'84 190D 2.2, "Eva, Brown Benz", 142K, 40.2 MPG
'77 240D (parts car)
'67 Eicher ES 202 Tractor "Otto" (2cyl, Air Cooled, 30HP)
Gassers:
'94 Ford F-150, "Henry", 170K (300 Six) 17.5 MPG
'85 190E 2.3, 148K....Parts Car
'58 Dodge W300M Powerwagon (Flat Fenders) Less than 10 MPG
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  #90  
Old 10-25-2006, 02:35 AM
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Welcome to what I call our " Tranny Vacuum THREAD"...

Quote:
Originally Posted by TooManyDiesels View Post
Greetings - I am troubleshooting my '84 300CD. I have been experiencing vacuum problems with the brakes, door locks, engine shut-off, and egr valve. The transmission started slipping this week, prompting me to fix the vacuum problems (as if the brakes and shut-off weren't enough). The transmission started slipping in 1st gear, mostly when starting from stop. It also slips uphill very occasionally. The slipping in 1st gear is pretty bad. I was unable to get it up on the ramps today. Other gears seem fine, and it has always shifted smoothly.
I have currently fixed the brakes and engine shut-off by removing the door locks and egr from the vacuum system (these two circuits had gross leaks).
After reading this thread, I found the following:
1. Vacuum Pump creates ~22 mmHg
2. Door Lock Circuit has leaks (troubleshoot later)
3. EGR vacuum valve leaks (troubleshoot later)
4. All other lines hold vacuum
5. Tested Vacuum after the VCV on the IP (towards the tranny) 15mmHg at idle.
6. When increasing the throttle, vacuum sits around 10mmHg and doesnt drop below 10------or--------
7. When really punching the throttle, vacuum drops quickly to zero.
8. The irratic difference in vacuum measured at the Tranny Vacuum Line leads me to believe the Vacuum Control Valve is not funtioning properly.
9. When I removed the vacuum from the tranny altogether, she still slipped in first, no real change.
Should I start adjusting/checking/relacing the VCV?
Is it time to start suspecting internal tranny mechanical problems??
Thanks for your help - Brandon
Brandon – For clarification purposes please let me know IF my MB reference is NOT correct when it tells me that your “1984 300CD” is more completely known as a W123.153 chassis 300CD Turbodiesel and that she has the same 617.952 engine or same the car came with.

Where are you just there in the W. of Sonoma County… up near the Russian River? Our 1980 300D came from a PO in Healdsburg!

From your 1st POST it’s evident that you have done your homework...and Believe me when I say that your having done that homework makes it a lot easier for those who monitor this FORUM/THREAD to give you a helping hand. I will try to HELP too but let me say that I’m off to Italy next Wednesday and will be gone until Thanksgiving so let's see if we can get you well on your way to resolving your problems with what I presume is a beautiful CD coupe. With the stable of diesels you have, I don’t think it would be fair to call you a “newbie” assuming you don't have the $$$ to pay others to maintain these vehicles... this despite this being your very 1st POST on MercedesShop.Com's FORUM.
Now let me address your well defined problem as best my experience allows... and let me say up front that I hope Brian Carlton will chime in here soon… but until he does, let me say that based upon my experience with the VcV(s), before you make any adjustments, try these tests in (2) and (3) below first:
(1) First I would disconnect the mechanical linkage between the VcV and the IP.
(2) Then with the engine idling and your vacuum gauge measuring around the 15mmHg you reported in your POST, I would manually vary the VcV while observing the gauge. This way you don’t have to run the RPM up on the engine since you will only be testing the VcV. Vary the VcV slowly from what you know is the idle position up to the max throttle position and observe the vacuum gauge [installed on a “T” so that you are reading the vacuum that the tranny’s vacuum modulator sees]. What you are looking for is a smooth transition as a result of the bleeding down of the vacuum by the VcV. If you see any abrupt changes this MIGHT indicate the VcV is beginning to fail or possibly only gooped up with dirt/grime.
(3) Also while you are configured as in (2) testing the VcV, also try the rapid throttling of the VcV and see if you get the same dropping to zero effect you did when everything was hooked up normal. Either way I think the results of these two tests (2) and this (3) will tell us something.
I have presumed you have your own combo hand vacuum pump and gauge.

Oh yes, for reference purposes:
IF your car is "Federal" the vacuum diagram at this link should be yours:
http://www.peterschmid.com/vacuum/1977_1985/617_95/1981_1984.jpg
IF your car is "California" the vacuum diagram at this link should be yours:
http://www.peterschmid.com/vacuum/1977_1985/617_95/1984_1985.jpg
Regards,


Last edited by Bill Wood; 03-21-2009 at 09:35 PM.
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