This is a thriller. I am totally glued... let me get some popcorn...

By the way... Great stuff Brain. I am learning a lot. Not even my problem but learning a lot. Thanks.

@cphilip - Hahaha, I hope the pictures are better educating you; I was planning on creating a DIY article (hence the photos) out of this thread because I bet I am not the only one who searched far and wide and found no DIY documentation on testing.

@Brian - cphilip is right, you are brilliant and I can not thank you enough for your time and patients on the matter. I will be purchasing a EGR Blocking plate from you on my next paycheck, yeaaa. =D

__________________
'87 300TD Estate (Panzer Wagon, Sold)
'95 E320 Estate (Sabertooth, Sold)
'94 E500 (Stark 1, For Sale)
'04 VW GTI (Rhino, Sold)
'12 VW GTI Autobahn (Shadow)

Don't thank me yet.........you've got to find that vacuum leak and then........hopefully.........the hard shifting problem goes away.

@Brian - Irregardless you have been invaluable to me already

__________________
'87 300TD Estate (Panzer Wagon, Sold)
'95 E320 Estate (Sabertooth, Sold)
'94 E500 (Stark 1, For Sale)
'04 VW GTI (Rhino, Sold)
'12 VW GTI Autobahn (Shadow)

I case it will help, here's a photo from an '87 300D:

__________________

Gone to the dark side

- Jeff

I have the Y, believe that it goes to the CCU as it goes through the firewall.

__________________

Gone to the dark side

- Jeff

Um.... have you verified that the two lines from the 5-way splitter, that go towards the engine (one to the VCV on the IP, the other into the passenger compartment) are not leaking? And verified the VCV is ok? If you put the ACC on full heat and do not get air out the footwell, and/or put ACC on full cold and do not get air out the center dash vents... you're probably dealing with a simple vacuum leak somewhere. BT, DT.

You might be chasing your tail with the amplifier, try testing at the source (vac pump) and working in (VCV, etc), instead of from the end (tranny modulator) and working out. Also make sure the rubber cap on the tranny modulator is not cracked, that can also cause a vacuum leak. And make sure the VCV on the side of the IP is adjusted per the FSM procedure (usually, this means it ends up right in the middle of the adjsutment range).


Oh yeah, two more things:

Mercedes Benz Transmission Diagnostics:
http://continentalimports.com/ser_ic20242.html

If you haven't seen this "tips & tricks" article yet on the 1987 300D/TD, you might want to peruse it:
http://www.w124performance.com/docs/mb/articles/124.1x3_buying_tips.txt

__________________
Dave
Boise, ID
Check out my website photos, documents, and movies!

Okay so I tested the VP and got like 20" and figured, great, that works lets take out the 5-way splitter. I removed the 5-Way Splitter and put in a Y to split to the two that are in use.

I then tapped into the line going from the Vacuum Amp to the Transmission after the Damper and started the car up... VACUUM! It sat half way between 5" and 10" (so like 7.5"?)

So I brought the MityVac into the car and drove around the block and let me tell you, I don't know if that is the correct amount of pressure I am suppose to have at that point but 3rd to 4th shifted so beautifully that I almost cried. hahaha oh man this is great stuff.

@Brian- I got a constant pressure half way between 5" and 10" no matter what throttle point and that number did not change during shifting. Is that what is suppose to happen?

I don't have my camera however I will snap pictures of my temp. replacement for the 5-way splitter; I figure it is a very low (and inexpensive) failing part but I am not complaining!

__________________
'87 300TD Estate (Panzer Wagon, Sold)
'95 E320 Estate (Sabertooth, Sold)
'94 E500 (Stark 1, For Sale)
'04 VW GTI (Rhino, Sold)
'12 VW GTI Autobahn (Shadow)

Ideally, you'd like about 10-12" vacuum at idle. This typically remains steady unless you get more than 1/2 way into the pedal...........then it will start to drop..........at about 3/4 pedal it will be down to 5"...........and at full pedal it should drop to less than 2".

If there is no change of reading no matter what the pedal position, further tests are necessary to determine the culprit. The tests will be identical to the previous tests where vacuum is measured at various points along the system.

@Brian - Okay I am game, should I test back between the VCV and where the 5-way splitter was located and see if I get 10"-12"?

__________________
'87 300TD Estate (Panzer Wagon, Sold)
'95 E320 Estate (Sabertooth, Sold)
'94 E500 (Stark 1, For Sale)
'04 VW GTI (Rhino, Sold)
'12 VW GTI Autobahn (Shadow)

Why not test the output of the VCV directly, and see if it varies with throttle input? There's even a test in the FSM for this, along with the procedure to set the VCV...

@Brian - Okay so I just did some testing and I am going to the Diagram (Page 6&7) as reference to best explain my results.

Tapping into the Supply Line going from the Vacuum Pump (67) to the VCV (65) I have just a hair over 20".

Tapping into the line that goes from the VCV (65) to the Vacuum Amplifier (123 VAC) I a hair over 20".

Tapping into the line that goes from the Vacuum Amplifier (123 VCV) to the Vacuum Amp Switchover Valve (Y29) I have ZERO.
- Which means that the Y going back to the VCV (65) which happens to be a black with red stripe hard vacuum line has ZERO as well.

Tapping into the Vacuum Amp (123 TRA) before/after the Damper (72) I get halfway between 5" and 10".

Where do I go from here?

@gsxr - I went from the Vacuum Pump backwards just for you

__________________
'87 300TD Estate (Panzer Wagon, Sold)
'95 E320 Estate (Sabertooth, Sold)
'94 E500 (Stark 1, For Sale)
'04 VW GTI (Rhino, Sold)
'12 VW GTI Autobahn (Shadow)

OK... Y29 is the "shift softener" soleniod. When the engine is cold, and Y29 is energized, it's supposed to send modulated vacuum (0-15") from the VCV to both the "VCV" port and the "PRE" port on the BFS (#123).

When the engine is warm, Y29 is not energized; then the "PRE" port is supposed to receive boost pressure from the ALDA branch fitting. The VCV port still receives modulated vacuum from the VCV. The idea is to only allow a full-hard shift when there is X-amount of boost present.

On top, "TRA" is easy enough, that's the output of the BFS to the tranny. And "VAC" is also self explanatory, it should receive full vacuum at all times, this is the input. The other two (PRE and VCV) are on the underside of the BFS (Blue Flying Saucer, in case you were wondering. )

On my cars, the shift softener setup makes it flare when cold. I disconnected that and it works fine (no harsh cold shifts, at least with synthetic ATF). On my '87, I removed Y29 and all the plumbing... it always receives boost pressure to the "PRE" fitting. Initially I just disconnected the electrical signal to Y29 which does the same thing, but I wanted to eliminate all the plumbing to clean things up.

Repeat this test. The result is not possible unless the VCV has totally failed.

The measurement must be on the line from the VCV to the VCV port on the bottom of the amplifier. If you measure the wrong line, you'll get 20" vacuum..........and I'm quite sure that's what happened.

I think you're right, Brian. The reading should be more like 15", dropping near zero as the throttle is opened all the way.