WHat is this thing? (126/603) - PeachParts Mercedes-Benz Forum

P.E.Haiges · #1 10-08-2007, 12:14 AM

On the driver's side on the inside front fender is a round, blue, plastic gizmo with 4 or more vacuum lines going to it.

What is it and what does it do?

P E H

Ara T. · #2 10-08-2007, 12:16 AM

Vacuum amplifier?

Brian Carlton · #3 10-08-2007, 12:17 AM

Vacuum amplifier.

Takes input signals from VCV, boost pressure, and vacuum and provides the vacuum signal to the transmission.

P.E.Haiges · #4 10-08-2007, 12:40 AM

Brian,

Some of the vacuum connections are not connected. Could this be why the transmission shifts so hard?

I'm away from home now and have no idea how to reconnect the loose vacuum lines. I will have to wait to I get home (3000 miles) to look at another 126 to see where everything goes.

P E H

Brian Carlton · #5 10-08-2007, 12:41 AM

Quote:

Originally Posted by P.E.Haiges

Brian,

Some of the vacuum connections are not connected. Could this be why the transmission shifts so hard?

I'm away from home now and have no idea how to reconnect the loose vacuum lines. I will have to wait to I get home (3000 miles) to look at another 126 to see where everything goes.

P E H

Yep, the trans is not getting any vacuum.

I can talk you through it if you have the time in the morning. There are only four hoses to connect...........boost pressure, vacuum, transmission, and VCV.

P.E.Haiges · #6 10-08-2007, 01:27 AM

Brian,

That would be great if we can get together on the time. I'm in AZ now, 3 hours earlier than NY. Would 10 or 11 AM be OK? I'm leaving for Vegas in the morning.

I can take puter to the car because I have a wireless connection here.

I bought a 2 foot piece of vacuum hose so I can make the connections.

P E H

Brian Carlton · #7 10-08-2007, 01:30 AM

Quote:

Originally Posted by P.E.Haiges

Brian,

That would be great if we can get together on the time. I'm in AZ now, 3 hours earlier than NY. Would 10 or 11 AM be OK? I'm leaving for Vegas in the morning.

I can take puter to the car because I have a wireless connection here.

P E H

Sure Paul, 10:00 is fine. Aren't you 2 hours earlier in AZ?

P.E.Haiges · #8 10-08-2007, 02:13 AM

Brian,

NO, 3 hours because AZ does not use Daylight Saving Time. AZ is 2 hours different from eastern time in standard time.

Do U have Yahoo Messenger (YM). Instant messaging would work well. I don't have a cell phone.

I'll send my Yahoo handle by PM if U have YM.

P E H

Brian Carlton · #9 10-08-2007, 09:41 AM

Quote:

Originally Posted by P.E.Haiges

Brian,

NO, 3 hours because AZ does not use Daylight Saving Time. AZ is 2 hours different from eastern time in standard time.

Do U have Yahoo Messenger (YM). Instant messaging would work well. I don't have a cell phone.

I'll send my Yahoo handle by PM if U have YM.

P E H

Paul,

Yep, I can use YM. Send me your address and we'll sort it out.

P.E.Haiges · #10 10-10-2007, 06:36 AM

Brian,

After a 300 + mile run from Phoenix to Vegas, the transmission shifts softer on upshifts but it still jerks when downshifting when coming to a stop.

I want to tell all the folks here on the website how Brian helped me straighten out the vacuum connections on my transmission Vacuum Amplifier that was AFU from the PO.

Brian spent 1 1/2 hours on line using Yahoo messenger to solve my problem because I was away from home and had no reference material or other car for comparrison.

Thanks again Brian.

P E H

Brian Carlton · #11 10-10-2007, 10:04 AM

Quote:

Originally Posted by P.E.Haiges

Brian,

After a 300 + mile run from Phoenix to Vegas, the transmission shifts softer on upshifts but it still jerks when downshifting when coming to a stop.

I want to tell all the folks here on the website how Brian helped me straighten out the vacuum connections on my transmission Vacuum Amplifier that was AVU from the PO.

Brian spent 1 1/2 hours on line using Yahoo messenger to solve my problem because I was away from home and had no reference material or other car for compareson.

Thanks again Brian.

P E H

Glad it's improved for you Paul. It still shows that it needs more vacuum. We can straighten it out when you get home and have a Mityvac to see what's going on there.

Enjoy the remainder of the trip.

Ken300D · #12 10-10-2007, 01:09 PM

Maybe you can just run straight vacuum to the transmission modulator. It will shift smoothly up and down then, you just need to be easy on it with the power as if you were Granny driving it, so you don't wear the clutch bands any more than necessary.

Accelerate no faster than a 240D automatic and you should be OK that way.

Ken300D

P.E.Haiges · #13 10-10-2007, 08:14 PM

Ken300D,

I'd be afraid to do that. I unknowingly connected full vacuum to a '80 300SD automatic transmission by putting the tri-connector to the vacuuum valve on wrong and I ruined the transmission.

P E H

rgp123 · #14 10-11-2007, 03:28 AM

Did you adjust the volume set screw in the bottom of the amplifier? My 87 SDL had some issues that were resolved there. Take the amp loose from the fender and turn it upside down. You will see the adjustment there.

Ken300D · #15 10-11-2007, 07:15 AM

Wow - did not realize the level of risk involved. But again I have never myself run a diesel with full vacuum on the transmission modulator. I have run with no vacuum, and that makes for very abrupt shifting. That's how the differential became worn out on my 1982 300D due to the shifting stress. Somehow the transmission survived long enough for me to purchase the car and get the vacuum hookup corrected. Now it shifts a little softer than my other cars, but I baby it and the situation is sure better for the car.

Did you buy another car and are in the process of driving it home?

Ken300D