PeachParts Mercedes-Benz Forum

PeachParts Mercedes-Benz Forum (
-   Tech Help (
-   -   Pedal 'Lite' shifting... (

Levon's 123 11-19-2005 03:32 PM

Pedal 'Lite' shifting...
Hello everyone, I am a little miffed tuning my vacuum system on my transmission. I paid someone else to adjust my valves. What a mistake! Anyway, now I have the hoses hooked up properly on my 1984 300turbodiesel - I can really only shift when I take my foot off the throttle. I can shift into 2nd at 3000 rpm, and 3rd at 3500 with my foot down, but it will shift fairly well at desired rpm's if I take my foot off the throttle. I seem to have the correct amount of vacuum in all the right places, any ideas where I should look next? ~Levon~

jbaj007 11-19-2005 03:54 PM

Check that the Bowden cable adj. hex got back in its slot on the linkage on top of the valve cover.

Levon's 123 11-19-2005 04:10 PM

Been there, done that - I have it set so it will shift nice at low rpm's - if I take my foot off the throttle...~Levon~

C32AMG 11-19-2005 10:41 PM

If you have to back off the pedal to make the transmission shift the Bowden cable is too tight and or you still have a vacuum problem.

You can do simple diagnostic test that will confirm if it is vacuum related. Attach a vacuum gauge to the modulator vacuum line. On a healthy engine at idle you should see a steady reading of 17 to 21 inches of vacuum. At WOT, just step on the gas pedal and release it, the needle on the gauge should drop immediately with no lag to 5 or less and when released the needle should quickly recover to its idle reading. If it does not recover and or if there is a read of more then 5 inches at WOT you have vacuum problem, a collapse hose or boost in the line. Bad switch over valve, lines not routed right, bad or out of adjustment vacuum proportioning valve if you model car has one. do a search for more help.

Craig 11-19-2005 10:50 PM

It still sounds like the Bowden cable is too tight. If you have to lift the throttle to make it upshift, I doubt it is the vacuum. Try loosening the cable just a little more and see what happens.

Levon's 123 11-21-2005 06:50 PM

You guys are great...
Levon here - You guy's are great! it was the Bowden Cable. There were a couple things going on however - this may help someone - The first thing I checked was the Bowden Cable. It didn't seem to matter much where it was set - it was apparently just adjusting the 'kickdown'... A friend told me a week ago he thought it was sticky, so I pulled back the rubber boot and hosed it down every other day with liquid teflon - as I used the car, the cable became well lubricated. I suppose after 20 years, a cable can get sticky... Meanwhile, I kept working on the vacuum system. After getting your feedback 2 nights ago, I revisited the Bowden Cable adjustment, and <BINGO!> It works like a new Mercedes! So before adjusting the Bowden Cable, make sure the cable isn't sticking...Thanks guys, let me know if I can help you on your cars!!! ~Levon~

Craig 11-21-2005 08:40 PM

Glad it's working, good tip on lubricating the cable.

All times are GMT -4. The time now is 08:17 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website