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transmission issues.
(85 300SD)
I have had the car for 4 weeks now. I had a boost issue at first, that has been solved. Since then the transmission has been shifting great 95% of the time. I spent a lot of time checking the vacuum system. Vacuum pump pressure 22, no leaks at the transmission modulator, no leaks on the line. Checked pretty much all of the other vacuum systems, brake booster, doors, ALDA line, boost line etc.. I cannot find anything wrong. The only system I have not checked is the climate control. Is there a way to isolate the entire system? Just want to run a test drive with the climate system bypassed. I think that by now I have read pretty much all the threads related to hard shifting. When the car is cold, it shifts great, after about 30 minutes or so I start to noticed occasional hard shifts, by the end of the day it's pretty much non stop, but always at low speed, if I step on it then it shifts fine. If I use 3rd, great shifting, in Drive it's a disaster. Seems to be shifting too soon. Don't know what to do next.... Any ideas? Thanks. F I adjusted the modulator already and no changes. |
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Bowden Cable? (so you're saying HOT fluid=harsh shifts?)
I ask your forgiveness for waxing pedantic...
These transmissions are kinda like Mathematics: A good strong,Known baseline (engine making proper Power/basic tranny adjust set) THEN adjustments are made in a sequenced progression [pressure gauge measurement feedback is of incredible value] Hopping Willy Nilly from what YOU THINK is needed, to the next perceived "Needed" adjustment, just moves you MILES from Your Successful accomplishment. stevebfl's tutorial:http://www.peachparts.com/Wikka/TransVacTune AND SMR's :It's CRITICAL... how you set your transmission's vacuum system on your diesel MBZ... Two threads the same title, but different authors and content. Bowden Cable
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'84 300SD sold 124.128 Last edited by compress ignite; 09-15-2009 at 01:00 AM. |
#3
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Search for Bowden Cable, K-1 Spring Kit, and B-2 Band replacement.
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Regards, Ian White 1995 E300 Diesel w124 OM606 2014 E550 w212 M278 biturbo 2001 BMW 740i E38 M62 (past) 1981 300SD w126 OM617 (past) |
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Quote:
My mechanic has been working on MBs for 30 years now. I am sure that he has a very extended knowledge of MB. However by reading these articles it seems to me that one should have a very specialized "MB trany" mechanic troubleshooting and fixing things up. I guess I'll have to find someone , somewhere in the Pacific NW. |
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1991 300CE Bowden Cable
This is an image of the bowden pressure cable arrangement on a 1991 300CE. Probably typical for any 300 during that time. Picture taken with the air cleaner removed. Bowden cable is attached to the throttle linkage and is directly behind the throttle body.
Using a 13mm wrench, turn the plastic yellow adjustment nut counter-clockwise when facing the vehicle to shift sooner, clockwise to shift later. The arrow and mark were not necessarily aligned when I had it where I wanted it. Be sure to inspect the vacuum line to the vacuum modulator for a tight fit while you're at it, but don't tug too hard or you will pull it loose from the transmission end and you will have to crawl under the car to reattach it. Please note: This car is new to me and I still tinkering with it and learning it, but I thought that this might be a start to show you what at least one bowden cable arrangement might look like. |
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x2, R+Ring these parts will make it seem like a new transmission. B2 failure does not sound like the problem in this situation. As always, just start with a fluid/filter change and make sure that the level is correct. From there, I would open up the bottom and check out the valve body, replace the springs and clean if necessary. Not really familiar on your transmission specifically, but it should be similar in many respects.
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TC Current stable: - 2004 Mazda RALLYWANKEL - 2007 Saturn sky redline - 2004 Explorer...under surgery. Past: 135i, GTI, 300E, 300SD, 300SD, Stealth |
#7
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Thanks guys for your help.
I gave up and sent the car to a local MB mechanic who came highly recommended for trany problem. Looks like my Transmission modulator was out of spec, was 4.6 and should have been 4.8 (the modulator is adjusted specifically to each transmission). Also adjusted the pressure at the vacuum amplifier/transducer to 17psi from 15psi and finally adjusted the bowden cable which was a bit to tight. Now the car is shifting really well, of course still have the typical firm shift if I let go of the accelerator at precisely the time at which the transmission shifts. Very happy, guess the transmission issue is resolved, now I need to concentrate on slight oil leak coming from the turbo... Thanks again.. F |
#8
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Quote:
Bowden cable, is this the adjustment Bowden cable... Not sure why they got jacked up like that.
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1992 300D 2.5T 249k - Parked with a bad transmission 1981 300SD 142k - Daily driver |
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