Greetings,

I have a '90 300D, 2.5L Turbo. It's a nice car. I've had it about 6 months. So far I've done the wastegate swap, pulled the dash and replaced the vacuum actuators, pulled all of the vacuum devices by the turbo for the wastegate, EGR and flapper (is that the ARV?), pulled the blue flying saucer, properly set the VCV and have good system vacuum.

The previous owner had the transmission modulator replaced. I assume when the mechanic installed it he kept on increasing the pressure until there was no flaring. However, with the removal of un-needed devices and properly (hopefully) setting up and maintaining the engine vacuum's system the transmission modulator vacuum appears to be much too high.

I have backed the adjustment valve off about 3/4 of a turn. The abruptness of the shifts has decreased but still does not seem correct. I owned a w123 for 15 years and have driven other w123 and w124 so have some sense of how the tranny should behave in these vehicles.

The mod pressure is still too high. Is there any potential damage that can occur with me decreasing it further?

My understanding of the blue flying saucer is that it is designed to smooth the shifts. I may need to reinstall it. Any comments on the BFS and if (and how) it can be adjusted.

Thanks.

TGD

As a generic answer until some expert posts....
at some point of low pressure you could be slowing down the engagement of the clutches..
which would lead to very fast wear on them....
There is a great thread on auto trans... although I do not know if it applies to as late a car as you own....
One of the moderators and trans expert wrote it.. can not think of his name..
OH.. Steve.... Brotherton.... I think...

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

I have heard only good things about Steve Brotherton
the guy owns continental imports in gainsville florida
http://www.continentalimports.com/

search stevebl for his posts

here is a link for that article
look under magazine articles
http://www.continentalimports.com/ser_index.html

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I use to live in Gainesville, FL which is where Steve's shop was located (may still be - I don't know).

I've had good and bad experiences at his shop but I do not question his technical skill.

So I'd pay attention to what he says but would have some concern if his shop worked on my car.

When I last saw him, which has been quite a while, he had some health difficulties which may be why he was not on top of his people like he use to be.

Going back to low modulator pressure I recall this statement from a prior thread -

MB has specifications for modulator pressure but after 20 years and 250,000 KM it must be adjusted by how it performs and not be setting at a specific number. If that is correct than my tranny shifts much better at this lower pressure & I would like to know if I should have concerns if I lower it some more?

I'm also interested if anyone has an opinion about restoring the BFS. I think it was a post by GSXR who first suggested removing the BFS.

I just spent a while diagnosing a terminal 3-4 flare in my 87 190dt. I tried bypassing the BFS and found that the shifts were somewhat more crudely controlled. After I installed a rebuilt trans I hooked up the BFS again and find I prefer it this way. I would suggest restoring the BFS and increasing the mod pressure. In my opinion this will give better shifting for a greater percentage of the time. Some may prefer the harder shifts but I find it sometimes shifted real hard when I wasn't expecting it to so that is why I went back to using the BFS. Cheers Dan

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It's always something simple
91 300D 603.960 (from japan) 194K
92 Toyota Diesel Landcruiser HDJ81-t 116K
02 Golf TDI new head courtesy of PO
87 300D
97 BMW 525 TDS Wagon 5spd
bunch of Onan and other diesel generators

Thanks Dan,

I think I will restore the BFS and find out if I prefer it.

Stuart

There is an adjustment on the BFS as well, bottom side

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