It's CRITICAL... how you set your transmission's vacuum system on your diesel MBZ... - Page 2 - PeachParts Mercedes-Benz Forum

Jmana · #16 07-11-2006, 03:28 PM

I don't know how it is on your car, but on mine the pink pod was accessible once I had the climate control system out. It's way back in there towards the upper right. I am sure there are other pods that were bad, but for some reason that single pod's vacuum had a significant effect on the shifting of the tranny.

miner · #17 07-11-2006, 04:00 PM

Quote:

Originally Posted by Brian Carlton

If I didn't mean it, I wouldn't have said it.

They are referred to as 3-2 valves and the vacuum setup on an '84 is different than yours. He can remove everything that goes to the black box.

You can't.

Yes. I did this. After being persuaded by an earlier discussion with Brian I think. It didn't adversely affect the shifts at all. But I can't go so far as to say that I have tested the vacuum levels before and after and found them to be the same. I DO have the correct schematic for my vacuum system and it is hooked up right (minus the EGR removal). Also, I hunted down all vacuum leaks too so it is a tight system now (there was a huge leak in the line to the trunk actuator).

What has me puzzled is that, when in stock configuration I had that weird behaviour I mentioned above. I could attach some pictures, but actually, that was the time I discovered a bb in my line to the transmission. I have since fixed that (made shifts so much better). So I will go test the setup I have now and make sure it behaves like you guys say at idle and under throttle.

Thanks

sailor15015 · #18 07-11-2006, 06:50 PM

Where did you get all those different orifices? The dealer? Thanks and good write-up.

engatwork · #19 07-11-2006, 07:30 PM

Thanks for providing the part numbers for the various orifices

. I typically just swap them out until I get the shift I want.

scoodidabop · #20 07-11-2006, 07:54 PM

Yeah, none of my vents open or close at all... I bet this is the heart of my woes. And probably the fact that the little bushing that are in the black box on the engine head are worn to nubs.

Brian Carlton · #21 07-11-2006, 08:03 PM

Quote:

Originally Posted by scoodidabop

.. I bet this is the heart of my woes. And probably the fact that the little bushing that are in the black box on the engine head are worn to nubs.

See post #8.

It applies to you.......as well.

dhbecker · #22 07-11-2006, 09:00 PM

I thought I might add my experience to this tale. Three years ago I had a remanufactured engine installed in my '82 240D @ 375,000 miles by an independent shop in Madison, WI. The engine was from an MB dealer, and had been shipped from Berlin. I spent a bundle when all was done. But this car was originally for CA with no rust and original paint in good condition, etc. The transmission had been replaced @ 200,000 miles. When I got my car back, the transmission "flared" between gears and the kickdown switch didn't work (as it turned out, a good thing initially for engine break-in). I took the car back to the shop where I had been having it serviced for ten years, and they said I needed a new transmission and that there were no adjustments possible on the transmission. They had already had trouble getting the transmission to shift, didn't know what to do (called me up and asked if I had any manuals!) but finally compared the internal hook-ups in the "black box" to another 240D that came into the garage, getting it to work. But no resolution on the shift flaring. Funny, because it had worked fine with the old engine. I drove it for 5,000 miles manually shifting between gears to avoid the flaring, while trying to decide what to do, and looking for further information.

Thanks to this forum, I read the Brotherton article and others, and called that business in Florida. I was directed to an independent MB mechanic in Des Moines, Iowa. I live in the Madison, WI area, but did not have confidence in the Madison MB dealer, where I previously had a disappointing service experience. I called the mechanic in Des Moines, explained the problem, and he said "I can fix it - I trained on the 240D 20 years ago!" I drove to Des Moines and the mechanic lost no time in quickly fixing it - checking over the vacumn lines and basically adjusting the modulator on the transmission (which I didn't know existed at the time). Cost: $120. I drove home with the transmission shifting better than it had before. Good thing I got a second opinion. The shop in Madison wanted to sell me a rebuilt trans for over $2,000, and I'll never know whether they were aware of the adjustment of the trans or not. I don't go there anymore.

I now have 396,000 miles on the car, the engine requires no oil between changes (maybe because of my careful break-in), and the transmission is still working just fine. I still have a problem with confidence in mechanics. I had the engine's first valve adjustment at the Madison MB dealer @ 15,000 miles. The service advisor assured me he had two mechanices qualified for my car. The mechanic was a young man who replaced the old valve cover gasket (none in stock) which now permits a faint oil leak around the cover base; lost the plastic retainer on the throttle for the idle adjustment cable, and left the breather hose from the valve cover disconnected. Maybe I will have to go back to Des Moines for further service...

Samuel M. Ross · #23 07-11-2006, 09:57 PM

"dhbecker" - It sounds to me like by now you should be motivated to roll up your sleeves and do some of this stuff yourself!

"sailor15015" - Yes, the dealer... at least those that I did not have. Your simple "Thanks..." means a lot !

"miner" - If you haven't invested in a " Mighty Vac " yet, do so... for a simple vacuum gage is limited where the hand vacuum pump is so useful testing devices with diaphrams and when looking for leaks in lines you have plugged at the other end. I have raised a few eyebrows driving around with my Mighty Vac wedged between my wipers and windshield!

Back on what to look for with your tranny vacuum. First, use a "T" to hook your Mighty Vac to the line just where it leaves the engine compartment and dives down to the tranny OR if you have extra rigid vacuum line sections and connectors, you could even "T-off" and measure the vacuum right were the line enters the vacuum modulator on the tranny. I read this somewhere!

What you want to see on your gage is a smooth transition from the first vacuum reading....... all the way down to or at least nearly to "zero". Again, if it does not go down that far, then this is an indication that you need to either:
(a) reduce the vacuum back towards the vacuum pump with a smaller orifice [my recommendation] OR
(b) increase the "bleeding" effect by adjusting the Vacuum Control Valve [VCV] that sits on your Injection Pump [IP]. I've looked at the inside of three of these and NOT all are adjustible. The PeterSchmid.Com WebSite has 8 pages of instructions on the procedures and special equipment for performing this task!

Let us know what your test reveals about how the vacuum fluctuates downward.

"scoodidabop " - The last thing you should feel from participating in this FORUM/THREAD is "stupid". The only bad question is the one you fail to ask! I for one will give you all the help I can... either ON the THREAD or OFF if that is warranted! Did you understand Brian's reference to " See post #8 " ?

==========================================

You know when I see terms like "pink pod" when talking about what is affectionately referred to as the "Environmental" system... this makes me cring when thinking about tackling this "broken" system on my Son's 300D. But everything in it's own time. At least he has heat and defog/defrost for the front window!

Chou,

Sam

PanzerSD · #24 07-12-2006, 02:58 AM

ok, so my 80 300SD doesn't have any special doodads that control EGR or ANY emissions control devices, all I have is that little green dashpot on my VCV....

the car was shipped sans emissions control stuff......

Samuel M. Ross · #25 07-12-2006, 09:31 AM

It's a nice photo of your engine compartment. Is that green thingy there your "DashPOT"... aka " Surge Damper " aka " Vacuum Damper "? These are all the different names I have seen used for this vacuum component, and I'm a relative "newbie"!

This brings up a point that has stuck with me as I have had the bad experience of these tranny vacuum control SYSTEMS... namely that there are so many different names being used for the same parts. It's no wonder we often get confused. Thus my strong preference to ask people to first identify the specific diagram or "schematic" from the 30+ different ones at the PeterSchmid.Com WebSite. Do you want to see one that I would not even wish on Brian!? Take a look at this "SCHEMATIC":

http://www.peterschmid.com/vacuum/1977_1985/617_95/1985_cal.jpg

Yes, this baby is a 1985 model fr#&*!@ing "California" car. Thank God my Father-in-Law's 85 is from Oregon! This vacuum SYSTEM not only has a "DashPot"... it has two of them... and a "SwitchOver Valve, Vacuum Transducer" and OH yes just for giggles, a "SwitchOver Valve, Boost Pressure Aneroid". And what the heck is this foreboding thing they call the " Control Unit ". Is that synonymous with "computer"?

The "Deutch" engineers must have just been in the midst of their first crack cocaine party when they designed this “SYSTEM”. I wonder if any of these are still out there and “functioning properly”. Serioiusly, it's no wonder they have gone away from such systems in favor of two and three computers! I challenge anyone to come up with a reference that logically explains what all of these “gizmos” does in the grand scheme of telling the tranny how to shift!

I enjoy a good challenge just as many of you do but for a daily driving vehicle my preference a simple non-turbo 240D!

Sorry about that "Got_The-Benz"...
you deserved better...
do you have a question?,
Sam

PanzerSD · #26 07-12-2006, 09:36 AM

Uhhh.. not really, just a little curious what the different colored "dashpots" would do for my car...but yeah, we have an 85 SD at my shop, and it also has (or had) two of those green things...

Samuel M. Ross · #27 07-12-2006, 09:56 AM

for it's my understanding that they serve much the same purpose as shock absorbers do for our suspension systems... they [dashpost] keep the VCV from bleeding off the "tranny control system's" vacuum too quickly.

Before I experienced my MBZ vacuum system " Epiphany " I was even thinking of putting one under my 240D's hood. But now I've been "reborn"... it's the simple life for me. I'm putting "bebes" [sp?] in any and all vacuum lines I see... and some day I want to see the clean lines of my 616 engine's valve cover with nothing perched on its head !

I'm getting silly... time for me to go !

Sam

Maroon 300D · #28 07-12-2006, 11:27 AM

Quote:

Originally Posted by Samuel M. Ross

.... Do you want to see one that I would not even wish on Brian!? Take a look at this "SCHEMATIC":

http://www.peterschmid.com/vacuum/1977_1985/617_95/1985_cal.jpg

Yes, this baby is a 1985 model fr#&*!@ing "California" car. Thank God my Father-in-Law's 85 is from Oregon! This vacuum SYSTEM not only has a "DashPot"... it has two of them... and a "SwitchOver Valve, Vacuum Transducer" and OH yes just for giggles, a "SwitchOver Valve, Boost Pressure Aneroid". And what the heck is this foreboding thing they call the " Control Unit ". Is that synonymous with "computer"?

The "Deutch" engineers must have just been in the midst of their first crack cocaine party when they designed this “SYSTEM”. I wonder if any of these are still out there and “functioning properly”. Serioiusly, it's no wonder they have gone away from such systems in favor of two and three computers! I challenge anyone to come up with a reference that logically explains what all of these “gizmos” does in the grand scheme of telling the tranny how to shift!

Sam

Thank you, Sam, for feeling my pain.

Other than a leak in my climate control system, though, I believe mine is functioning properly. It's clearly taken some maintenance, though. Most of the vac parts are new and the car was regularly serviced by the dealer from '92 to about '03.

I hope to figure out exactly what all those gizmos do one day. I'll have to know so I can figure out what's wrong when things start breaking down. I'm thinking I might have to write a letter to an old MB engineer, though - if any of them survived their alleged crack addiction, that is.

I never thought much about the 'control unit.' Looking at the diagram I'm not sure exactly where it is under the hood. Now I'm curious...research time...

P.S., thanks for the info. Jmana!

Jmana · #29 07-12-2006, 02:27 PM

Sure, anytime! Just let me know if it helps your shifting problem as much as it did mine. I don't know why the climate system vacuum would be interconnected to the transmission vacuum, but I know for a fact that it is somehow. If you would have driven my car before I plugged that line, you'd think the rear end was going to fall off when the car shifted, and it acted like it had no idea at what rpm to shift at. Now it's smoother than most cars that I have driven. And the only thing I did was plug that one line. On my 87 I went to the vacuum manifold for it's climate system, tested all the hoses going into the manifold with a mitivac, and found a leaky pod, so I just took a piece of plastic wrap and put it over the nipple, and plugged the hose back in, so that's another way to do it without having to access the pod itself.

dhbecker · #30 07-12-2006, 08:17 PM

Quote:

Originally Posted by Samuel M. Ross

"dhbecker" - It sounds to me like by now you should be motivated to roll up your sleeves and do some of this stuff yourself!

I have enough time to do engine oil changes, diesel purge, and body maintenance, and that's plenty for me. The rest I prefer to leave to a qualified MB mechanic. I really can't get excited about all the talk about orifices, etc. I did a while back though do an EGR valve (defective) removal/conversion, with advice on this forum from Brian Carlton. Fortunately, where I live emissions tests are not required, and if they are in the future, I have collector plates on the car that will never expire. With conservative driving habits, mileage has improved to 30 mpg from the previous 25 mpg (probably also helped that I specified the A/C be left off - a real money pit in my estimation) when the new engine was installed.