Hi folks. I am brand new to the forum and I am impressed!
Sam, looks you "da-man". Rather than go through 40 pages of posts my question hopefully is quick. I by-passed the EGR and took care of the harsh 1-2 shift. Vac. at idle is 12"Hg. 0" Hg at full throttle. Some flaring at 2-3 with vacuum in the 4-5" Hg range. What is/are the target vacuum ranges for the intermediate shifts.
Heading down to the MB dealership for the orifices now.
Again, thanks for this great thread!

Please tell us what kind of a car you have.

And special thanks goes out to...
 

Yes, I read all 40 pages of information (and misinformation.)

The upshot is that with your help, Sam, Brian, Dan, I now have in my 300SD 83Fed, a tranny with 272K shifting quite nicely.:D

I adjusted the vac at the VCV (9.5"Hg), replaced the rubber modulator cap/cover and most of the t's and orifices, connecting hoses, and took up some (not all) the slack in the bowden<?SP> cable. Shifts are now (mid throttle) 1.) about 2500 2.) about 3000 3.) about 4000 4.) about 3500. Trans Switchover valves and EGR seem to be functioning nicely as well, getting about 28+ in the city.

Plenty of pull, my 0-60mph is just under 18sec.

Next job: Timing chain, front brakes...

Welcome to the forum.

If it's flaring on 2-3 with 5" vacuum, you could try to reduce vacuum at idle to 8" and see how it goes. It might cure the flare if it's not too bad.

Hi folks,
The MB I have: '83 300SD 142K Mi Chassis W126 Engine: 617.95 Tranny: 722.3.
I have performed a full system leak test -- it holds vacuum well, about 0.2" Hg loss in ten minutes. The flaring at 2-3, which is not too bad, is occurring at ~5" Hg when acceleration is gradual. If I push the acceleration such that vacuum is less than 2" Hg, no flaring. It appears I am missing the first orifice (#62 on the vacuum line schematic) -- does anybody know what orifice size this is suppose to be?
Now, if I have plugged off the EGR valve, do the 3-2 valves now have a purpose? Looking at the vacuum diagram, I should by-pass them as well and avoid a potential source of leaks. No?
FYI, according to my MB dealership, the following orifices are no longer available in North America:
Red, 1.1 mm, PN 1162761029
Brown, 0.9mm PN 1162761429
White, 0.8mm PN 1162761229
This is my first exposure to the diesel engine -- loving it!

Wot
 

Are those the shift RPM's at WOT?

floydla1 - I will respond by editing your quote below...
 

Regards,

The needle valve is a GREAT idea! While reading your post I am slapping myself -- why didn't I think of that!

Your orifice is in place and functioning properly. You can't find it because it's just a small round sliver of plastic between two rubber vacuum lines. If any dirt has accumulated, it's effectively invisible.

The first thing to do is to remove the 3-2 valves from that system. They only serve to run the EGR. Here is how to eliminate them:

http://www.peachparts.com/shopforum/1375506-post5.html

After you remove the 3-2 valves, get a reading on the vacuum levels at idle and as you drive it. It's possible the flaring will increase. If so, report back and I'll show you what to do with it.

The needle valve is an addition that is not required for your vehicle. All adjustments can be accomplished with the existing systems on the vehicle. Those adding a needle valve have a non-functional VCV and they don't want to replace it because it's costly.

Hello Brian -- reporting back.

Sorry for the response delay. Yesterday being Valentine's, I thought it best to spend quality time with my girlfriend.

So, this evening I quickly isolated the black box and plugged the tees with golf-tees (I'll clean it up later). Vacuum at idle (~700 rpm) increased slightly to 12.5" Hg. At 50-60 mph the vacuum is between 7.5" Hg and 8.0" Hg. If I gradually accelerate from a stop such that the vacuum stays 4" Hg or above, there is flaring at 2-3, but I can not say that it is any worse that before isolating the 3-2 valves. If I accelerate such that vacuum stays below 3.5" Hg, shifting is smooth through all gears. No problems downshifting on full throttle. Whatcha think?

Agreed.........I did the same.........


Good job on the tests. What you need to do is to find the small dome on the side of the VCV and carefully lift it off with a sharp knife. Beneath the dome should be a small screw secured by a locknut.

Before making any adjustments, disconnect the main vacuum supply line from the T above the VCV and connect the Mityvac to this hose. It'll be the Mityvac on one side, the transmission modulator on the opposite side and the VCV on the bull (via the damper). Pump up the mityvac and confirm the 12.5" at idle. It should hold vacuum reasonably well..........bleed down in 20 seconds or more.

With the Mityvac pumped up (you'll have to keep squeezing if it's falling), release the locknut and turn the adjusting screw about five degrees (clockwise.......IIRC........but, it's been awhile). DO NOT TURN MORE THAN FIVE DEGREES. Watch the Mityvac and look for a reduction in vacuum down from the original 12.5". Keep pumping the Mityvac during this process. If I'm wrong in the direction of the screw......turn it very slightly counter-clockwise.

The goal is to reduce the vacuum at idle to approx. 8". If you achieve this, tighten the locknut, replace the domed cover, remove the Mityvac, and reconnect the main vacuum line.

Take it for a test drive. The 2-3 flare should be gone.

Report back with result.

You're right. That is WOT, not Mid-throttle like I wrote. They're rough observations...

Aside from 1/2 (about 3000) All my reg. cruising shifts are between 2000 and 2500 or so.

Sure is behaving a lot better, though.

Hello Brian,

Reporting back. I confirmed that there was no orifice in the tee to the VCV / modulator, so I waited to make adjustments to VCV until I got the orifices from the MB dealership. I put the smallest orifice in, but the vacuum was still in the 12.5 - 13.0"Hg range at idle. The adjustment on my VCV is not a screw / locknut, but just a 9mm nut. Adjusted vacuum to 8.1" Hg at idle. 1-2 shift is firm, flaring at 2-3 is gone, 3-4 smooth. Lookin good! Thanks. Now, on to the oil cooler hoses!

Interesting...........the addition of the orifice didn't make much of a difference. Certain people are going to be shocked by that revelation..............

Based upon your original readings, I'm a bit surprised that no orifice was present...........the vacuum levels were quite normal.

Maybe there was an orifice of dirt at the T on the main vacuum line. It one time, I had very hard shifts because I had no vacuum to the tranny. Problem was total blockage of the T at the main vacuum line. Could partial blockage at this point have the same effect as an orifice?

I thought the 3/2 valve had something to do with transmission shift also? Not true? As I recall, Dieselgiant's site has a procedure to replace the 3/2 valve to restore proper shifting? Curious why it is called the 3/2 valve. I still have mine. Going to get rid of it now.

It depends on the vehicle. My comments are vehicle specific. You can remove the valves on the 300D turbo.........not on the 240.

Thanks Brian. Can you explain why?

The 300 turbos use the vacuum strictly to control the speed of the shift........not the timing of the shift. They have a Bowden cable for that purpose.

The older systems used vacuum to control the speed of the shift and to also delay the shift depending on the vacuum level. They didn't have a Bowden cable.

So, certain older vehicles........240's for sure.......cannot have those valves removed without affecting the transmission performance. I'm really not certain of the years and models that are related to this situation, but I'd presume that for any vehicle without a Bowden cable, it will certainly be applicable.

Brian I am having trouble with my 81 300SD. The problem I am having is a kinda slow shift from 2-3 under heavy throt. and worse flaring when its shifting from 3-4. It seems to shift fine though when not under heavy acceleration. This all seemed to happen overnight, as the day before it shifted great until I went through water over the roadway.

Ideas?

Cannot tell anything until you hook up a vacuum gauge to the modulator line and advise what you've got.

Read the gauge at idle and at various pedal positions while you drive it.

Nothing in 1-2, 2-3, barely move in 4
 

Brian,

Was driving on a main highway for about an hour at 70, entered the city and slowed to make a right turn. When accelerating(gently!) out of the turn, I heard/felt a clunk, a bang and it just flared like crazy. I could get it to move only if I revved to 3500-4000 rpm and then backed off a bit. It then slowly gathered speed enough to make it home(about 70 miles). Vacuum is good to the modulator, and the VCV leaks off from 12" to 5" in about 20-30 seconds. When I checked the fluid right after it happened(before returning home), it was 1/2" high on the dipstick and had some small bubbles. After returning home and letting things cool for a day, the fluid was where it should be and the color looked ok(red not brown). Also discinnected the vacuum line to the tranny and it seemed to move a little better, although still flaring badly. Ordered 2 AT filter kits yesterday and will change fluid/filter, add Trans-X, run engine for an hour or so, drain and change filter, fill with AutoZone Dexron III/mercon(only kind available locally) and hope for the best.
Question: Should I also try to get the K-1 and K-2 kits and install them at this time? If so, what are the p/n's for them. Thanks for any advice as the closest M-B dealer is in Tucson(500 mile round trip). I really hope that there is a solution other than a rebuilt tranny.

PS, haven't pulled pan yet to see if any strange pieces down there as only place to work is open to the wind and dust(it's Mexico) and when I do open it up, I will need to make some kind of wind/dust barrier.

Dave
'81 300SD
'81 VW diesel caddy

Oops....forgot
 

Car in my previous post with tranny problem is a '81 300 SD with 187k miles. Tranny is 722.303 02, s/n 073124 and is original trans(I think). Car was purchased 3 years ago with 153k miles. No idea who previous owner was as it had been a church donation for charity/fund raising sale.

Sorry 'bout that.....Dave

I believe we need to qualify "flare". When the transmission pulls properly in all gears, but disengages into a false neutral between gears, that's a "flare".

When the transmission won't pull the vehicle forward under normal revs.........and very high revs are used to move it........that's "slipping".........a completely different diagnosis.

It's important to state exactly what's happening with it and I don't believe it's a simple "flare".

If it won't easily move from a standing start in first and second gears, the problem is likely to be the B2 piston. Do some research on "B2 piston" and see if the symptoms are similar to what you've got.

Slipping it is
 

Brian,

Thanks for your quick reply and clarification between "slipping" and "flare" as I thought they were the same. Anything else that you think I should check/replace, ie. K1-K2 kits? Do any of you out there on this thread have a p/n for the B2 piston parts(kit?)? I'll check back in after fluid/filter change and tell how that went. Will be going to the US sometime soon and will check M-B dealer for the parts unless you guys think ordering from Fastlane would be better and less expensive. Again thanks!

Dave

B-2 in pieces
 

Brian,
B-2 piston came out in pieces. Rubber seal over bushing torn getting out, however the bushing(aluminum) is stuck and looks to be out of round. Is it a wise idea to try(very carefully) to cut it out using a very sharp knife, like a box knife? I don't want to take any chance of scoring the piston cylinder, but the bushing housing will have the new bushing covering any incidental scratches( hopefully Very few). Do you see any problems doing it this way and if so, any suggestions for getting that bushing out w/o damage? I have had no success trying to find a tool to remove that bushing locally. Again, thank you for all the help that you give us folks out here in the hinterland. I've learned more from your posts(and those of other members) than I ever have from just reading manuals. This forum is a treasure!
Dave

I've checked the sources in beginning part of the thread for a vacuum diagram. My car is a 1989 190D 2.5l automatic they don't list it. Anyone know where to get the diagram.

I change my oil and fuel filter and checked the air filter now I'm having shifting problems. Probably knocked or broke a vacuum line some where.

The transmission won't shift into high gear revs to 4500+ rpm


Thank You

Find the kickdown switch beneath the accelerator pedal. Unlug the switch. Take the vehicle for a drive and see if it's cured.

WOW that was quick.

It was unplugged and I plugged back thinking it was the problem. It did get a little worse about revving. I'll unplug it but the shifting problem existed before I plugged it back in.

It would suddenly down shift for no apparent reason after car warmed up. Then it would not shift into high gear unless it revved then took foot off accelerator. Shifted into high for a less than a minute and down shift again

Your original problem was that it wouldn't upshift.

Now, it will suddenly downshift.

Maybe you better provide all the symptoms in a single post??

I change my oil and fuel filter and checked the air filter now I'm having shifting problems. Probably knocked or broke a vacuum line some where.

The original problem was It would suddenly down shift for no apparent reason after car warmed up. After it would not shift into high gear unless it revved then took foot off accelerator. Shifted into high for a less than a minute and down shift again.

Trying to find problem I found the down shift switch unplugged. I plugged it in and now it would not shift with out real high revving.


[B]Vacuum pump went bad . replaced pump Solved all issues Thanks[/B]

You might have more than one problem. The switch is definitely NG. Leave unplugged until you replace it.

The downshift, and late upshifts are caused by a Bowden cable that is too tight. There's an adjustment to slacken that cable which will bring earlier upshifts and delay the downshifts. I'm not sure of where the adjustment is on that vehicle. Maybe others can help you with that location.

Also, if you wish to continue with this discussion, it should be done on a new thread.....this one is for vacuum issues.........not your problem.

No problems before I did the service work I did.

I think I either disconnected or broke a vacuum line unknowingly. I struggled to get the air filter box out.

Looking for vacuum diagram

Maybe you accidently disconnected the end of the Bowden cable that links to the accelerator assembly? On a 123, it's a ball and socket type fitting.

My car (82 300sd) won't shift into 3rd or 4th. Changed trans. fluid and was burnt smell. Any ideas?

'82 240D Shifting Issues
 

Out of the blue, the trans stopped shifting correctly. Shifted only at near-redline. Thought it was the modulator. Not so. No vacuum to modulator. Read the post on bypassing the 3/2 valves. Tried that and shifted to first at 40k and wouldn't shift past that. Have the line to the modulator plugged into the main vacuum and the car shifts through 4th with flaring. Can put it in low, give it gas and it'll shift, near-redline, through 1 and 2 simultaneously then can manually shift into 3 and then 4. Have used the peterschmid diagrams to try to isolate the issue. Am thinking the 3/2 valves need replacing. Or, how do you bypass them in a 240d? Tried the fix for the 84 300d but it's a different scheme. Have fun, Jonathan

Welcome to the forum.

Go down beneath the accelerator pedal and find an electric pushbutton switch. Find the plug to the switch and unplug it. Drive the vehicle again and report back with results.

Unplugged Switch
 

Hello Brian:

Unplugged the switch. No change. Tried it with vacuum straight from the main and also as per the schematic.

As per the schematic, the car shifts from 1-2 harshly at 40k and will not shift beyond that. Straight from the main it shifts 1-2 ok, 2-3 flare, 3-4 flare all before 45k/h.

Does it matter which connection on the main is used? There is one on the one way valve and one just after. Have tried both with exact same results.

Have fun,

Jonathan

Can you elaborate on this statement, please?

With full vacuum to the modulator, at what speeds do the shift points occur with very light throttle? I'm not interested in the flare at this point in the discussion.

Shift Points
 

1-2 less than 20k (speedo starts at 20) -- I'm guessing 12-14k
2-3 at 27k
3-4 at 43k

JM

What does "27k" represent?

I need the shift points in rpm for the 1-2, 2-3, and 3-4 shifts at very light throttle with full vacuum applied to the modulator.

speedo only, no tach
 

27k is 27 kilometers/hour. My 240d has a speedo only. No tachometer.

From the data presented, I conclude that the engine shifts at reasonably proper rpm's provided that the modulator has full vacuum.

To be positive, please disconnect the vacuum from the modulator completely and run the same test again and note the vehicle speeds of the shifts.

If they increased significantly (3X or so), the problem is a simple vacuum leak. This could occur at the 3-2 switches or anywhere else in the system. You'll need a Mityvac to track it down.

No vacuum test....
 

Unplugged the line to the modulator and plugged the T.

Trans shifted 1-2 at 35k/h and would not shift past that. Very strange. When I had the new modulator installed, it only shifted at redline all the way through the gears. The trans guy figured out there was no vacuum to the modulator and routed the line to the modulator directly to the main vacuum line. Once it had direct vacuum he kept "tightening" the modulator trying to adjust the shift . Why won't the trans shift past 1 without any vacuum, now? Has the modulator been adjusted too far?

JM

So, you've confirmed that you have a vacuum leak somewhere in the system and the modulator is not receiving proper vacuum levels to keep the shifts down at reasonable rpm levels.

Must track down the leak with a Mityvac............

On a mission....
 

Thank you, Brian. Will isolate leaks this evening. Should I plug the switch under the accelerator back in? What is it called and what does it do? JM

Yes, you can plug it back in. It's a switch to delay the shifts until redline of the engine...........when the driver has mashed the pedal and must have all available power. It's the usual culprit in these scenarios...........but, not yours..........unfortunately.

'82 300SD has no forward gears; reverse only!!
 

Hi all!!

Well, thanks to my friend jhooligan, I'm here and glad of it!!
I have my own collection of bikes (BMWs) and cars (many, including an '83 300SD and an '84 300D), but I'm asking this now on behalf of another friend. Dmitri has an '82 300SD that was working perfectly until it suddenly lost all forward motion. He drove home from across town in reverse! Thankfully it was late at night.

Anyway, Jonathan (jhooligan) informed me that the transmissions rarely fail, and often their problems are caused by external control systems. Is there a possibility that Dmitri's transmission might still be ok?? The fluid is full and still looks fine.

Thanks in advance!

Dave

Well, Jonathan is incorrect with his diagnosis. This transmission did fail and it failed most likely due to a B2 piston fracture.

Here is how to fix it.