i am wanting to find the vacuum diagram for the transmission of my 1987 300sdl

the car seems to shift funny off and on and not in any consistent manner, a shop told me most of the time it is vacuum

are there different trans it could be , or will they all the be same number?
if they are different where on the trans would i find this?

i went to the mzf- bayer site thinking it would be on there, but they only show to the 1985 or something like that

any info to point me in the right direction would be great

thank you

On the right side of the transmission body, just above the oil pan (sheet metal "rectangle" about 2" 50 mm tall on the very bottom), you will find a string of numbers 722.3xx. That is your transmission series number. The following numbers are that transmission's individual serial number.

On the left side of the transmission, near the shift linkage, is the vacuum modulator. Check the small piece (about 3/8" 10 mm diameter, 2" 50mm long) of soft rubber tubing there that connects the rigid plastic line to the modulator. Many times this rubber is either cracked, or has stretched, preventing a proper vacuum signal.

I would suggest that your solution is the correct one: solve the vacuum problems before making random guessing adjustments to the modulator, vacuum-control valve, or bowden cable.

__________________
James Marriott
2003 Buick Regal
1983 300D (228k, frau Auto)
1996 Suburban K2500 (192k, 6.5 turbo diesel/4WD towmaster 10,000)
www.engineeringworks.biz
1987 300SDL junker 170k
1982 300SD junker, 265k

thank you very much, going to try and find those numbers now

Your SDL should have a 722.321 transmission but I think you missed the point of the advice you received. There is no vacuum system in the transmission; rather, the engine vacuum system sends a signal to the transmission. More vacuum = soft shift, less vacuum = firm shift. For a consistent shift feel, you want more vacuum at low engine speeds and less vacuum at high engine speeds.

The 86-87 SDL has a more complicated transmission vacuum signal system than other MBs of the era. Instead of only a vacuum control valve attached to the IP, there's a vacuum amplifier that considers as well coolant temperature and intake manifold pressure. The vacuum amplifier is often called the blue fyling saucer (BFS) in the forum archives. The 87 300D and TD and maybe some of the 190Ds have the same system. Other MB Diesels are content with just the VCV.

The first link in this post has the vacuum diagram you need - Vacuum Diagrams

Sixto
87 300D

thank you guys so much for all this info!

sixto i went to the link you sent for vacuum diagrams, printed that one out, my question is it does not seem like enough vacuum lines for everything in the car, since everything is vacuum controlled in it????
is there anywhere that shows every single line all the way to the end, all the way to each thing for the climate control, door locks etc?

my boyfriend is out of work right now, he is a big truck diesel mechanic so obviously can do a lot of the stuff on this car once we learn about it

this is my thought on this car and the fact that everything is controlled by vacuum that in an almost 30 year old car we should go through and replace every single vacuum line and fitting in it, which will hopefully eliminate a couple of issues we have and prevent others

then we know it has been done and are starting fresh

i realize this will probably be a big job but he can take 3 solid days if he needs to, whatever

i see that diesel giant sells some kits with the connectors in them, they seemed kind of pricey but maybe the connectors are expensive?
or would it be possible to just buy a bunch of connectors at napa or somewhere?
and also i was just going to buy a lot of vacuum hose, which sizes, etc would i need to get to do this project?

any other suggestions for doing an overall of the vacuum line system would be great

thank you for your time

I would call Phil(top of the main screen"buy parts") Great guy and he will be able to get you all the parts and info you need. Seeing no one else has said it yet AVOID THE DEALER. Same parts twice as much.

More info needed though. How long have you had the car? Miles? what have you done so far in the way of maint?

Best of luck, when the bugs are worked out these are great cars. Especially the SDL best I might be a little biased!

__________________
86 300SDL. 250,xxx on #14 Head. One eye always on temp gauge.. Cruising towards 300K

You might be thinking of the W100 which has hydraulic power windows and seat adjusters

Vacuum from the engine goes as far as the ACC system under the dash (line c in the vacuum diagram). The FSM section on ACC has that vacuum diagram but things are well protected under the dash. The parts that wear are the diaphragms in the vacuum actuators (or pods). You can get replacement diaphragms for the pods. The recirculation and defroster pods have two diaphragms each since they can maintain 3 positions. Those don't take well to replacement diaphragms. If the car is a keeper, get new pods to replace leaky pods. IIRC you can get to all the pods in a 126 without removing the dash. The center vent pod arm is riveted and I never solved the puzzle of how to remove it so I replaced the diaphragm in place (man, that was years ago). Get a Mityvac and test each pod.

There is a separate electric pump beside the spare tire in the trunk for central locking and optional orthopedic seats. I've yet to experience a central locking pod failure in a 126. I've heard of pump and lock switch failures. If central locking works (4 doors, trunk and fuel filler flap), there's nothing more to do.

Some folks replace the vacuum tubing under the hood with rubber or silicone vacuum line. That eliminates a lot of the fittings which tend to wear out the quickest. The hard vacuum line gets brittle but usually holds up until you touch it. The big case in point is the weekly thread stating, "I changed the oil and now the engine won't turn off with the key." Vacuum line only available in bulk in translucent white. You really have to twist the arm of the parts counter person to get replacement line with factory colored stripes and you'll pay for it. There aren't so many lines that color identification is imperative. Auto parts stores probably sell the vacuum line since they're used in VWs. You can use auto parts store fittings and bends as well but it might be hard to find the very tight bends. Get creative. Don't forget to keep the filters, check valves and dampers as they came from Sindelfingen.

Sixto
87 300D

it is a 1987, just had it a week or so, i finally found the shop that has worked on it for the past 7 years at least, the car has 293,000 and i am not driving it at all becuase they shop said they have not changed the timing chain, so first we are doing timing chain
they printed out all the records on the car for me , it has had a new vacuum pump- i think it is called- in the past 30,000
mostly it seemed like little stuff, links breaking, plastic pieces replaced, etc
they previous owner had it in the shop every 5000 for oil change etc and it seems if something was breaking, broken the shop would fix it
but as far as preventative stuff etc

it has some leaks on the bottom of the engine , not sure what yet
we have not had time to look it over good at all, have had 2 other major car projects that are just now getting finished
we should be pretty focused on the mercedes starting tomorrow so i will have more info

car runs pretty good overall, saw on the records it had 4 new shocks not long ago

brakes are going to need doing soon and records show previous owner ran pads down too low and it will need rotors and calipers rebuilt this next time, seems to brake great right now, but i plan to do all that when those need doing

climate control fan off button does not seem to work right, so vacumm leak there
trans is not shifting right all the time, acts weird to me, cannot describe it but since it is intermittent, etc prob vacuum and could be coming from the climate control leak
hence my reasoning for wanting to replace all vacuum lines and fittings in the entire car

will do a diesel purge and also the alda cleaning thing

after that will consider injectors

overall this car seems much cheaper than buying parts etc for my ford 7.3 diesel and i tend to keep my cars up in very good shape and go with the preventative stuff and stay ahead of issues

so i plan to get the timing chain done first, then replace all the vacuum stuff, also do the flex disc if it looks at all like it needs it

then onto checking all suspension, steering, rubber mounts all in the suspension etc and replace all that as needed


it is a nice car and i think with a little more upkeep and some new parts will be a very nice car

This is my opinion which isn't shared by everyone but I let the chain tell me when it has to be replaced. The big hint is how far from TDC the crank sprocket is when the cam sprocket is at TDC. More than 4* off at the crank means it's time for a new chain. The other hint is chain guide wear. Unfortunately much of the front of the engine has to come off to replace the chain guides. If the engine had regular oil changes with good quality oil I'd be surprised if the chain needs attention. This 606 with 277K miles has but 1* of chain stretch - E300D timing chain stretch

603 oil leaks - check the front crank seal, vacuum pump main gasket and vacuum pump brass cover fitment, belt tensioner arm attachment to the engine front cover, cylinder head near the #1 exhaust runner, IP where it meets the block, rear main seal, turbo oil supply and drain. This isn't common but my belt tensioner damper gave up and spilled fluid on the front of the engine.

Speaking of belt tensioner, that's something to keep an eye on in a 603. Release belt tension and check that the tensioner arm doesn't click as it pivots and doesn't wobble. Check that the tensioner pulley spins smoothly and quietly and doesn't wobble. I'd put my money on keeping the tensioner in good order before messing with the chain.

ACC fan control is independent of vacuum. The fan is positioned vertically and the armature(?) shifts as the bearings wear so the brushes don't make good contact. And the brushes simply wear over time. Sometimes the fan will get squeaky, sometimes it'll come on at high speed but not at low speed, sometimes it'll take an upwards kick under the passenger side dash to get the fan started. You need new brushes and/or bearings or just replace the motor. It's not difficult to move the blower cage from the old motor to a replacement motor, or you can buy a motor with cage attached.

Yes, ACC vacuum leaks can cause transmission shifting problems. Find the line from the engine vacuum pump to the cabin. It goes through a yellow (or green?) check valve ahead of the brake booster. Cap the line and see if shifting improves.

Sixto
87 300D

Forgot to mention - there is a general aversion to rebuilding MB (ATE, Bendix, Girling) calipers in the field. Those who know seem to come down on those who would split caliper halves. I don't know know why.

Sixto
87 300D