I may not be understanding what flaring is or maybe i'm not explaining it well, but flaring is when the RPMs jump quickly just before or during a shift? It seems my car isn't doing it, the RPMs are staying steady but shifting into third the car seems to have to go to a higher rpm to shift, but it's steady. No sudden jump or anything.

That said, I doubt i'm getting good vacuum to the transmission.. I suspect the routing is just plain wrong, and I can't seem to find a diagram for this model and year. I plan to try and sort it out... I do plan to try and cap off some of the other lines and what not as well.

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1981 Mercedes 240D - Automatic transmission

Please remember the tranny upshifts smoothly with zero vacuum. It only uses vac for the downshift. When your foot hits the accelerator, the VCV is designed to drop the vac quickly to zero so you get a smooth upshift.

Downshift, not so.

You can drive around town with the line to the modulator unhooked and get smooth upshifts but when you come to a stop, it will clunk on downshift. I know from personal experience.

Not sure but the Bowden cable may be what determines your shift points. Search the forum but it may need adjustment. Not sure.

The model transmission I have doesn't have a bowden cable though? And the downshift is perfectly fine, it's smooth with no clunking sounds or anything.

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1981 Mercedes 240D - Automatic transmission

Sounds like your vac in regards to the tranny is OK. The vac modulator is just to soften or crisp up the shift and if you are OK with the shifts, you might move on to door locks.

OK, I took a look at the vac lines in the SD. It is so simple that I am surprised someone else did not provide the info already. Assuming my powers of description are adequate, it goes like this (I start with the VCV as a beginning point):

1. from the bottom of the VCV is your first Y. One leg goes to the vac reservoir which is behind my left wheel well. Stick a golf tee in the other leg - it goes to the EGR.

2. from the top of the VCV is your second Y. One leg goes to the tranny. The other leg leads to your third Y. One leg of Y #3 goes to the brake booster. Put a golf tee in the other leg of Y #3; it goes to the EGR.

Simple. Now you can really check for vac leaks.

Again your 240D may be different.

Thank you! That sounds similar to what I have now, i'll have to take and look Friday. Today was spent at the DMV getting her registered! Happy to be able to legally drive her.

I'm happy to report that the shifting issue is almost completely gone, I believe the remaining issue is due to the vacuum leaks as it is fairly intermittent and I do need to replace some Y junctions... Well one Y junction I know of, but I may be able to eliminate it all together... Your setup sounds very similar to mine so i'll take a look when I can and let you know if that setup will work.

The remaining issue I refer to is the fact the car will now, very very rarely, not shift into 3rd gear like it did before. However, the majority of the time I would say it shifts just fine! In fact the issue is so uncommon now that it happened once in my hour of stop and go traffic. (Have to love Las Vegas, and of course school zones in the morning)

Per my fiancees insistence I'll be getting a oil change likely this week or next week as well, and I'm going to try and clean the underside of the car as well. My boss is willing to give me some ramps he got for essentially free (turns out pep boys will give you $400 worth of gift cards if you spend over 3k building a engine...)

Also on the note of door locks, I do not see a button for the locks they seem to be all manual. Is that how it should be, or should there be a button somewhere? The vacuum lines for the locks I know are currently disconnected, due to the bad Y junction. Should all the locks just lock and unlock with the driver door?

I also have to take out the lock cylinders (the driver door cylinder literally pulled out when I tried to lock the door! It seems the retaining loop snapped...) so i'm going to swap the driver and passenger lock cylinders.. They both also seem to be seized or perhaps I have a incorrect key...

I'll be ordering a spare key as I seem to have trouble finding a place to cut a spare mercedes key. Likely be ordering it online. Also is there any way I can get a spare door lock cylinder keyed to the car VIN? Or is that not possible?

Thanks for all the help guys!

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1981 Mercedes 240D - Automatic transmission

Take your VIN and a copy of your title to the dealer and they can make you another key. I suspect a locksmith could do it too.

I assume a 240D has vac door locks but maybe not.

Thanks for the tip! I seen in another thread there's a classic mercedes place in fresno I think it was that does it too...

Yes it seems my car has the lines for vacuum locks, that said the vacuum lines are disconnected and I am honestly not even sure they hold vacuum... My question is, how do the vacuum locks work?

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1981 Mercedes 240D - Automatic transmission

There is a vacuum actuator in each door. In the SD they are connected by vac lines to a multi-connector under the carpet at the front of the front passenger seat. Your vac goes from the engine compartment to the multi-connector there and is split to each door, the trunk, and gas cap door. Pull the carpet up. Then put a mityvac on one line at a time. If it does not hold vac, that door actuator is bad. (Different in an SD where there is a separate pump in the trunk for the doors, trunk, and gas cap door but I believe your 240D runs from the front pump.)

A few years ago they were about $25 each. Just remove the door card and replace the actuator. It is unlikely that all four door actuators are bad.

I just looked at the pics in your first post and note the vac lines are somewhat different than my SD. For one thing I think you have a vac line going through the firewall to handle the door locks - SD door locks operate on a separate pump located in the trunk. The "soon to be deleted" EGR gizmos on the valve cover are significantly different (and simpler) than mine.

So someone who has a 240D please speak up and help us out here with the vac lines. I could unwittingly be leading you astray.

Saw this in a recent post from H3ffe. Might be helpful.

Call the classic center in Irvine and order one. You just have to email a scan of your DL and title. Took two days for w123 and about a week for w124. Cheaper than the dealer.

I was referring to the vacuum valves on top of the rockerbox as shown in post #9 ~ nothing to to with overboost, only affects tranny shifting and EGR valve.

The EGR valve often fails partially open, why it's so important to TEST IT FIRST

.

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Nate - you have a 240D and I do not so I am just guessing.

Can you help him out with the proper routing for the vac hoses? I tried but the 300SD is obviously routed a bit differently.

I'll give it a go, once he's done the basics already mentioned and reports what happens .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Thanks! I'll have to do the testing likely Saturday, I have a 16 hour shift starting at 3 this afternoon so I'll be dead asleep most of tomorrow..

I'll give everyone a update on Saturday or Sunday!

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1981 Mercedes 240D - Automatic transmission