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1985 380 SL
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Discussion Starter · #1 · (Edited)
Hi,
I have an automatic '83 240d that suffers from late, hard shifting. I've replaced all of the rubber connectors and the yellow and green valves on the vacuum lines-which helped. But its still shifting too hard and too late.

I've read that blocking the EGR and simplifying the vacuum lines can help quite a bit. Could someone tell me exactly what lines to block off or how to go about this on a 240d?

People seem to have success removing all the lines to the black box on the valve cover. But Im not sure if that applies to a 240d.

Any help would be really appreciated!! Ive attached the vacuum diagram. Any photos/diagrams of what to do would be REALLY helpful!

Thanks!
 

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2001 Volvo V40
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Late and hard shifting indicates a vacuum leak.

If the switchover valves on the top of your valve cover are leaking, simply switching off or blocking the EGR line will not produce results. Other possibilities are a malfunctioning Vacuum Control Valve or a leaking vacuum modulator. Leaking vacuum lines in other vacuum systems, such as the central locking, can also produce late and hard shifting.

The reason why blocking the EGR works on some models is that the switchover valves on the valve cover only control the EGR. Possible leaking in the switchover valves is thus eliminated. As GarrettTA031 has mentioned, on the 240D the switchover valve is also used to downshift to 1 at take-off and to keep in 2 at stops, so removing the switchover valve is not advisable.

The only way to check the system is with a vacuum pump and a vacuum gauge, so that you can determine which component is leaking or not.
 

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1985 380 SL
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Discussion Starter · #4 ·
Thanks -thats really helpful info! I'll start by just plugging the line to the egr. Should I cap the nipple on the egr too?

Ive never inspected under that black cover. The car spent years in AZ, so Im sure any rubber is going to look pretty tired and cracked.

I don't have a pump or gauge-so I'll have to buy a set.

123 Chassis Deluxe Vacuum System Troubleshooting Kit | MercedesSource.com
Does anyone have any experience with this kit? It comes with two manuals. I've never done vacuum testing before, so Im thinking it would be helpful. The plastic brake bleeders seem to be about $40, this one is brass.

I have PLENTY of issues with the central locking. I didn't realize that could affect shifting too!

The central locking doesn't work at all when I turn the key in the door. Once I start driving-all of the doors unlock themselves.

If I try to unlock the passenger side door with a key, it tries to immediately lock itself before I can open the door.

Any thoughts on where to begin? :confused:

Thanks for the replies!
 

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2001 Volvo V40
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The Switchover Valve system isn't made of rubber, more hard plastic, but it can still leak. Open the cap and see if something is worn out.

Easy/cheap things to do without a pump:

- try blocking off the central locking system and see if that improves shifting

- replace all the rubber socks, three-way and four-way pieces which connect the vacuum lines to the various components.

- replace the rubber O ring under the cap of the vacuum modulator.


Repairing the central locking usually involves changing all the rubber components.
 

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1985 380 SL
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Discussion Starter · #6 · (Edited)
Thanks very much for those suggestions- I really appreciate it!

I took off the black plastic cover and discovered a line that was capped- with a badly damage cap that was obviously leaking. Not sure if thats the cause of my problems..but Im sure it didn't help!

I'll follow your suggestions for the locking system, that certainly makes a lot of sense.

I've replaced all the rubber socks recently- but I'll check again to make sure I didn't miss one.

The O ring could most definitely have dried out- the car was exposed to very hot/dry temps for part of its life. I've also read that the cap on the modulator can crack and leak. I'll have to check that too.

thanks a ton!
 

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1967 250 SL, 1965 300SE lang
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Repairing the central locking usually involves changing all the rubber components.
Repairing the central locking on my 85 300TD involved replacing the leaking actuators in one of the doors and in the rear panel door.
 

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1985 380 SL
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Discussion Starter · #8 ·
Really appreciate the input. Im starting to get more of an idea how this setup works -thanks to all the help here!

I replaced the damaged hose cap that was under the black plastic cover. HUGE improvement!! The car drives much more smoothly already.

Tomorrow Im going to try blocking off the locking system and the egr to see if that improves things even more.

I noticed the vacuum line that goes to the egr first goes to a small black box. Should I plug the egr line before or after this black box? Is this the egr selenoid Garrett is referring to?


Thanks again for any help!
 

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1967 250 SL, 1965 300SE lang
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123 Chassis Deluxe Vacuum System Troubleshooting Kit | MercedesSource.com
Does anyone have any experience with this kit? It comes with two manuals. I've never done vacuum testing before, so Im thinking it would be helpful. The plastic brake bleeders seem to be about $40, this one is brass.
I recommend against that kit. Instead I would buy a Mitivac and read this article:
Mercedes Vacuum Troubleshooting

I would also look at a map of the vacuum lines for the car - the lines are under the carpets and covered by plastic covers. You need to get to the line junctions to test the individual components to make sure they hold vacuum in both the locked and unlocked circuits, and you do NOT need to remove door panels to do that. When you find vacuum components that leak, then you remove the door panels and replace just those. I would get parts form autohausaz because they are cheaper. I would not by the "fix it all kit" because most of that you don't need, and other parts you will need. But you absolutely need a Mitivac or other good vacuum gauge.

I have PLENTY of issues with the central locking. I didn't realize that could affect shifting too!
Depending on year and transmission, a vacuum leak will cause hard or soft shifting.

The central locking doesn't work at all when I turn the key in the door. Once I start driving-all of the doors unlock themselves.
The central looking DOES work, it is just that the vacuum storage is all leaked out when you are trying. Got two keys? Start your car and get out. (running car will build up some vacuum -- if you had a really bad vacuum leak you wouldn't have enough vacuum to shut the engine off). Leave car running and get out and close door. Try the key in the door lock. Does it lock everything? Does it unlock everything? There's a good chance it does, but that doesn't tell you where the leak is. Does it lock/unlock everything but one door? That's a good suspect then.

If I try to unlock the passenger side door with a key, it tries to immediately lock itself before I can open the door.
This is because a) the car thinks the doors are locked and b) the rod with a spring clip inside the door has failed. Take off the door panel and you will find a metal rod going from the door lock button down to the locking mechanism. There is a spring mechanism in this rod that allows you to spring the lock open even if the actuators have the door locked. When the spring mechanism fails, you get this result. The fix is to replace the rod. It's a cheap junkyard part and probably not that expensive new. What you are feeling is the pressure from the vacuum actuator trying to keep the door locked against the pressure of you turning the key. You should never feel this since the rod with the spring should just "spring" and let you unlock the car. The result should be that the car's vacuum locks are all in the locked position and the passenger door overrides that with the spring rod, but the passenger door actuator is still in the lock position. When you later unlock the car with the car's vacuum locks (controlled only by driver's door lock) then the spring rod mechanism on the passenger door will "spring" back into the normal position. Difficult to explain, but very easy to understand if you play with a spring rod that functions.

Scott
 

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Discussion Starter · #11 ·
Thanks for the advice!

I went ahead and ordered a mityvac. That link is REALLY helpful!

I tried the locks with the engine running. The key still only controls the drivers side door. Nothing happens to the gas flap or trunk either.

Like I mentioned, as soon as I turn on the car- all of the locks unlock- and pop right back up if you try to lock them.

I also tried blocking off the egr and the locks- both seperately and together. It all made the shifting much worse.

Hopefully when the mityvac arrives I can pinpoint the issues with the locks and that will smooth things out.

Could someone tell me the correct shifting points for a 240d? I haven't been able to find the exact numbers, so Im not exactly sure what I am shooting for.

Thanks a ton for explaining the door spring! Im going to drop by the pick and pull this weekend and see what I can find.

really appreciate it!!
 

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2001 Volvo V40
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Below are the shift points for a 240D with a 722.1 transmission.

The speeds are in km/h, so you'll have to convert them to mph or look at the km/h scale on your speedometer. The speeds are approximate.

It is from the German Factory Service Manual. Leergas means very little load/only pressing the accelerator pedal very lightly. Vollgas is full load, Übergas is kickdown.

 

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1967 250 SL, 1965 300SE lang
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Like I mentioned, as soon as I turn on the car- all of the locks unlock- and pop right back up if you try to lock them.
That means that your spring rod gizmos are wonky on all of the doors except the driver's door, which doesn't have that thing. The actual piece is different for each door, and I think I recall there being an early version and a late version. Check EPC or take a good look at your existing part. You probably can't see the actual spring part of the rod while it is in your door - I think the spring part is behind the inside door skin but again, I don't remember. Some of the ones at the junkyard will already be broken.

Scott
 
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