i just bought a 240d and the trans is actin up

[gezpacho]

i have just bouht an '82 240d and the transmission won't shift unless i floor it. then it shifts quite hard. this is mainly on second gear and less in the progressing gear shifts. when it downshifts there is nothing wrong. the man i bought it from said that i needed a new vaccum modulator. is there anything else that might be causing this problem and is it fairly common for a car this age or does it indicate someworse problems? the shift points are as follows 1st 30mph, 2nd 40mph, 3rd 55mph, od high 60's. any help is appreciated as i am completely new to both diesels and mercedes.

thanks everyone
juan.

[mbdoc]

that trans requires vacuum for shifts, check for loss of vacuum!
There are vacuum controls on the valve cover & on the injection pump.

[gezpacho]

yeah the guy i bought it from mentioned that.... he said to check for a loss of vaccum or replace the vac lines. i don't know where i could get those thought. also it would not shut off when i took out the key when i first started and stopped it today. it eventually stopped but it was kinda a rough stop. the problem corrected itself later which leads me to believe that i have a poor vaccum. might also be the reason the locks act funky too.... those germans were crazy about vaccumes weren't they? more importantly, how would i go about adressing and fixing a poor vaccum?


thank you very much for your help.

Originally Posted by gezpacho

yeah the guy i bought it from mentioned that.... he said to check for a loss of vaccum or replace the vac lines. i don't know where i could get those thought. also it would not shut off when i took out the key when i first started and stopped it today. it eventually stopped but it was kinda a rough stop. the problem corrected itself later which leads me to believe that i have a poor vaccum. might also be the reason the locks act funky too.... those germans were crazy about vaccumes weren't they? more importantly, how would i go about adressing and fixing a poor vaccum?

All these issues are related to vacuum. As a starting point, this is a general vacuum diagram for your car:

http://www.ultrahot.com/vacuum/fuel_egr_240d_auto.jpg

http://www.ultrahot.com/vacuum/interlock_system_layout_1_0203.jpg

If you look at the engine, you will see a large vacuum line that rums from a vacuum pump on the front of the engine to the brake booster. There are a number of smaller vacuum lines that branch of the main line to the tranny controls, the door locks, and the fuel shut-off (though the ignition switch). A leak anyplace in the system will cause a lack of vacuum that will effect everything. If you search this forum on "vacuum", you will find lots of detailed discussion on how to track down leaks. In general, if can narrow down the leak by plugging one branch line at a time until the symptoms go away. When you find out what part of the system has a leak, you can keep chasing it by isolating branch components and looking for obvious leaks. It's not difficult, just tedious.

[mbz240d1981]

It has to be a bad leak or a pump failure to have this kind of an impact. Very rarely will you find it in a single line. There are too many check valves in too many different places to allow one single line to shut your car down like this.

I would say that you have a ripped diaphram in your vacuum pump. Or you have some valves plugged in your pump.

The other perdiciment would be that you have a modulator out at the transmission and a massive leak in your door locks. The modulator would make the car have shifting problems and the major leak probrably coming from the right rear door, trunk or fuel door is causing the shut off and door lock problems.

A simple trick I learned is to, look for the door lock vacuum lines above the brake booster on the driverside firewall. Plug them with golf tees and see if the car shuts off and or shifts better. Then just start eliminating possible problems if symptoms don't change.

Bottom line..... I would suggest pulling the vacuum pump off and putting a rebuild kit in anyway. Next replace the $35 ? somewhere around there modulator, make sure its the right color, and don't use a used one, the one you have is used!

Hope this helps, I have had many many Mercedes with these problems and although their symptoms are always simlair there solutions vary substantially.

Good Luck and happy learning!

Ryan

[gezpacho]

how difficult is a rebuild of the vaccum pump? also how expensive? i will replace the modulator, but the doors might have leaks? do i have to remove the panelling on my doors? is there a line that i could just plug to get rid of the vaccume to the locks totally or will they just not function at all then. the vaccum pump is situated on the front of the engine right? could you explain what it looks like and the best way to get it out? sorry for all the qusetions that you've probably heard a millilon times before but i'm sooooo nooob. thank you once again.

Originally Posted by gezpacho

how difficult is a rebuild of the vaccum pump? also how expensive? i will replace the modulator, but the doors might have leaks? do i have to remove the panelling on my doors? is there a line that i could just plug to get rid of the vaccume to the locks totally or will they just not function at all then. the vaccum pump is situated on the front of the engine right? could you explain what it looks like and the best way to get it out? sorry for all the qusetions that you've probably heard a millilon times before but i'm sooooo nooob. thank you once again.

IMHO, you want to do a little troubleshooting before you start replacing things. The vacuum pump is located on the front of the engine, left side. There is a large vacuum line from the pump to the brake booster on the fire wall. The other (small) vacuum lines branch off this main line.

First, do the power brakes seem to be working correctly? If so, the vacuum pump is probably OK. If the vacuum pump seems to be working, find the small branch connections from the large vacuum line. One of those lines goes to the engine components, the other splits into several lines and goes through the fire wall. Try plugging the branch connection that goes through the fire wall (to the door locks and the fuel shutoff valve). Try driving the car and see if the tranny shifts normally. Let us know what you find.

[gezpacho]

yeah i tried plugging that branch that goes throught the firewall towards the passenger compartment. the one that is supposed to be for the locks, i hope. it drove a little differently but mostly the engine would not stop at all. before when i turned it on and then immediately shut the engine down it would wait about 15sec and then sputter out.when that branch was plugged it ran just finewithout the key in it and did not shut down until i manually hit the engine shutoff on the engine..... i didn't really get to drive it for very far or long but i didn't feel it shift either. i drive it a bit more and let you guys know if anything is different. hmmmm this is tedious. also there is a red switch on the center console just behind the shifter that does not do anything but apear to turn off my turning signals. i think it is supposed to be my hazards but i am not sure. anyone know for sure what exactly it is? i know that it is going to take a while to get this car tip topish and thank you for the help.

Originally Posted by gezpacho

yeah i tried plugging that branch that goes throught the firewall towards the passenger compartment. the one that is supposed to be for the locks, i hope. it drove a little differently but mostly the engine would not stop at all. before when i turned it on and then immediately shut the engine down it would wait about 15sec and then sputter out.when that branch was plugged it ran just finewithout the key in it and did not shut down until i manually hit the engine shutoff on the engine.....

It's normal that the car did not shut-off because the line you blocked controls the engine shut-off as well as the door locks. The point of blocking it was just to see if your tranny problem would go away.

Originally Posted by gezpacho

i didn't really get to drive it for very far or long but i didn't feel it shift either. i drive it a bit more and let you guys know if anything is different. hmmmm this is tedious.

If the car still wasn't shifting with the line to the firewall blocked, you may have a leak some place in the line that goes to the engine, or you may have a problem with the vacuum pump, or the brake booster. This is tedious, but it's just a matter of tracking down the problem. Do your power brakes seem to be working normally? Do you have a vacuum gauge that you can connect to one of the branch connections at a time to try to identify the location of the leak, or leaks? If you block the branch connection to the engine, and connect the line through the firewall, does the car shut off normally, or does it still take 15 seconds? Have you taken a good look at the vacuum lines and connections in the engine compartment for any loose connections or cracks?

Originally Posted by gezpacho

also there is a red switch on the center console just behind the shifter that does not do anything but apear to turn off my turning signals. i think it is supposed to be my hazards but i am not sure. anyone know for sure what exactly it is? i know that it is going to take a while to get this car tip topish and thank you for the help.

The red switch is for your hazards, and it can affect your turn signals. If your turn signals are working, it's likely the switch is your problem.

[gezpacho]

yes my brakes work just fine, powered? i don't have to stomp on them. i reattached the hose and it shut off. it seemed to shift better for a while after i unplugged the hose and replugged it, anyone seen that before? i do not have a vaccum gauge handy. would it be possible or wise to disconnect all the lock lines and leave the ignition line intact? tomorrow i have most of the day free so i am going to do a more in depth trouble shoot than today. the hoses i should be most concerned with are all of the hoses on the top of the engine right? is my fuel door supposed to pop open? i searched for a botton for quite a while gave up and just opened it by prying it open with my key. just curious but is that little turning thing on my dash under the left hand side of the gauges a windup for the dash clock?
thanks for answering all my questions.

Originally Posted by gezpacho

yes my brakes work just fine, powered? i don't have to stomp on them. i reattached the hose and it shut off. it seemed to shift better for a while after i unplugged the hose and replugged it, anyone seen that before?

Your power brakes use vacuum, if they are working correctly your vacuum pump is probably OK. If messing with the vacuum lines improved the shifting, it sounds like you have a vacuum leak, or leaks, causing your problems. I suspect everyone that has ever owned a 240D has had this problem, including me. It's just a matter of chasing down the leaks, or paying someone else to do it.

Originally Posted by gezpacho

i do not have a vaccum gauge handy. would it be possible or wise to disconnect all the lock lines and leave the ignition line intact? tomorrow i have most of the day free so i am going to do a more in depth trouble shoot than today. the hoses i should be most concerned with are all of the hoses on the top of the engine right?

You can disable the vacuum lines to the door locks by plugging just those lines and keeping the ignition line operating. I believe the ignition line is brown on your car, just try one at a time and see what happens. If you disable the door looks, most of the remaining lines are in the engine compartment.

Originally Posted by gezpacho

is my fuel door supposed to pop open? i searched for a botton for quite a while gave up and just opened it by prying it open with my key. just curious but is that little turning thing on my dash under the left hand side of the gauges a windup for the dash clock?
thanks for answering all my questions.

The fuel door does not pop open, it should open if you push on the hinged end. It also locks with the doors, you can see a small pin at the back of the opening.

[gezpacho]

yeah i figured out the feul door thing this morning. i did plug the the line to disable the locks and now it shifts a little lower and more consitently but still a bit hard. i think that it might be the modulator valve. does anyone know of other areas besides the locking mechanisms that are more prone to leakage than others and are not essential to have plugged in? i also realized that this car has only 67hp!!!! it moves quite nicely though! every mention that i came across said that this car was too slow for its own good. but if you push it, it goes well. i've actually been speeding more than in my little turbocharged merkur xr4ti. i mean the benz doesn't accelerate like the xr4ti at 70mph but who really neads to accelerate hard at 70 anyway. even if it has a few problems i love my diesel mercedes. now i know why people that own them either sell them for a lot or not at all. this isn't a car i'd like to get rid of either. back to the modulator thoguh, it looks like it is sort of a wingnut type fastener or some odd wrench in the picture that mercedes shop had and under my car. is there any specialized tool that i need to remove it. it looks plastic so i don't want to force it out. if so where could i get one of these whenches and how much? the picture looks like there is a key of some sort. is that a removal tool that is included? also i have heard mentions of some people changine ALDA settings or something is this the cars computer? could i use it to fine tune the transmissions shift points via vacuum? thanks for your time and patience.
bye
juan

It sounds like you are making progress. If the tranny is shifting at the correct rpms, but still shifting too hard, the problem may be the modulator (or you may still have a small leak someplace). Before you replace the modulator, you should try to adjust it. Do a search in this forum, and you should find lots of info on adjusting (and replacing) the modulator. You also want to make sure the vacuum line to the modulator isn't clogged.

If you want to recover your door locks, it's a matter of troubleshooting to find out where the leak is. In general, the way the system works is that the driver's door is manual and the other 3 doors, the trunk, and the fuel door are slaved to it. There is a vacuum valve in the driver's door that goes to the locked or unlocked position when the door is locked/unlocked. The other doors, the trunk, and the fuel door each have a vacuum actuator with two lines connected to it. These actuators tend to develop leaks in their diaphragms. There are posts in this forum that give detailed procedures for troubleshooting, or you can just start taking the doors apart and checking each of the actuators for leaks. They cost about $40 each to replace. If you don't care to fix them, you can just leave them disabled.

Originally Posted by gezpacho

also i have heard mentions of some people changine ALDA settings or something is this the cars computer? could i use it to fine tune the transmissions shift points via vacuum? thanks for your time and patience.

These cars do not have computers. Actually, the ALDA setting is on turbo engines and has to do with adjusting the fuel mixture. Your car (non-turbo) has a ADA adjustment, which has nothing to do with the tranny. The ADA is used to adjust the amount of fuel injected. I would recommend that you solve the vacuum/tranny issues before you start adjusting anything else.

[gezpacho]

good call. i'll stick with trouble shooting before i start to fiddle with every thing else. should i just use shop air and a blow gun to clear the hoses once i disconnect them?