How do you replace a vacuum modulator on a 1990 190E?!?!? - PeachParts Mercedes-Benz Forum

lsmalley · #1 05-20-2012, 01:53 AM

Just diagnosed my recent problem of erratic idle and smoke coming from the exhaust. Vacuum modulator is bad and I watched as the vaccum hose from the intake to the modulator slowly drew in transmission fluid

. So I went and get a modulator, but now I don't know how to install it. I can't access it from under the car, even with the pan off. How do I lower the transmission? And does lowering the transmission mean taking it out completely? I'd ratcher not do that

porkface · #2 05-20-2012, 11:29 AM

do not try this with old motor mounts, you WILL have to replace them after you're done. old mounts do make it easier, though. drop the exhaust and support it with bungi cords so it won't break at the manifold. unbolt the trans crossmember and let it tilt down, with a jack, not free-fall and support it. wedge a 2x4 between the tunnel and trans. this will move the trans to the pass. side some. now there's more room to attack the modulator. good luck, chuck.

ps2cho · #3 05-20-2012, 11:38 AM

You may not necessarily need to unbolt exhaust...support transmission and remove crossmember and keep lowering until it stops and see f that is enough. As said above, use a block of wood and push trans to the side to give you more room.

lsmalley · #4 05-20-2012, 11:48 AM

hey is the cross member the part that the transmission mount sits on? Sorry never done anything with the tranny before othere than fluid and filter. Aslo what else do I need to take off to how it to lower?

porkface · #5 05-20-2012, 12:43 PM

to ps2cho-if you don't lower the exhaust, it acts as a lever to the motor and won't let it drop all the way. just remove the exhaust from the hangers and support it, don't unbolt it from the manifold. supporting it means it won't break at the manifold.

to the op, the crossmember supports the trans at the rear from left to right. good luck, chuck.

lsmalley · #6 05-20-2012, 12:51 PM

ok the cross member is the black metal piece that holds the transmission mount. I took that off yesterday and the transmission is not lowering. what else am I missing? I'm under the car now

cypress · #7 05-20-2012, 03:19 PM

If you did you not pick up the modulator from the dealer, you might not have the most updated one. Also did you pick up the the "pin", it should be replaced as well.

lsmalley · #8 05-20-2012, 03:24 PM

Everything is from the dealer. I think I need to remove the driver side motor mount because that looks like the reason my transmission isn't lowering, even with the cross member removed. I am still at it so please chime in with advice to remove. thanks

pawoSD · #9 05-20-2012, 04:37 PM

When I did it on ours.....I Just lowered the rear of the trans with the crossmember removed, as far as I could safely go, and that made just barely enough room.

lsmalley · #10 05-20-2012, 04:46 PM

cross member removed. exhaust bracket removed. my transmission is in the same exact spot. did not lower, not even marginally. car is a 1990 190e 2.6. its there anything else holding the transmission in place?

porkface · #11 05-20-2012, 05:12 PM

you have to drop the exhaust from the floor of the car, no ifs, ands or buts.

undo ALL the hangers and support the exhaust from the rear bumper with bungi cords. you are dealing with an 11 foot lever keeping everything in place.

support the trans, drop the exhaust and then lower the trans. it is that simple. good luck, chuck.

lsmalley · #12 05-20-2012, 05:26 PM

so the damn exhaust is the culprit.....thank you so much. this its going on day two and I'm in the desert.....104° right now. Will report back

lsmalley · #13 05-22-2012, 02:58 AM

Thank you all for your help on this issue. Here is the update:

First I'd like to say veryone was right about dropping the tranny a bit to gain access to the modulator, but unfortunately this does not apply to the 1990 190E 2.6 as I had the good fortune to inspect other model cars with the 722.3/4 tranny and the modulator can almost easily be reached from just going at it horizontally with an extension. I had to take off the exhaust (thanks for the tip Porkface) and disconnect the front flex disc, then I had to use a pry bar on the back of the tranny and push down on it just to tilt it by maybe 1 to 2 inches and I still had no room. $#@! the engineers who decided to make this model the worse for accessing anything. Ok, with that said, barely swapped it out and connected everything back again, but now the shifting is super soft. So I'm guessing I need to go back under there and adjust the "T" by turning it to the right....? Is that correct? and if so, how much do I turn it? I thought I was smart by looking at both the "T's" when I got the old one out and they were both in the same position and the "T" could only sit properly in the grooves with the dust cap covering one way without turning it. Also, the white shifting nut on my Bowden cable broke. Can I replace only the nut or does the entire cable need to be replaced?
Thak you all again for the help!