You must have a ruptured diaphragm in the modulator. Vacuum should be confined to the modulator itself. There is no other vacuum connection at the transmission.

A new modulator vavle should solve the problem. Buy a new pin while you are at it. Chances are good that the old one will break, if you have the plastic version. Then change the engine "fluid" and filter.

http://catalog.peachparts.com/RenderScriptTemplate.epc?_cmd=epccat_VehicleAAA&cookieID=2G51AXQU82GY184T6Z&yearid=1982@@1982&makeid=MB@@MB@@X&modelid=300%2DDT%2D001@@300D++Turbo&catid=J@@Transmission&subcatid=J5020@@AT+Modulator+Valve&mode=PA&subcatid=J5020@@AT%20Modulator%20Valve&applicationid=000010721&source=www.peachparts.com&clientid=catalog.mercedesshop

97 Mercy, you are correct, the vacuum pump "dumps" all the air sucked out of the vacuum system right into the air cleaner.

That explains the fluid in your air cleaner, that is the only way any fluid is going to get in there besides it sucking in water (rain, carwash) or the EGR (which makes more of a soot black paste crap)

How on earth would the vacuum system vent the ATF into the crankcase guys? It should burn instead of being pushed into the crankcase by the positive crankcase ventilation system, shouldn't it?

Which vacuum line are you talking about? If you pull the line right off the modulator (passenger side of most trannys) and it has fluid in it then you know it's the modulator.

Not on a 1982 300CD. That model should have a reciprocating vacuum pump which vents into the crankcase.

On a 1982 300CD, the modulator valve is on the driver's side.

I was thinking about a 240D, sorry about that tangofox007 is correct.

Exact same thing happened to me about a 2 months ago and a new tranny modulator fixed the problem.

On a side note, I did an oil change after that so I can get rid of the "tranny-fluid-contaminated-motor-oil" that I have in my engine, and guess what.....Mobil1 synthetic transmission fluid flushed the soot in my engine. Believe it or not, the new oil that I put didn't turned black until the 2nd week since the oil change, usually the oil turns black right after the first start up right after the oil change while checking for leaks......

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'85 300D Turbo - CA Version

Thanks everyone for helping me diagnose the problem. I am going to order the part online and then have an indy do the work for me on this one. I will post again after the work is done and let you all know how it went.

So is this the pin I should order? http://catalog.peachparts.com/item.wws?sku=J5019-74125&itempk=68961&mfr=&weight=0.01&cookieID=2G51D862K2GZ1A3ZRL&source=www.peachparts.com&clientid=catalog.mercedesshop

And if so do I use it with the modulator you posted above or with this one?
http://catalog.peachparts.com/RenderScriptTemplate.epc?_cmd=epccat_VehicleAAA&cookieID=2G51D862K2GZ19ZJXO&yearid=1982@@1982&makeid=MB@@MB@@X&modelid=300%2DCDT%2D001@@300CD++Turbo&catid=J@@Transmission&subcatid=J5020@@AT+Modulator+Valve&mode=PA&subcatid=J5020@@AT%20Modulator%20Valve&applicationid=000010734&source=www.peachparts.com&clientid=catalog.mercedesshop

Thanks again

Been there, done that. My 82CD did the same thing earlier this year.

Read up on setting up the trans, before doing this yourself.

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81 Mercedes 300SD 289k.......SOLD
82 Mercedes 300CD 252k......slow ride

82 mercedes 300 SD...mi Unknown
83 Mercedes 300D ????ksniff..gone too
84 Mercedes 300D 148k........SOLD
85 Mercedes 300TD 386k and holding some one elses project

My '82 300D has the 722.315 transmission and uses the green mod valve and the pin as listed above. Just to confirm, you might want to check the transmission listed on the vehicle data card (block 7) or take a look at the actual mod valve to see what color you have.

Where do I find the tranny #? I looked in the maintanance book and the vehicle data card is not attached. Where can I find it on the car?

Thanks

If your transmission is original, you should have the 722.315. According to some sources, the 722.416 was used in the '85 Califiornia W123 models.

The easiest thing for you to do is probably look at the current modulator. If it's green, order a green one.

Hello everyone,

I bought the modulator and pin online and just had the work done at Erol's Autobahn in Nashville TN. $40 in parts and $105 in labor...not bad at all!

Mechanic told me about a separate problem that I would like to run past fellow forum members... He said that their is a separate vacuum line that is sucking break fluid out that is connected to the transmission?!?

He said that I had a small leak at the front and rear tranny seals and that if I wanted he could drop the tranny and change the seals and fix this vacuum line at the same time.

Any idea what line he is talking about? Any way to fix without dropping the tranny? Seems like if I am going to have the tranny seals replaced I might as well have it rebuilt while its dropped out...what do you guys think?

In order for that to happen, the brake master cylinder would have to be leaking brake fluid into the brake booster. The transmission would not be directly involved.

Have you observed any transmission fluid leaks? That sounds like it could be part of the mechanic compensation enhancement program.

That is possible. I had not noticed, but he said it was a small leak, so I am going to put some card board under it to see anything is leaking.

As for that break line....I could not really understand what he was talking about. He said that there was a break fluid being sucked into the crankcase and that the line was connected to the transmission...I am not sure... does that like anything based in reality?

For starters, the entire vacuum system is interconnected. The only possible contact with brake fluid would be associated most directly with the main vacuum line that runs from the vacuum pump to the brake booster. Even then, in order for brake fluid to enter that line, the master cylinder would have to be leaking from the rear shaft seal into the brake booster. Which is possible. Are you loosing brake fluid? If not, I would be a little suspect. If you are so inclined, take the master cylinder loose from the booster and see if there is any fluid present.