1990 300E 4matic trans question...
 

First off Season's Greetings!!

Now, my trans loses fluid. It was found to have badly decayed cooler lines and so these were changed...but it still loses fluid, altho there is nothing perceptible on the underside or ground so Im stumped.

It also has episodes of huge plumes of white exhaust billows, and I have read that it's possible that if the trans modulator is faulty, it could allow for the ATF to get combusted in an engine cylinder.

So I take it to the guy who fixed the lines, and tell him to check the modulator, and his reply is, upon investigation, my car has NO modulator.. I have no reason to doubt him, he's well regarded on trannies. :confused:

Does anyone know if this is possible, and if so, where my ATF might be going????

Cheers.

Your car definitely has a vacuum modulator. It is on the driver's side and is round plastic. It will either be black or most likely red.

yes they can leak thru and get into engine

Where are you adding or checking trans fluid?
 

A 4Matic of this era that billows white smoke sounds like it has a leaking transfer case. With a transfer case leak, there is no loss of trans fluid from the transmission. Are you checking the trans dip stick and adding fluid there?

Modulator failure
 

As previously noted, there definately is a modulator on this tranmission. Its a colored plastic vacuum cell about the size of a silver dollar, The vacuum line goes directly to the intake manifold. If you pull off the hose connector at the valve and fluid is apparent then you've got your culprit. The new modulator is probably different than the original and requires some multiple part replacement, The new "pin" should come with the part. Don't completely snap the new lid back on the modulator until you are happy with its adjustment. Its designed to be left on and has an externally adjustable cover that allows a 0.4 bar pressure adjustment without removing the cover. Good Luck!

It's definitely the tranny's ATF that's disappearing. And it's disappearing at a rate that were it an external leak, it would be obvious. I have to conclude it's being consumed internally, somehow.

But to your post, how would a leaky 4matic TC cause the billowing smoke anyhow...

Thanks to all for the help.

On the 4-matics the modulator is mostly obscured by the front driveshaft. Even the simple adjustment is quite difficult with the front driveshaft in place. Replacing the modulator will certainly require removing the front shaft to gain access:(

look in the radiator the cooler might be bad as the changing of the cooler lines might have ruptured the core on the inside if the radiator has oil in it than change the rad - jz

leaking 4matic
 

On a 4matic, hydraulic fluid leaks into the transfer case (which is filled with transmission fluid). The transfer case fills, and eventually overflows spilling fluid onto the exhaust. In some cases, this causes a lot of white smoke while driving.