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MB E320 1995
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149 Posts
Discussion Starter #1
Hi W124 folks!

I'm wondering if you could help me resolve a mystery leak. (W124 E320 Wagon - 1995, 140K miles)

If I use my car daily, nothing happens. The transmission fluid only seems to leak when the car is left park for a few days (for instance, I parked it on Friday, needed the car this am and found the little oily ring : 5 days ). The oil came from the right rear corner of the sump but that 's just to give you a rough location idea since I did not found any oil track.

I browsed this forum and others extensively hoping to find similar issues. I didn't. Based on the material found, I inspected the sump, the base of the filler tube, other entry port...... nothing!
Transmission has been serviced 8000 mile ago: Fluid, filter, new pan & gasket. There's no symptoms..... everything works as it should, oil level is ok (checked with running engine after 4 miles - 75 outside temp).

Any clue ? I am puzzled ......

Cheers
 

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2008 E350 4M, 2016 Audi Allroad, 2019 Audi Q5
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5,445 Posts
Sure its not coming from the bell housing? That type of drip is commonly from the front pump seal.
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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17,367 Posts
I agree with what ps2cho said, BUT I have also seen cases where a badly positioned or overtightened/uneven tightened trans pan gasket causes the same type of leak.

Start simple & cheap by replacing the pan gasket. Take this opportunity to replace the trans filter and drain & refill with a good quality conventional Dexron-III ATF. Be sure to drain the torque converter as well.

Also make sure that the plastic access plug at the very front of the belllhousing is present and intact. This plug prevents dirt and other contaminants from entering the torque converter area. With age, the plastic plug tends to get brittle and crack.
 

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MB E320 1995
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149 Posts
Discussion Starter #4
Thanks for your input. I will take yet another look underneath and pay attention to that plastic plug.
Oil, filter, pan, gasket is only 8000 miles old. I can't see the point of replacing the lot again.
In both cases - Pump seal or gasket : The logic would suggest the leak to occur when the oil is hot and under pressure ? It takes 4 days 'off work' for the oil to leak ! Strange, is it not?

F.
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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Sometimes the belly pan catches a good amount of leakage before dripping onto the ground, hence the time delay.
 

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There are two port or servos on the side of the tranny--I don't know the technical names--but there are rubber seals that detriorate. The seals cost about 2 bucks each, but replacing them is kind of a pain--one of them requires a special tool. Someone on the forum may be more knowledgeable than me about this. I have replaced one the servo seals--the easy one. A good amount of fluid can leak out of these areas if the seals aren't good.
 

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1988 "Zender" 300CE Coupe, 2009 Renault Koleos, 2007 Kia Rio Sport
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I agree with what ps2cho said, BUT I have also seen cases where a badly positioned or overtightened/uneven tightened trans pan gasket causes the same type of leak.

Start simple & cheap by replacing the pan gasket. Take this opportunity to replace the trans filter and drain & refill with a good quality conventional Dexron-III ATF. Be sure to drain the torque converter as well.

Also make sure that the plastic access plug at the very front of the belllhousing is present and intact. This plug prevents dirt and other contaminants from entering the torque converter area. With age, the plastic plug tends to get brittle and crack.
+1 under tightened/over tightened bolts - check them I found 3 had vibrated loose. Bad dog Mr Indi !
 

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MB E320 1995
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149 Posts
Discussion Starter #8
Found it!

Finally managed to isolate the issue! After 4 days parked, the leak started again, so I jacked the car up and with the help of a strong light, I tracked where the leak comes from. It's that beige plastic electric device on the passenger side of the transmission. Is this what we call a Servo? Any idea what that thing does? I can't figure out how to access there.... very tight!
Does anyone have an idea of a repair cost?

oh and finally, I tried to find that plastic plug on the front of the bell housing but could not find any...

Thank you for your help.

Franck
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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17,367 Posts
Your leak is coming from the pressure control cable. You'll have to replace the whole cable, but I think you might have to drop the trans to get sufficient access.

The plastic plug is located at the rear of the oil plan where it meets with the bellhousing. Sorry for the error. The black plastic plug is trapezoidal in shape.
 

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1989 300E 125,000 miles, 2005 Acura TL, 2011 Hyundai Elantra Limited
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201 Posts
Leaks

My servos were leaking an increasing amount of oil along with the front pump seal. Replaced with a remanufactured transmission and all is dry now.
 

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MB E320 1995
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149 Posts
Discussion Starter #12
Thank you

Thank you guys,
I'm going to open a new more specific thread based on your info.
Maybe, this will lead to some answers in regards to the repair procedure.
It definitely looks like a job for a pro and I would feel more comfortable to know what's involved.

Cheers :)
 

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600 Posts
I think this is a classic DIY where you can save yourself at least $400. I would try to fix it. The sticky with procedures probably can help you here.
 

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1989 300E 125,000 miles, 2005 Acura TL, 2011 Hyundai Elantra Limited
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201 Posts
Transmission

How much was the remanufactured tranny and where did you get it? Did you install it?
$1,650 Reman remanufactured transmission plus labor to install it by a local Mercedes Indy shop in Sacramento, Ca. 2 yr unlimited mileage warranty.

The shop made arrangements for the replacement transmission. I like DIY but I did not have the knowledge or other resources to take on this replacement.
 
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