Tranny Fluid leaks when not used??? - PeachParts Mercedes-Benz Forum

mroliveira · #1 11-21-2007, 01:20 PM

I have a 1996 S420 with 46,000 miles.
Very Strange......
I bought this vehicle from South Flaorida in Feb. of this year.
I live in Minnesota (very cold, snowy, lots of road salt, just plain UGLY), so I didn't want to put this perfect condition vehicle on the road in the winter time, so I drove it off the transport truck and right in the garage.
After a few days, I noticed a small leak under the car. When I checked, it was tranny fluid. To the best of my ability, I thought it was coming from the pan, so I tightened the bolts. It still leaked, so I thought I'd wait until it got warmer befor I tackeled it.
As it got warmer the leak stopped. I thought it ran out of fluid. I tried to check it, (but it seams on a $91,000 vehicle in 1996), you don't get a dip stick.
I bought a stick and checked the level and it was fine.
I drove the car all summer with no issues, now it's cold again (20's-30's) in Minnesota and....son-of-a-gun if it's not starting to leak again?????

Is there an overflow? Why only when it's COLD????

.....Any Ideas????

Thanks!

deanyel · #2 11-21-2007, 03:11 PM

It's probably not leaking because it's cold but because it's not being used regularly. When it sits seals can dry out and start to leak, and/or fluid from the torque converter drains down into the pan raising the fluid level there up to the level of a bad seal. There are some seals that can be replaced with the transmission in the car but you have to first find out where it's coming from. They often look like they are coming from the pan gasket but they're actually coming a little above the pan.

the tenor man · #3 11-21-2007, 03:55 PM

My 1987 300D Turbo did the same thing after sitting a few months in the garage...I was worried!

Then I checked out the E-Class Bible...according to Stu Ritter, after sitting for a while, the fluid will move from the torque converter to the transmission and do a bit of an overflow...(I think that's what he said)....

Just top off the fluid and drive the car...that's what I did about three years ago...and still driving.

Hope this helps...
The Tenor Man

mroliveira · #4 11-21-2007, 04:41 PM

The part that baffles me is that this seems to happen when the weather is cold. ...It begins to leak after only 3-4 days of it not being used.
All summer long, I have gone more than 3-4 days without using it and it doesn't leak?
How many days is acceptable for it to leak if it's unused?
There was a comment regarding possible seal leaking,
could the cold weather mean the seal does not seal as well because of the cold?

s500lang · #5 11-22-2007, 04:09 AM

Mr. Riviera

Are you sure that the leak comes from the transmission? In my 1996 s500 i have a similar leak from the power steering. This leak will get worse in cold weather and after long unuse of the vehicle. This is a common problem on these cars. Since it is very expensive to repack the steering box I just fill it up when it begins to groan. Maybe four times every year.

Regards

JH

mroliveira · #6 11-22-2007, 10:09 AM

Happy Thanks Giving to ALL !!!

I honestly have not checked the power steering fluid. You say it can leak in the cold after LONG unuse (mine will start small drops after just a few days). Is yours ONLY in the cold?
Mine does NOT leak one drop of anything in the warmer months.

I'll check the power steering fluid today, but it has never made any noises.

Thanks for input....

Hatterasguy · #7 11-22-2007, 12:43 PM

When I put my SDL in the garage for the winter it always leaks some trans fluid. Usualy from the front or rear main seal, both of witch I replaced. I just think they will leak a bit if they sit, unless all the seals and surfaces are brand new and perfect. The car is 11 almost 12 years old so the seals are going to be a bit harder than new.

280EZRider · #8 11-24-2007, 04:20 PM

When I bought my 280E 17 years ago, one of the repair records said, "front main seal leaking." After some investigation, I found that it was the power-steering resevoir leaking through the cover gasket, which is notorious for this, down onto the lower-front of the engine. Oil leaks can be deceptive.

And about 3 years ago, after topping off the transmission fluid, I took a trip during the summer. During the return, I stopped at a rest area and noticed the transmission belching out fluid and suspected a seal. After checking the level, which was still OK, I continued on home. At home I checked again and the fluid was still at the proper level - low but above minimum. I still keep the fluid up to maximum and have had no further problem. I am guessing the fluid was slightly too high after the initial top-off, and the long, hot drive caused just enough expansion in the fluid to be dumped overboard by the transmission. I had never realized that our MBZ trannies have an over-flow mechanism.