300E Tranny Leaking
 

I recently replaced the transmission oil on my '86 300E (69.5k mi) and it is leaking oil. Here are the symptoms:

I don't think it's leaking when I am driving. If I check under the car after parking it for a copule of hours after driving, there is no leak. But if parked for 5 to 6 hours or overnight, then I can see fresh oil on the floor under the transmission oil pan.

I have tightened the pan bolts to spec and I don't think it's leaking from around the gasket area.

Are there any other places where it can leak from?

TIA.

hs

1. was it leaking oil before you worked on it?
2. Is it filled to the exact right level?
3. The easiest way to tell where it is leaking is to thoroughly clean the transmission with Gunk and a hose. Let it sit overnight and check it in the morning to see where it is dripping from. If you can't tell exactly, again wipe it clean, then tape pieces of tissue or toilet paper onto suspected parts or areas with masking tape. This is a sure way to isolate leaks.

it was leaking before i worked on it.

and it is filled to the exact level.

There ain't a whole lot of places for it to leak. Put it on the jackstands and look around underneath there with a bright light. It should be pretty evident where the leak is coming from. If it has alot of miles you may want to try a can of TransX additive. I ran a can in my 300D last tranny fluid change and it reduced the amount of leakage ALOT. If my 300D transmission ever gives up the ghost it will be rebuild time but I am going to drive it till then and change the fluid every 30K miles.

spray it with brake cleaner to get it all clean then you will see where it is. the junction points for the cooling lines can leak - mine did on both sides after a service. we checked it and found that the seals were the wrong size (my tranny had been replaced a couple of years ago)...

Why do Transmissions Leak After Tranny Oil Service??
 

I just had my '91 300E front flex disk replaced. While I was there, the mechanic said that I should probably have a transmission fluid service/replacement as it appeared the fluid was old. Not knowing when the last time was that the transmission oil was replaced, I agreed and now regret it! When I drove it home, I noticed a small puddle of fluid underneath the car under the transmission torque converter. I asked the mechanic about it and he said that it was normal due to having to remove so many items during the whole process but that the leaks should stop after no more than a couple of days. I remembered that the day after the initial transmission service, I checked the fluid level when hot with engine running and found that it was about 1/8 inch over the top mark. About a week later, I checked the fluid again and it was in the middle mark. Ironically, the transmission now doesn't flare at all, shifts perfectly and has never been better but the leak now makes me nervous. I took it in today and the mechanic stated that it was probably that the drain plug was loose and to drive it around for a while to see if it starts leaking again. Otherwise, the O ring and seals need to be replaced. Why is it that I read here that as soon as someone takes in their car for a transmission service, a very common problem afterward is fluid begins leaking?? Is there a common mistake made during the process? My 300E is a 2.6 litre, but I had it debadged and wonder now if they accidentally used parts for a 3.0 litre instead? They said that they could also tell that my original transmission had been replaced in the last 2-3 years and that a smaller than normal transmission was used in its place.....what does that mean?? A 190 tranny perhaps??

Help!

The 88-92 TE's apparently used two trans., 720.320 and 720.358. I don't know when they changed the models. Look at the front right edge of your trans to tell which one you have or if you have a different one.
Frankly, if your trans. is shifting better than ever with no flare but a bit of a drip, I'd be quite happy as trans. fluid is cheap and easy to add.

Hi. i have a 1987 260E and it is leaking oil from the junction where the engine meets the trans. i was told that the engine seal and the trans front seal need to be changed. The leaking is not too bad, so i have putup with it for now.

tati

can anyone tell me what is a "wheel bearing dial indicator is".

Thank you,

Tati

All three of ours will leave drip marks... maybe I need to add a bit every 6-12 months...

somebody once said.... if a mercedes ain't leakin', it must need oil.

I do have to admit that leaks are a weak spot on these cars... I would say a true weak spot, because they are very difficult and costly to fix in many cases.... especially transmission and head gasket.

If it is leaking on the passenger side, you might want to check the large o-ring behind the large round cover that is held in place by a snap ring on the side of the transmission. This cover is the one closest to the rear of the transmission. My 190e had a leak there and I replaced the o-ring without taking the transmission out. Wasn't easy though. It fixed my leak. Hope this helps.