Hi everyone,

I have a leak coming from the transmission of my 2003 C240 where it attaches to the tube that goes to the radiator. I've attached a photo. Does anyone have a diagram or parts numbers for what I might need? I'm assuming it's just an o-ring or gasket. Also, will it dump all the ATF or should a quick parts swap be pretty easy?

Many thanks!

washer on that bonjo bolt may be leaking trans fluid. Not all the trans fluid will come out when you remove that bolt; only the fluid that is in that line (and possibly some of the fluid in the radiator) will leak out. Just to be safe, have 2 qts of MB trans fluid ready before you open that bonjo bolt. Take a look at the picture below... part # 90.

If the trans filter and fluid hasn't been replaced before, use this opportunity to replace the trans filter and fluid.

pcy,

Thanks so much! I'm surprised there is only 1 o-ring between the bolt and the fitting and their isn't one between the fitting the the transmission.

I'll have to swing by MB and pick up the part. Any chance you have the torque spec for that bolt?

Thanks again!

I believe that's a washer, not an O-ring. Looks like you cleaned it up real well to source the leak....is it leaking at the washer junction? Did you check to see if the bolt is tight?

I think you're right and it is a washer. It was finger tight, but I didn't check with a wrench since I don't know the torque spec. I think it is leaking at the washer junction. When I put a clean paper towel on it, I can see a little seepage.

Any idea on torque?

Many thanks everyone!

I'm certainly new to Merc's so I could easily be wrong, but I've never seen torque values for banjo bolts. If it's only finger tight, that's probably your problem. I would put a wrench on it and keep in mind that I'm tightening into an aluminum casting. It doesn't have to be really tight, just very snug. I expect that will solve the problem. In the mean time, you can get some more washers - usually they're copper or aluminum so they'll crush a little.

There is a 'sealing ring' crush washer on each side if that fitting. Ask for PN 002 271 11 60.

Specification is 5 Nm plus an additional ninety degrees. I don't have anything to measure accurately that low, so ncmudbug's “snug” suggestion is appropriate.

You guys rock! Thanks so much. I'll post the results tomorrow (assuming the part is in stock).

Mine is also leaking I tightened it a little bit and will have to check it when i get the transfluid flushed in the near future.

Puppyfrog, after you've taken care of the leak, make sure to check the level of the trans fluid and top it off if necessary.

Yup, I have the dipstick part number and ATF on my list. I'm just going to top it off since the entire transmission was flushed and filter replaced after the socket o-ring failed last year.

Hey folks,

I picked up some washers from Mercedes of Austin this morning. If anyone is interested, they have updated the part number and it is now:

007603 014104

The washers are a little larger than the ones I took off the car. Changing the part was easy and resulted in minimal fluid loss (perhaps 2-3 tablespoons worth). The original washers looks a little oblong, so perhaps there was a manufacturing defect or a mechanic was a bit rough on them in the past.

Here is a picture of the old washers (foreground) and the new (background):



However, I'm a little concerned that there is a little oil seepage in another area. Please see this photo:



This is the area to the front of the transmission. If it is leaking, it will be quite a job. Anyone else have this issue? What amount of seepage is normal? None?

Thanks again!

did you just change your atf fluid? If so what did you use?

I didn't change it and the level is good. However it was changed about 10k miles ago when I was living in the SF Bay Area. It was done by a independent Mercedes shop. That said, now that I think about it, the fluid in there isn't red like the MB stuff I just picked up. Uh oh...

I hope there isn't seal compatibility issues with the stuff the shop used. I suppose a complete flush might be in order.

Any chance you know if that area in my picture is prone to leakage?

Thanks

that looks like the bell housing... inside that bell housing, the torque converter access port is located. It's possible that when the trans fluid was changed, they may have drained the torque converter and some of the fluid may have spilled inside the bell housing. That fluid may be leaking out.

There is no TC drain plug on our model 722.6 transmission. Damn bean counters removed it in 1999. Put back on 722.9 tranny.

Just watch it. That little bit of oil could have migrated from elsewhere with under car airflow. I would not loose sleep over it.

clean the area with brake parts cleaner and keep an eye on that area and see if that seepage comes back. Then we can go from there.

Many thanks guys. I'll keep you posted and I really, really appreciate all the help.

Guys, I have a few more rookie question. Is it OK to check the ATF level with the car running AND air filter box removed. All the directions I find online seem to say that you should check the level with the engine running.

I've been checking the level after I drive the car to warm up the fluid, but with the car off. I also seem to only get one reading before the dipstick brings some fluid into the tube and makes all subsequent measurements look high. Is there a trick to doing it?

Thanks!

Trans fluid should be checked [with car on a flat/level surface] while the engine is running. To measure the fluid level precisely, the trans temp should be around 85 deg. cel. You can measure the trans temp with the use of contactless IR thermometer (available at HarborFreight store for around $20). Or, you can drive the car for about 15 to 20 minutes, and park the car on a level surface and measure the trans fluid level with the measuring tool.

About running the engine without the airfilter, it should be ok to run the engine for few minutes without the filter... as long as the car is not in a dusty area.

Where do you guys aim the IR thermometer? At the transmission oil pan?

Thank again!

right, aim the IR thermometer at the trans pan (to read the temp). It's not accurate, but close enough.

Hey Guys,

It seems that the seepage around the bell housing has gotten a little worse in the last 8 months or so. I can't quite figure out where it's exactly coming from but it seems like it it's coming from the passenger side of the housing.

I changed the valve cover gaskets and resealed the recirculating covers last winter so I'm pretty confident it's not coming from that area.

Any thoughts on what I should look into?

Many thanks!

I assume you've ruled out the "tranmission bushing" aka 'plug' that carries the wiring inside the trans? You could have a rear main leak/weep. How much does it leak? Do you wipe off the oil and check for buildup? Do you add oil between changes? Does the leak ever overflow from the underside cover and on to the floor after you clean it off?

Yes, the transmission plug was replaced 4 years ago or so and it looks dry. I'm pretty sure this is engine oil since it doesn't have the ATF color. It's not a ton of leakage since the oil doesn't need topping off.

Only a few drops in the underside cover, but there is evidence that more oil is being blown further towards the back of the car. So, I assume that the leak is happening mostly during driving while hot and the majority ends picked up by passing air and sprayed around the underside of the car.