04 C230 Sport Sedan - Automatic - 80,000 - No issues

My car has been sitting in my garage for 3 weeks without being moved. Temperatures in the garage ranging from -5F to 40F over the last three weeks. I walked around the car and noticed this:


So I crawl under to see what the problem is, thinking to myself, this is the most oil/fluid I have ever seen leak out of any car I have ever owned!

Holding my breath, I first check the oil drain plug. It was loose, I got another 1/4 turn on it and there was a drop of oil about to drip off of it. At the rate of approx. 1 drop every 6 hours. There is no way all of this fluid came from there. I looked all over, no runs no spray and relatively clean.

I roll further under the car, nose rubbing the bottom as I slide back.....

I notice another drip on two bolts on the transmission pan and one drip on a bolt holding a metal shield over an electrical connector entering the transmission. I wipe them off and let them sit for 5 days. I crawl back under the car and notice another smaller spot of fluid under the car and more drips on the three bolts. I was able to get my finger between the connector and the aluminum transmission housing. It was full of pooled fluid.

This is the connector:


I proceeded to pull the connector out. There was fluid inside the connector only at the lowest point. (It was not full and there was not enough to run out).

I have a feeling that the plastic housing in the transmission is leaking. Here are some pictures (as good as I can get) of the housing in the transmission. You will notice where the fluid is running out and down the aluminum.





My questions:
I assume the fluid is transmission fluid?
How/Can I get the plastic housing out to replace it?
Any other ideas as to what could be causing the leaking?

Again, the car has not started up for 3 weeks. I leave her in the garage during the snow. So there should be no pressure to force the fluid out, only gravity.

Please help!

 

You can buy a new plug PN: 1402700250
Carefully remove the plug using a 5mm socket. Note the orientation of the plug and the lock ring so you know how it goes back in. Pull it out, there are two O rings. Check when you order to make sure you get the O rings. There are several good threads around for replacing... here is just one of them http://www.benzworld.org/forums/r129...g-adapter.html
Here is a good YouTube video for putting the plug back in.

As per the fluid on the floor, to me it looks like it has a slightly greenish tint to it. I don't think it is tranny fluid and I don't think that much fluid could come up and out of the connector.

I'd first try to figure out what the fluid is. I think the choices would be oil, brake fluid, TS fluid or coolant. Maybe a freeze plug popped? My guess is oil and that there is another leak somewhere on the engine. Check the oil level and see if it is low.

Assuming that you do have TS fluid in the connector you should change that. The O rings should fix that leak. Make sure you get as much fluid as possible out of the harness. Now might be a good time to flush the TS fluid and change the filter.

 

First off, thank you.

I looked all over for engine oil. I originally thought it was oil myself but the leak is too far toward the middle of the car. (Directly under the gear shifter) I don't believe it is engine oil. There is no run to the point at which it is dripping onto my floor. I have checked all over except the top side mated to the bottom of the body.

The fluid looks very much like a used motor oil (darker than clean mobile 1). I just did an oil change, less than 100 miles on the new oil) I would not expect it to look like what is on my floor. It is too black to be brake fluid. Engine oil level is good.

All of the fluid pooled up under the electrical plug housing. The housing is quite loose from the aluminum. (I can turn about 1/32 left and right). To replace the plug, should the TS fluid be drained?

What/where is a freeze plug?

 

The fluid is dripping from here:




As you can see there is no run to this location so it has to be coming only from bypassing the o-rings on the plastic housing.

 

The plug housing has O rings to keep the fluid in and will turn slightly side to side as rotational movement is only held in check by indentations, in other words, it isn't the tightness of fit that keeps the fluid in. That said, since it is a loose fit, if the O rings have failed then certainly fluid would come out.
As per changing the fluid, I don't think it would be required, however, if I were going to go to the trouble of getting the car up on jack stands to replace the plug, I would certainly drain the fluid, drop the pan, replace the filter, put on a new gasket and put it back together. If you don't already have one, grab a torque wrench that is in the range of 20 to 250 inch/lbs. You do want to get the pan bolts torqued back correctly. There are a couple good threads in the W203 forum that go over the process step by step. Refilling is a little tricky so you'll need to read through that a couple of times.

 

Any recommendations, from experience, on a good DIY for draining and filling transmission fluid?

 

Here are three videos that should be helpful.


The first video actually looks like your problem.


Same guy doing a basic drain and fill.


Last video shows an interesting technique for flushing the torque converter. I haven't used this technique and there isn't any audio, but if you look at it closely you can see that he is also flushing the torque converter by running the engine and feeding fresh transmission fluid up into the transmission and letting the TS pump it through.


Good Luck!

 

Great videos, Thank you!

Parts are on order, just need to find TS fluid that isn't $20 a L.

I am a little leery of flushing the torque converter but well see how brave I feel in a few days when the parts arrive.

 

I hear you on the TC flush... not sure how brave I'll be at the time either. All four of my cars are due this year and I'm planning on doing the TC flush like in the last video but we shall see....

 

Thought this video had a better procedure. Looks simple and clean. I am going to try this for my flush.

 

Yeah, that looks pretty easy. I guess MB recommends taking the hose off at the TS because you still have all the fluid in the line. If that line run straight to the pan you might let it drain out a little when you take it off. In theory it would be dark and the light red as it drained letting you know that fluid was out of the hose.
I do think it is important to replace the washer and gasket even if they were replaced recently. The design of those components is to give when torqued dow. The gasket might spring back to a degree but the washer certainly will not. Same thing with the oil drain plug.

 

Changed out the connector, replaced gaskets and drain/filled the pan. Waiting overnight to see if that stopped my leak. All set up to flush tomorrow just need a 2nd set of hands.... my drain bolt was/is over torqued! I could not get it to budge, snapped a 30mm torx and almost a 2nd trying to break it loose. Left it in as it is not leaking but draining the pan became messy due to all the fluid.

The connector was a pain! Spent 30 mins on my back under the car with my arms in the air and finally got it seated enough for the screw to bite.

I'll report back tomorrow on the status of the leak.