ncoupe

This is about my wife's 2003 CLK 320 coupe with 60k. The car has been regularly maintained,
except for a transmission leak that the dealer (#*$~#!!!) supposedly repaired while the car was under warranty. Apparently the repair was NOT, because the car continued having a slow leak, which I did not discover until I started doing my own maintenance. As soon as I discovered it (unfortunately not before the ATF was low), I changed the transmission filter, fluid and pan gasket, so the leak is no more. However I hear what I think is a bearing noise, especially while the revs increase from idle. The noise is present regardless of whether the transmission is in N, R, or D, but is more likely to happen while accelerating rapidly from a standing position while in D or R. The noise is very similar to a water pump bearing noise I had eons ago in my 1979 VW Rabbit, something like a heat shield rattle or pebbles rattling in an aluminum casing. I am thinking front transmission oil pump bearings. Transmission shifts fine now, although it did slip once or twice before I fixed the leak. Any other ideas? Please be specific if you can. Answers like "bad transmission" now do not help much, do they?

Thank you

loubapache

So you were sure the leak was from the pan gasket? If there is no leak now, then it must be the gasket.

There is an electric connector, just above the pan gasket on the passenger side, hidden by a protective plate. that plug is notorious for leaking fluid and it drips down on the transmission pan. There has been several updates to that connector.

Noises are difficult to describe and localize. It could be the oil pump if your fluid level was really low.

It could also be the catalytic converters making noise (my bet is on this one). Try to use a garden hose or some long stick or a garden shovel to touch the cats and put the other end on your ear, with engine running. But be careful.

If it is the cats and you are in the USA, the warranty is 8 years or 80k miles, whichever comes first. You do have to see "dealer (#*$~#!!!)" if your is younger than 8 years.

Gullwing

To test the cats, just bang on them with a rubber mallet

M-bENZ

dude you just made me worry about my tranmission now lolz we have the same car .

Andy

ncoupe

...just in case. Thanks for the info.

ncoupe

The known issue with the electrical plug above the gasket on the passenger side of the transmission is what made the dealer screw up my transmission. I bet you, when they saw the leak they said, "aha it must be the plug, let's replace it", without carefully checking to see where the leak actually came from.
And two years later I am stuck with a transmission low on oil.

ncoupe

Well, you were right. The left cat is shot. I just verified it by using gullwing's method. Now I have owned quite a few cars that I drove to about double the mileage of this one, and this is the first one to need cat replacement at 60k. I know all of you are benz guys and gals, and I am more of a BMW dude (2000 MCoupe and 1999 323iS, 1995 318iS previously - CLK 320 is wife's car), but my experience with this Merc only reinforces my opinion that Mercs of this vintage are, how shall I put it mildly... crappy cars. There, I said it. Which is quite the opposite of what I have to say about people in this forum. You are first rate, and I much appreciate your help. Onto an emissions related warranty repair! I will keep you posted.

loubapache

In terms of reliability, Mercedes are crappy. There are always some high $$$ items that fail pre-maturely and MBUSA does not know anything about them.

The head gaskets in M103 and M104, wiring harness in the mid-1990's, the cats in M112/113, and the wonderful (when they work) electronic transmissions, rusts (W210), evaporator in W140 and other models, etc.

Gullwing

Wiring harness in mid 1990s blame on the environmental natzis, the insulation was biodegradable. The cats were built by another company not MB, C, E, S, CLK, ML all had issues with them. Transmission issue is mainly the 13 pin connector, any other issues are probably flukes. Give it a few years once they go 200K on original fluid...

Each car is treated differently so sure some high dollar item can go, but they were able to fix the issues with the W220, W211, W203 so things are getting much much better.

loubapache

The conductor plate on 722.6 is a very week item. There are 4 updates to the part (one just this month).

I finally was able to eliminate the 13 pin connector issue and the speed sensors on the conductor plate are the problem for my 1997 E320. I erased a 013 code (n3 speed sensor) about a week ago and got a 109 (stored code for 013) today. So I will be ordering a conductor plate and replace it.

W211 had its share of problems. The early models had leaking Valeo radiator into the transmission and of course the SBC brakes.

ncoupe

Every manufacturer has suppliers providing most of the parts in a car. The issue is what quality control the car company enforces on the supplier, and the specs they make the supplier work to. I have the suspicion that MB wnated to cut costs when they started losing money after the Chrysler acquisistion (remember that debacle?) and they started squeezing the suppliers for cheaper parts. We are paying for that.

On another issue. Is the 13 pin connector the one that usually leaks on the transmission of my W209?

loubapache

Your transmission does use the the 13 pin connector. For a 2003, it should not be the original design but not the latest either. The part has been updated several times. There are two O rings that can fail. If only the inner one fails, then the leak is internal so you cannot see the leak.

Not to scare you, take a look at the brand of your radiator to see if it is made by Valeo.

mleskovar

Are there any problems associated with the inner O ring leaking?

Gullwing

Wow just four? Then I have a bunch of two and three in the garage. If my mom's leaks I am set.

I know some guys would cut off one tab on the conductor plate "to fix" the leaking issue.

W211 had plenty of issues. Radiator was only a year or two on some models. SBC had tons of issues, but many complaints could have been "fixed" if the salesmen explained the system to the customers. Still a PITA to work on anyway.

loubapache

If that seal leaks, then the inside of the connector is flooded with ATF. This is the 13 pin plug that connects from the transmission control unit to the conductor plate that is inside of the transmission.

Worse is that sometime, the fluid inside the connector wicks up and floods the transmission control unit via capillary action. This is not widespread but some have see it. Here is a post of mine about this issue.

http://www.benzworld.org/forums/w210...ml#post3498990

Just like the conductor plate, this connector has also gone through several updates. The updated parts no longer have the "tab". The O rings are no longer available and people need to buy the whole connector which comes with the O rings. The good news is that it is less than $10.

mleskovar

Doesn't the second O ring also have to fail to get the fluid to the outside of the plug to start the wick action?

loubapache

The male and female pins of the connector/conductor plate are closer to where the ATF is. Relative to where the ATF is, the small O ring goes in first, then the plug (although it is the last one to go in but once in, it is closer to the ATF than the large O ring), and then the large O ring..

I think the large O ring only seals the ATF in the plug so it does not leak outside. If both O rings leak, then you see fluid on the outside. That is how I understand the setup.

ncoupe

Hi all,

yesterday I took the CLK to the dealer with instructions to change the left catalyst. After I wrote my last post, I also had a check engine light on, which I attributed to the bad catalyst, but I asked the dealer to check all stored codes, and I mentioned it must be due to the catalyst. He told me a shot cat does not trigger a "check engine" light (!!??!!). Wow, I thought the only thing this light is good for is for emissions-related problems. In any case he changed the catalyst (no cost - thanks for the heads-up loubapache). He told me that the DTC's for the light were for "misfire on cylinders 4 and 5", and that it may be the plugs, the "wires" or "the coils". I have serious reasons to doubt any of these. Why would the engine start running rough only after it reaches normal temperature? There are no wires, in the traditional sense of spark plug wires, if my BMWs are any indication about these cars with individual coils for each cylinder. In any case I told him to leave the thing alone. I have only done ~35 miles with the car since I took it from the dealer with the new catalyst, and guess what, no check engine light, no rough running, the car runs perfectly. Maybe it was the catalyst after all. Does this mean that the techs at the dealer are talking nonsense. Would not be the first time. Or is it that they do that to just fleece unsuspecting customers. Would not be the first time for that either.

The bad news is that the 13-pin connector on the transmission shell has a small leak. No surprise there, given how crappy this part is. I now have to go back and read all the posts that refer to this carefully.

loubapache

Good you got the cat for free. Which one did they replace? There are 4 of them (2 on each side).

Gullwing

The misfires were caused by the cats. The cat turn and block flow of exhaust gases causing the misfire, if you had driven more #6 would have also popped up.

Left side, hard to replace the front and not the back when they are attached

loubapache

Thanks. I forgot dealers do not do welds so just bolt on the whole left side. Probably would have cost between $1000 - $2000.

ncoupe

That's exactly what I thought was happening. I haven't been underneath the car yet to actually see if they replaced both cats. The rear one was the bad one.

Now about that connector. It looks like you pull it out. Right? What about that tab that sticks out in the radial direction of the yellowish round outer shell of the connector. What's the purpose of that?

loubapache

About the connector. There is a 7-mm screw holding it onto the conductor plate so you need to unscrew it before you can pull the connector out. It requires very little torque (2.5 Nm) so just use a nut driver to tighten it.

If you are talking about the tab at the 10 o'clock position, it is for you to hold it and rotate it counter-clockwise to unlock the plug.

If you see another tab at the 6 o'clock position, that tab served little purpose (position) and the new part does not have it. Get a new connector (it is cheap and comes with both O rings).