aleks001

I have a slight weird noise and vibration from the car I can't really tell from where but it seems like its either right in the middle of the car or at the back of the car. It almost sounds like going over those rough concrete patches, it's like a humming sound best way to describe it I would say it almost sounds like one of the tyres is rubbing on something. Reading around it seems that for some people this was the transmission fluid and coolant mixing. If this is happening apart from performing a glycol test is there any other way to tell ?

I can't see an transmission fluid in the expansion tank and I also don't think there is any coolant in the transmission. When I used the dip stick to check the level the fluid was green, which I believe someone either replaced it with a green fluid. The coolant is blue so one would think that you would see some sort of foam or bubbles on the dip stick if it was mixing and red and blue wouldn't make green. Car is a 02 CLK320 and has a VALEO radiator. When this issue happens are there any easy tell tell signs, I'm at a loss at what the issue can be, it's very bizzare. Vibration only comes on very random speeds and if you accelerate even a little harder when it happens it immediately goes away. There doesn't seem to be a speed that it happens all the time although I would say it usually 50KPH and above. You can be driving at say 110 and all is fine and then you will hear and feel the vibration, you can feel it most in the seat and transmission shift knob. If I didn't know better it sounds like bad tyres but the internet has got me spooked

aleks001

Also, from what I can tell the car has a separate oil cooler in Australia, I'm pretty certain the transmission cooling lines aren't connected directly to the radiator would that make mixing impossible ?

Actually the thing I'm thinking of is probably an engine oil cooler and not a transmission fluid cooler as it's attached to the oil filter housing.

Let me also add that the transmission shifts fine, no clunking etc, sometimes it doesn't shift a gear perfectly, mainly on slow decelerating but even that is not every time, but in saying that ever since I've had issues with my BMW I'm ultra sensitive to transmissions, wife bought a brand new mazda and I can feel every gear, thanks bmw!

xsever

Check out my thread below. Same thing happened with me.

https://mbworld.org/forums/clk-class...vibration.html

aleks001

Did you end up solving it, these kind of issues are impossible to diagnose, I've been reading all day and very similar symptoms people have fixed with all kind of different results.

I'm pretty certain my issue is not the transmission the more I think about it, but you never know. I'm going to try driving and selecting gears manually on the way home today and see if makes a difference. People who have genuinely had issues with their transmission and needed it replaced had all kind of shifting issues, noises and clunks. This might be one of those things I just leave alone, sometimes it's better to let things explode then spend thousands chasing a ghost and then having it explode anyway.

I will also swap the tyres, right to left and left to right to see if the vibration transfers. I will also be doing a transmission fluid change soon anyway as god knows when if ever it was done and car now has 175,0000 km's. It is also a little low on transmission fluid. Will keep updating this thread if I find anything, keep the suggestions coming

At the moment I'm leaning towards either an issue with tyres or wheel bearings. I've been under the car quite a few times now and didn't see anything weird. Differentials usually whine if there is an issue so it doesn't seem to be that. I'm leaning towards it being an issue towards the back of the car because when it happens you don't feel it in the steering wheel.

xsever

Since you need to do a transmission fluid anyway, drop the pan and carry out the change as soon as you can before the transmission is damaged if that's the problem. When I did that, we could see the coolant mixed with the transmission fluid into a white milky cream. I would have never imagined that the faint vibration/noise would turn into this. Glad I caught it in time otherwise the transmission would have been toast.

Check out the picture below. It's not very clear but that's what was in the transmission oil pan!

aleks001

Yep, Driving home it felt more like it was coming from the transmission area. Will be doing a pan drop on the weekend. Fingers crossed my tranny isn't toast

More description on the issue. Will mainly happen when going up a hill. Trying to make the issue worse by holding the rpm and then messing with throttle i can make the vibration pretty severe, feels like something is going to fall out of the car. My car also has a valeo radiator from 2002 with a 203xxx part number. It's looking more and more like the mixing issue isn't it Checking the fluid at home again through the dipstick it is a brown/ slightly green colour. Will update when the pan is dropped I'm highly doubting it's anything else apart from the tranny at the moment.

xsever

I was ruling out the transmission at the beginning, but was proven wrong. Since you have the Valeo radiator, chances are very high it is the problem since it's a well-known defect that affected many models. In all cases, dropping the pan is the cheapest diagnostic at the moment especially since you want to change the ATF. Keep us updated and good luck.

aleks001

thanks mate will definetly keep everyone updated. If i cant tell that its mixing and the only symptom is green fluid i will just change the fluid and see how i go. If any white parts exist like your car it will be radiator and full flush time.

aleks001

Update: Dropped the pan this morning, no signs of coolant (That can be easily seen anyway, although I'm pretty sure at 170,000Km's if it was mixing it would be very obvious). There was also no weird metal pieces or anything like that, just your usual clutch shavings.The fluid came out black with a very slight green to it, which is consistent with other videos I have seen of extremely old fluid. The car now obviously requires a full flush and not a drain and fill, the fluid is so far beyond transmission fluid I'm amazed the car drives at all. Will be flushing it later today through the hose that connects to that radiator, this seems the easiest way. Just hoping now that no permanent damage has been done, but I have faith in these MB transmission so we will see what happens after a full flush. Will be using Fuchs 4134 for anyone interested.

aleks001

Update 2: Ran out transmission oil. I had 11.5L, it took 8L until red fluid started coming out!!!!!!! The old fluid coming out was brown, honestly it looked more like muddy dirt water then any type of fluid. I can't confirm if the trany was the issue yet as I didn't have enough fluid to put back in after all the flushing and the place that has the fuchs fluid isn't open till monday so I will have to wait till then. In the meantime I have discovered the following:

1. Front wheel bearings have play in them, but I doubt it's them as if it was you would feel the vibration in the steering wheel.

2. drive shaft center bearing may have some play in it. Now I've never tested one before so I dont know if its acceptable or not but if you grab the drive shaft at the front where it connects to the transmission and push it up and down quickly there is very little play but not at the back where it connects to the differential. I also doubt this is the problem because i cant see how it would make the rumble strip sound and why it would cause a little bit of drag when the rumble strip sounds happens.

Any suggestions, also will update when i get the correct amount of fluid in and go for a test drive.

Looking at some youtube videos now, it's definitely not the center bearing. Bad center bearings will make noise and the whole drive shaft will have play, i was probably just feeling some play from the transmission connections, it's probably normal.

xsever

It does take around 8-12 liters for the fluid to become clean so it's all within the norm. With the fluid you're describing being so bad, I wouldn't be surprised if it wasn't the problem as it was doing a pretty bad lubrication job. Similar to having water in it maybe? Monday will tell I'm sure.

So until you can drive the car with the new fluid and filter, I wouldn't bother looking elsewhere except for maybe the flex discs which connect the drive shaft on both ends. Can you see cracks in their rubber? Maybe it's worth replacing them now since you're already there.

aleks001

I'm honestly surprised it was driving at all that's how bad the fluid looks (I've seen other cars with bad fluid, but this is on a new level). On top of that it was also low on fluid as well. I'm pretty certain this was the original factory fluid. I don't even know how the transmission filter was letting any fluid anymore the build up that was created on the filter was insanely thick.

Flex discs are fine, inspected them first. Only thing that is cracking is the paint that was use on them, but they look in pretty decent condition and personally I think they shouldn't even be considered unless a car has done over 200,000 miles.

xsever

That bad eh? Did you manage to take any pictures by any chance? Let us see the filter at least if you still have and if you have time, crack it open and take a peek inside. I've done that before with a fuel filter to make sure the gas I use is clean and the internals were pretty clean.

aleks001

No i didn't sorry I was in a rush. I can probably get the filter out of the trash and cut it open if you really want lol

aleks001

Looked pretty much like this.
http://www.planet-9.com/reviews/data...e/IMG_0598.jpg

This link seems to describe the situation perfectly:
https://cdn-enterprise.discourse.org..._1_690x217.jpg

I can't stress enough for people with transmission that have never been serviced to do a full flush, in fact it's actually very simple. Can't believe how long it took for the brown fluid to stop coming up, it would take you probably 30 liters of pan drops and swaps to get most of it out and you would still have some in the system.

xsever

If you're curious enough and have time, go for it. It'll be interesting I'm sure.

Here is what the fuel filter looked like after a year of service.

aleks001

How did you cut the fuel filter ? I was gonna do the same but couldnt think of anything that wouldnt cause a fire lol

xsever

I used compressed air to dry it out as much as possible then a hand saw.

Manya3084

Hi,

I purchased a 2003 CLK320 with 225,000Kms on the clock. Drives fantastic, well serviced until the last year, where it looks like it's been traded in.

After looking through all the service history, I cannot see any mention of a transmission oil change, nor can I find any mention of a radiator change. (I do have a Valeo Radiator).

Before going through the hassle of dropping the pan to check if I have coolent mixing, I decided to disconnect the quick release transmission line from the radiator, and pump 1 litre of oil out and let it sit over night for water/oil separation. So far everything looks fine.

Should I just replace the radiator anyway with a Behr unit for prevention?

Any help is appreciated :-)

Thank you,

aleks001

no one can really answer this. Its really personal preference. I would say though if you plan to keep the car long swap the radiator. Otherwise i would just leave it. But there is no right answer here.

Rudeney

I would replace the radiator. do it. It's not a very difficult job.

aleks001

After the fluid change its definetly much better. I only took it for a short drive but i felt the more i was driving it the better it was getting. I’m thinking the gearbox might need a little time to adapt to the new fluid. Its definetly a lot better though you can barely notice it now.

xsever

Glad to hear it! Congrats on the new feel.

Maybe an adaptation reset for the throttle sensor will refresh things as well. (the one with the key in the ignition and doors closed and depressing the gas pedal for a specified amount of time)

aleks001

Took the car to work this morning, I normally have a a different car as my daily and it was very hard to reproduce the issue, I really had to try, if you drive it normally and accelerate normally you don't feel the shudder anymore. My engine mounts, trans mount are definitely bad as well, but since I'm planning on selling the car soon, I think I will just leave them. Will adjust the wheel bearing play this weekend just to see if it helps as well.

xsever

Did you mean that you were able to reproduce the sound/vibration but it was much harder to do so since you changed the fluid and filter?

When I replaced my transmission mount for $18 last month, I felt as if I bought a new car from how smooth it got.