Persistent clutch issue (long description)
 

I started having a problem with the clutch in my 2.3-16 approx 1-1/2 years ago and several (4) visits to the local dealerships and 2 slave cylinders and a master cylinder later, I'm having the same problem. I'm hoping someone has some idea as to what's causing this.

The symptom is as follows:
At some point, when I go to step on the clutch pedal, the pedal will sink all the way to the floor and stay there without disengaging the clutch.

This condition appears to be temerature dependant because the conditions during which this symptom has occured is usually when the ambient air temperature is quite high (~30-35 deg. C) and the water and oil temperatures are high as well (110 deg C and 110-120 deg C respectively).

The occurence of this symptom is intermittent at first but then, over time, it becomes more and more frequent. Initially, after I manage to pull the clutch pedal back up to its normal position, the clutch will work fine (although the pedal feels a little lighter); however it will progressively worsen until i have to attempt to clutch 5 or 6 times before i am able to disengage the clutch.

The pedal feel during this occurence suggests to me that it is a hydraulic issue. When i step on the clutch, there is initially good pressure feedback. Then, at a certain point in the stroke of the pedal (usually about an inch or so into the stroke) the pressure breaks and the pedal slides to the floor.

When this first happened, I had the slave cylinder replaced. The car was fine for 3 months then the problem came back. This time both the slave AND the master cylinders were replaced. These both occurred last spring/summer.

The car was fine until about 6 weeks ago. it happened again. I nursed my car to the dealership where they checked over the clutch system, bled the hydraulics and reported that no fault was found except a little bit of air in the lines.

Approx 3 weeks later, the problem returned and they once again inspected the system, bled it and reported NFF (No Fault Found) . Tonight, I have had the SAME problem happen twice. Tonight, it almost felt as if when the pressure breaks, the pedal gets sucked to the floor. After having had this happen so often, I can feel whether the pressure will hold or if it will break and tonight, even though I pulled my foot off the pedal immediately the second time it happened, the pedal continued part-way to the floor.

the shop foreman of one of the local MB dealerships has a 2.3-16 as a daily driver as well and he cannot provide any kind of explanation save that my car must be boiling the hydraulic fluid because the can find no evidence of leaks.

I suspect that the fluid in the one or both of the cylinders is bypassing the seals, but is that the problem itself or is there an underlying problem that is causing the bypass?

It seems that temperature is a factor in this because this never occurs in cooler weather, usually only in stop & go rush hour traffic on a hot day. Could the fact that my 16v has been running quite hot for the last year have some connection? For the first 3 years that I owned the car it used to run at a steady water temp of 80 degrees C and oil temp at the same level, but now, water temp doesn't need much to exceed 100 deg C and oil temp is consistently at 110 deg or more. This has developed only in the last year.

Any ideas on where to start are appreciated as this is becoming qite annoying and dangerous.

Ideas?
 

Anyone??

Did you buy new or rebuilt clutch and slave? If you had the work done at a MB dealer I assume they used new parts from the MB part system, but you never know. The new slave I bought recently from Fastlane was a Teves, and it had the Mercedes casting number cast into the cylinder body, so it is the same as the OE part, except in a Teves instead of a Mercedes box. (The problem with my original slave was pushrod wear - about an eight of an inch, and the clutch was starting to drag.)

One possibility is air is getting into the system due to faulty hydraulic component or seal.

Another issue could be bleeding. The clutch system cannot be bleed in a convertional way - by pushing on the clutch pedal and opening the slave valve. This is okay for fluid changes, but will not purge air from the system.

When the slave or master is changed you must bleed the system from the bottom up. You do this by connecting the RF caliper bleed valve to the slave bleed valve that is open about half to one turn with a length of tubing. You then open the caliper bleed valve while someone pushes the brake pedal - just like bleeding the brakes. This procedure injects fluid into the bottom of the system and forces the air out through the top where it vents in the reservoir. Give it about a dozen pumps, then close the slave bleed valve and try out the clutch pedal.

Duke

Duke,

Thnx for the reply.

Not sure if the parts were brand new or rebuilt. it's possiblethere could be a faulty seal letting air in. That's been part of my frustration: the service advisors seem unwilling to listen to my diagnosis and consider it.

Re: bleeding.
Each time i've had work done the system has been pressure bled from the bottom up. no issues with the procedure, the correct one is being used.

Your ROs should specify parts and prices. Are they Mercedes part numbers? Ask them the source of the parts - new MBZ parts via the MBZ parts distribution system or what?

Always ask for the old parts back.

Look for signs of leakage from the master (under the dash) and slave (bottom of the bell housing. Brake fluid is water soluble and has a bitter taste. Any leakage of fluid means air could be getting in, but the problem could also be caused by an "internal leak", which will not leave external fluid evidence.

Duke

The parts had MB part numbers, so they were OEM. Whether they were rebuilt is another issue.

I got the original slave back when i had it replcaed the first time 'round, but neglected to ask for the old master.

No leaks are apparent anywhere. car is completely dry inside & out. it's been my contention that there is an internal leak based on the behavior and feel of the pedal. I suspect that the MB service department is hesitant to actually pull the units because it would have to be billed as warranty work.

I've also spoken to a couple of independants who are quite knowledgeable about MBs and they are as baffled as I.

as an aside, no one has been able to give me a reasonable explanation as to why the water & oil temp of my car is as high as it is.

I've replaced the t-stat, water pump, & most of the hoses last year. The radiator and oil cooler still appear to function properly. i'm starting to think thatt he oil t-stat is faulty.

i also had the cat removed from my car. the thinking was that if the cat is starting to get plugged up, it could be creating enough extra backpressure to increse the engine temp. so far, the temps have dropped only slightly (<5 deg. c)

Perhaps the temperature gauge is faulty.

I had a look through some MB bullitens and found something that may be relivent.

It's refering to the clutch pedal "sticking" occasionally, but It could mean "sinking" if it has been lost in the translation.

It's refering to "thermal overload on slave cylinder (formation of vapor bubbles)" which sounds alot like your problem.

Remedy:
1) remove clutch slave cylinder
2) remove clutch line
3) remove shield if present (I think it means heat shield)
4) install insulated slave cylinder
5) install insulated clutch line

Part numbers: Clutch line A210 290 28 13
Slave cylinder A210 290 00 11

This bulliten (AR29.10-P-6130A) applies to 124,129,140,163,170,201,202,208,210.

I hope this is relivant to your problem, check the part numbers with you dealer incase they are different between LHD and RHD (i doubt they are since no referece is made). Get back to us if it solves it.

I forgot to mention the overheating problem. Have you checked the resistances of your temp senders at room temp? Have you checked the temps with a mechanical gauge to confirm that it is actually overheating?

Try replacing the hydraulic line from the master to the slave, and even the one from the master to the resovour. They are not too expensive and its about time anyway, they're getting pretty old.

sinking pedal feeling
 

from your excellent symptom diagnosis, excess heat is causing the problem. Now--insulate the slave cylinder and lines. Either use industrial white woven insulation tape or some kind of flexible tubing over the lines.

change the fluid to ATE Blue (higher boiling point). Remove the radiator and have it 'rodded out' to remove the mineral scale that's causing your overheating engine problems (or replace the radiator-- aftermarket one from radiators.com)

I had ongoing intermittent problems (over aperiod of about a year) with the clutch hydraulics in my 190E which were worse at higher temperatures. You can do as search for the numerous threads to follow the whole story. This culminated in the clutch pedal intermittently staying on the floor (without dissengaging the clutch).

A new master cylinder fixed the problem. I did not change anything else apart from flushing the old dirty fluid (which I tried prior to eventually replacing the master cylinder). The clutch has been working perfectly since.

Update...
 

Alex, Thank you for the TSB, it appears that it is, indeed, the problem. However, MB Canada has never had that particular bulletin nor the associated parts in their system. It appears that the TSB and the parts were an MBUSA issue and at that, only for those in the southernmost states. Being further north Canadian MBs didn't seem to have as much of an issue.

I have the parts manager for the local MB dealership trying to get more information out of head office in Toronto for me.


Re: the overheating problem. It appears that I am in need of a new radiator (dammit). I've replaced the thermal switches and flushed the cooling system thoroughly and the car is still running quite warm.
I'll post further developments as they occur.

Thanks all for your responses.

Finally
 

After some time I've finally gotten the parts outlined in Alex's TSB (insulated slave cylinder & hydraulic line) installed. However, the weather is too cold to see if that has had any effect. I haveto admit that I wa a little disappointed when I saw the parts. I was expecting them to have a more hi-tech solution than neoprene sleeves :rolleyes: . However, I'm not going to complain.

In addition to having the parts re&re'd I wrapped the headers with exhaust wrap and will wrap the exhaust system all the way to the CAT as well. I've noticed that the oil temp has become more stable since wrapping the headers, but this could be due in no small part to the fact that it's colder out these days. I'm still going to do the radiator, but I'll wait until the weather warms up.

Unfortunately, my opinion of a particular MB dealership has gone down a great deal. Mainly because they continue to employ a service manager who is condescending, argumentative, arrogant, confrontational, and generally unpleasant to deal with. I will refrain from naming the dealership and the service manager in question but I will present the facts as accurately as I can remember them so that it can be seen that the level of service at MB dealerships is utterly abyssmal.

In my first post in this thread I indicated that the problem had been recurring for at least 18 months and MB had yet to find a solution. Furthermore, the night of my first post in this thread I lost my clutch just as I entered the Deas Island Tunnel.

For those of you not familiar with the Lower Mainland in BC, the tunnel runs beneath the Fraser River. It has a two lanes running north and two lanes running south. during rush hour, however, there is a counterflow lane which changes the configuration of the tunnel to 2+1 and 1 lanes. the tunnel is also only one of 2 routes out Delta northbound. this particular day, a truck had already stalled in the ONLY northbound lane and traffic had JUST begun to move again when i entered the tunnel. fortunately, traffic flowed continuously and I did not have to come to a complete stop in the tunnel. If I had, I would not have been able to get out again.

In any case, I was very frustrated with this problem and managed to find only one manager on duty after having called three of the four dealerships in town (they're all factory owned dealerships up here). this was after I had nursed my car to the nearest dealership where i happened to know the service manager, but he had already left for the day. None of the advisors were of any help. Neither was any of the staff, for that matter.

I spoke to a sales manager at another dealership (who i had known for about 5 years) and he advised me to have the car towed to his dealership at their expense.

To bypass a bunch of typing, suffice it to say that it was too late for the towing company to take my car because they woudn't be able to get it to the other dealership before it closed so I got a ride to my meeting downtown - that I was 45 minutes late for - and I came back for the car later that night and drove it home. It had cooled down enough to allow this. The next moring I droppedthe car off at the dealership and immediately put in a call to M-B Canada in Toronto because I wanted them aware of the situation and my displeasure at how it hadn't been handled. unfortunately the customer service manager wa saway for the week so all i could do was leave a message.

cont'd
 

So I called the dealership later in the day to see what could be done. I had already supplied them with the TSB 2 weeks prior to this time and I provided them with an additional copy. After getting bounced around the phone system for a few minutes i was put in touch with the service manager. I explained what had transpired up to this point and was surprised to find that I was being interrogated over the phone by this person. Some of his comments were:

"Who told you that you could have your car towed here?"

After I pointed out that I brought the car in myself and probably saved them some money in the process I was told "We wouldn't have paid the towing bill anyways. We would have just billed it back to you."

I was also informed that "the Technical Service Bulletin doesn't mean anything. It is not a recall, therefore we're not paying for it."

Which was later ammended to "If the parts are not covered by the 2-years parts warranty, you have to pay it yourself."

Upon being told that I had put a call in to Toronto about this issue I was told "It doesn't matter, you can call whomever you want: the decision will be made at the dealership level by me. So go ahead."

I won't bore any of you with futher details, but basically, after having PERSONALLY been a customer of Mercedes Benz for 5 years, whic does not count that 20+ years that my parents have been customers of the local dealerships, I was treated with disrespect and as if I were trying to rip off the company. This made me absolutely livid as
A) I am not an imbecile when it comes to cars,
B) I am an operations manager by trade and by training,
C) I've been a production manager in high tech manufacturing, and
D) I've worked in retail customer service for over 11 years.

I know what policies exist at MB and I understand why they do, I also know how they're arrived at because a part of what I do is business process engineering, and MIS planning. I have a high level of mechanical and technical aptitude and I wasn't asking for a new car. I was just asking them to foot the bill for the parts and labour in accordance with the recommended solution as defined by MB's own TSB. A solution that *I* provided them with. Should I not, for $125/hr for labour, expect Mercedes-Benz to provide the solution rather than having to try to find it on my own?

In the end I had to pay $150 in order to cover the hydraulic line and the labour to re&re it. In my opinion, that's $150 more than I should have paid after the ordeal but I doubt I would have gotten anything else out of the so-called service manager.