mohdds

Does life go south after 50 (or more specifically after 50,000 miles)?

I have a U.S. spec 2007 CLK550 cabriolet with all available U.S. options except the motorized rear trunk lid, which I purchased brand new in 11/2006 with 16 miles on it. It has been meticulously maintained by the dealership until the warranty ran out, then was maintained by a well known and respected independent in SoCal who for several years was the service manager at a Mercedes Benz dealership in Beverly Hills. Everything has been working fantastically until now, 6 ½ years and only 50,000 miles later, within a one month period, several problems have developed, including:

1) Command unit going bad (needs replacement as the sound output would die, the screen would blank out, so you couldn’t tell what was going on, then the unit would not be responsive to any front panel control buttons, including turning off the unit, resulting in draining the battery which was just replaced seven months earlier).

2) Driver Multicontour Seat stopped working (fuse is OK), the pump is not responsive to any of the buttons, and

3) Most importantly, engine problems described in detail below.
In addition to just wanting to rant a little, I wanted to get some service advice from some of our more knowledgeable members (I am always amazed and grateful for the information given to me by some of the members on this forum).

Over the years, I’ve owned several cars, including a 351 Cleveland Block Ford Mustang, a few BMWs, a variety of Porsches, a Lexus, a Miata, a G35 coupe, even a Hyundai, and was able to get well over 140,000 miles on most, some up to 190,000 miles, when they were eventually sold or traded in for new cars. I expected that a Mercedes that retailed for $73,545 in 2006, would hold up a little better than 50,000 miles).

Rant aside, I’m trying to figure out what’s happening to the engine before having the valve job that the dealer is suggesting for several thousands of dollars.

When I start the engine, it would run fine for about 5 minutes, at which time, if the RPM’s are in the 1,800 to 2,000 range, especially under “load” (accelerating into traffic or onto a freeway or going up hill), the engine will hesitate, then run very roughly at anything below 2,000 RPM, but particularly in the 1,800 to 2,000 RPM range (it seems to run more smoothly above 2,000 RPMs). The engine idles very, very roughly, in some cases stalling out (potentially very dangerous). The engine would occasionally “stumble” when at freeway speeds, causing the Multifunction Display to display “ESP inoperable” and “Speedtronic inoperable”, and the Check Engine Light (CEL) would come on. Occasionally, the engine would stall and die when at idle at a stop light. At this time, the battery also died and had to be replaced (the battery was less than 8 months old at the time, but was probably drained by the Command problem previously mentioned).

My independent Mercedes service guy got some OBD codes (I don’t know the specific codes) that he responded to by replacing the coils, spark plugs and the engine r/s magnets on cylinders #1 and #2 and the tdc sensor. The engine problem went away for about one day, then returned, although the severity of the rough idle and severity of the engine “knocking” between 1800 and 2000 RPM decreased significantly, and the engine no longer stalled. Also, the “ESP inoperable” and “Speedtronic inoperable” messages have not reappeared since he replaced the coils and plugs on cylinders #1 and #2. But the problem is still there with the rough idle initiated when the engine is accelerated under load at 1800 RPM.

The weird thing is, if I turn off the ignition for a couple of seconds, then turn it back on, the engine works fine again and sometimes the CEL will turn off, until I get into the 1,800 RPM range again, at which time, the CEL will come on if it was off (if the CEL did not go out when the ignition is turned off then on again, then the CEL will blink off and on when the engine “stumbles” again and starts to run rough again, then the CEL will stay on).

I did not know if these were the symptoms of the dreaded idler gear problem. At any rate, my VIN is WDBTK72F17T079526 which I believe puts the engine number outside the range of the infamous idler gear problem.

When I brought the car back two days after he first worked on the engine due to the continuing problems, my independent guy had a friend of his who is a current dealer service manager come to evaluate my car and to take a look at the OBD codes since he was still getting codes on cylinders #1 and #2 (he did not tell me what specifically the codes were, just that cylinders #1 and #2 were involved). The dealer service manager stated that in his experience there were problems with the 273 engine with “the valves sticking”. He said he had seen this before, some at as early as 30,000 miles. He stated that the engine would need a “valve job” but would NOT elucidate as to whether this was related to the idler gear problem. He did say it would be several thousands of dollars (about $5,000 to remove the heads, fix everything and run two oil changes) and as the car was out of warranty, even though this was a “known issue”, it would not be covered. My independent guy tried to talk the dealer guy into covering this as my independent guy (who was also a dealer service manager in the past) stated that it was ridiculous that a car of this type which was meticulously maintained would need a valve job in 50,000 miles. Of course, the dealer guy said there was nothing that could be done since the car was out of warranty and he could not set a precedent (which I understand, but am still pissed about since I can’t believe I spent $65,000 for a car whose engine is a POS in 50,000 miles, only 8,000 miles a year!).

Anyway, my independent guy suggested that since the car was relatively drivable, that I should try utilizing Chevron Techron Concentrate Plus Fuel System Cleaner several times prior to taking my car in to have a valve job done to see if the problem would resolve. I’ve always utilized either Shell or Chevron premium gas (91 octane in CA) which I thought had industry standard levels of fuel system cleaner (“fuel detergent”) in them. At any rate, I tried the Techron Fuel System Cleaner in about three consecutive tanks of gas and it seems that the engine roughness is slightly less pronounced (could just be that I’m getting used to the rougher running engine when it happens) but of course, the roughness still occurs when the engine is under load at 1800 RPM (then continues to run rough at all RPMs under 1800 RPM until I turn the ignition switch off and back on). I’m worried that putting off getting the engine actually fixed will cause further damage.

Anyway, has anyone experienced or heard of this happening?
Also, why would turning the ignition off then on again, immediately cause the engine to run normally (at least until its placed under load again at 1800 RPM)?
Will utilizing the Techron Concentrate cause more damage by waiting for whatever the dealer wanted to do to the engine?
Could the problem with the battery needing replacement somehow cause electronic problems to the engine management system (all these problems occurred within a period of a couple of weeks during which the battery died and had to be replaced due to the problem with the Command head unit) or is this (most likely) just a bizarre coincidence?
Is there anything that can be checked short of doing a valve job on an engine with only 50,000 miles on it? Finally, what should I check out on the Multicontour seat (minor problem compared to the engine of course) to get the pumps working?

Hopefully some of the knowledgeable members can give some insight into this problem. Thanks in advance for any insight. Sorry for the extremely long post.

California

I'll be interested to see what the heavyweights on this forum have to say in response, but my initial response is, as a fellow SoCal CLK driver, that the dealers do not do the work specified. I.e. the work that we've paid them to do.

I'm getting suspicious that they under filled the transmission on mine after I paid for a "torque converter drain" full drain of the trans and every time I call the dealer, I get a call from their car sales department...

Rudeney

I responded over on BW:

http://www.benzworld.org/forums/w209...ml#post5811401

Glyn M Ruck

+1^ Firstly I agree with everything Rodney states including replacement of plugs & swapping out coils. Get this car onto a Star DAS & find someone who is capable at diagnosis. This is not a valve problem & you need to know whether the engine is generating a P0016 & P0017 code together which will tell you if you have balance shaft sprocket wear with resultant cam timing issues.

Some of these issues are just bad luck like Comand & Battery. Benz batteries are legendary for a life exceeding 8 years.

Please check fuel pressure at the front fuel rail Schrader valve. It should be > 3.8 bar or 55 psi while cranking. Check that the airbox is clipped down tightly over MAF. Failure to do this simple thing can do what you describe and is frequently the cause of people chasing ghosts & spurious codes to be generated. The reason switching off & on is creating a change is that it is likely resetting a fault condition that once again occurs. e.g. if you are not getting decent combustion on one cylinder due to bad spark or fuel starvation the ECU will shut down that injector.

We need enough fuel at the right time, enough air & measurement of it's flow rate & adequate spark at the right time for proper running.

Dependent on codes & conditions found by Star we might have to check:

MAF
Vacuum lines for leaks
Air filter for clogging
That the Airbox is clipped down tightly over the MAF to prevent the MAF from hunting.
Check runner flap adjuster links on the inlet manifold for breakage

CPS (done) can be intermittent dependent on temperature ~ easily checked by pouring cold water over the CPS
Plugs
Coils
O2 sensor cycling rate. O2 sensors cycling too slowly can cause engine stumble.

Fuel pressure to diagnose lazy or dirt clogged pump & filter condition.
Injector delivery (Star will diagnose ~ unlikely that you have dirty injectors as you use good fuel)

Please post Star findings so we can help you further.

Good luck!

mohdds

Again, as always, thanks for your expertise Rudeney and Ruck. You guys are amazing and have helped me in the past. I will follow up and hopefully can resolve these issues. Thanks again!

Glyn M Ruck

It's a pleasure. These are complex vehicles & frequently very minor things can can lead to frustration if methodical diagnosis is not undertaken.

Rudeney

According to that VIN, the engine is beyond the affected range for timing sprocket troubles. Besides, that failure rarely has any physical symptoms other than chain slapping noises. The variable camshaft timing system can actually compensate for the slack created by the worn sprocket.

Glyn M Ruck

I'm pleased the engine is outside the range. It is that very stretch that causes the 16 & 17 codes. There is a very good thread that shows the scope traces of exactly why it generates the codes other than the bulletin. Retarded cam timing will not cause the symptoms that the OP is experiencing. I merely mentioned it because the issue was raised.

Glyn M Ruck

For info see:

https://mbworld.org/forums/4984796-post239.html

Rudeney

Thanks for the link to that post, Glyn. I still am having a hard time wrapping my head around why a worn idler gear results in the error condition. I understand the mechanics of it, but I am just surprised that the slight wear on the idler sprocket generates enough slack in the chain that the right bank cams lag behind. But I guess it does because it was enough that I started hearing "chain slap" on mine after about month of constant MIL illumination with 1200/1208.

Akbar Service

First and foremost, do not believe the date range/VIN split on the M272/273. I have personally seen catastrophic failure from timing sprocket deterioration in engines that fall within the "un-affected" range....Proceed with caution. Believe facts. Reject theories...

Akbar Service

An archaic post for an archaic machine. In general, I see a cam/crank correlation faults generated with only a few degrees of camshaft/crankshaft deviation. For example, on most M272/273 engines, a deviation of 5 degrees is sufficient to set a fault code....