Hi All!

Not too long ago I purchased a 2004 CLK 320. The car now has 99K miles. I've mostly owned manual transmission sports cars so know very little about automatic transmissions (let alone MB transmissions).

Issue 1: For on/off ramps I generally tend to shift down to 3rd gear (force of habit I suppose). When in Drive and I double tap the gearshiift lever for 3rd it seems to take an inordinate amount of time (around 1.5 to 2 seconds) before 3rd gear actually engages. Is this amount of time design/normal... or an indication of a transmission problem? Issue 2: There is a subtle but distinct whine in 2nd gear (I generally drive in 'S' mode). When I test drove the car before buying I did not notice the whine. Issue 3: While starting out in Drive, occasionally the transmission 'sticks' in 2nd gear and won't automatically upshift necessitating manual upshift into 'D' This has occurred about three times in as many months.

Except as noted, when in 'D' the transmission seems to shift smoothly between all gears.

The previous two owners seem to have taken very good care of the car based on its overall condition but I don't have maintenance records. My understanding is that recommended transmission fluid changes are every 39K miles.

Would appreciate any opinions on whether a transmission fluid change might help alleviate the above issues. Also any opinions (given the limited info) on the probable general condition of the transmission.

Thanks much.

Btw, this is my first post on MBWorld so if I'm not in the right forum or whatever please let me know.

 

Hi emansnas, welcome to the forum! Please take a moment to update your forum user's profile and add your location (at least country) as this will help others to better help you.

The delayed shifting with the TouchShift is normal. It's not an "automated manual" or SMG, it's a regular automatic transmission that is hydraulically operated and uses internal clutches, ring gears, sun gears, and drums to alter the ratios. It takes time to get things moving in there so a perceptible delay when demanding a gear change with the TouchShift is normal. However, the whine and the sticking in 2nd don't sound normal. If it stick in 2nd and you cannot force it to shift, then it's in limp mode. That may clear with a restart, but will come back if the problem recurs. My advice is, if you intend to DIY, get a good scanner that can read the car's proprietary systems. SDS (Star Diagnosis) is the official MBZ system, but it's complex and more expensive. Other tools that are cheaper and easier to use include iCarsoft i980 and MBII, as well as the Autel MD802 Maxdiag Elite. Don't bother with cheap generic OBDII scanners as they only read engines codes.

This transmission is very well mad and will usually last a "lifetime", but there was one common problem with it that is usually an easy fix. The electrical connector that attaches to it has a rubber seal on its bushing that will leak. Sometimes you get a puddle on the garage floor, but you might also get fluid in the control module. It's easy to check the TCU for fluid intrusion. It's located int he cabin, under the passenger footwell. Just pull down the carpet and remove the foam insulation panel. Then you'll see a metal "cage" that is held on with a few plastic nuts. Remove that and the TCU is inside. Check the wiring for oil. If it is oily, then you need to replace that seal on the connector, and also thoroughly clean all oil from the wiring harness and inside the TCU (take housing apart to clean it). There's lots of info on the forum about this "pilot bushing" and fluid in the TCU. If you don;t find it here, also check the W203 forum as that is basically the same chassis as the CLK, just in 4-door form.

 

Hi Rodney, I very much appreciate your fast informative reply and the additional detailed info (very good to know). Actually, it's a bit of relief to know the delayed downshift is normal and your explanation of same makes perfect sense - just means I have to plan ahead a couple of seconds, no problem. I used to do extensive work on my sports cars but no longer have shop access nor at my age much inclination. I *will* however check out the TCU for fluid intrusion - very valuable tip. Right now the subtle whine in 2nd, especially in light of your transmission durability statement, doesn't seem too alarming and I suspect the previous owners exclusively used 'C' mode which maybe helps explain, since that may stress 2nd gear. So, I'll have the transmission fluid changed - don't know if it ever has been - and see how it goes over time and share whatever I learn here. Thanks also for the tip on my profile - didn't realize the defaults contained info most would probably rather not share.
Mike

 

Mike, one thing you might look into the the SprintBooster. This device offers better synchronization of the drive-by-wire throttle system and can really make the car feel more responsive, although any gains in actual performance are unproven. This can actually help with delayed downshifts, too. Since you are a sports car fanatic and DIYer, this might be an easy upgrade (it's plug and play) that you'd enjoy. I don;t have one myself (yet!), but everyone on the forums that adds it sings its praises.

 

Rodney, I appreciate your tip on the SprintBooster, perked my interest. So I did a little research (always interested to know how things work). Based on what I've read (especially here: https://outbackjoe.com/macho-diverti...s-it-worth-it/), apparently the SprintBooster's functionality is to amplify the voltage from the throttle module to the ECU by a factor of about two until maximum acceptable voltage to the ECU is reached. I.e., once one has depressed the accelerator about halfway that's all there is, and that would mean that throttle pedal travel is effectively reduced by about half as anything after that apparently sends no higher voltage to the ECU. I no longer track or race but when I did I was keenly aware of the need for fine throttle control (e.g., decreasing radius turns) so the SprintBooster may not be for me, but I can imagine the value to others. And, in spite of a hard wired predilection to increase performance, I'm 'trying' to keep the CLK stock, this in no small part due to being pleasantly surprised with the car's competence in turns at speed (limited body roll, good feel handling characteristics and typical German high speed compliant suspension). My understanding is that my 2004 comes stock with the series 1 CLK sports suspension package, but you probably know better than I. It also has the five spoke alloy wheels (I *think* OEM p/n 2094010502 for front 16") whose design and hardcore functional look I'm quite taken with. Kind of curious as to whether these are possibly forged alloy (look as if they could be) but have found no info. Probably unlikely and in either case they appear pretty sturdy.

Again, thanks much for the previous info, invaluable when one needs it. Btw, I still own a modified high boost somewhat street legal Porsche 931 (924 Turbo, my old track car) for those occasional times I feel the need for some back country twisty road 'juice'.
Mike

 

This might give better info on what the Sprint Booster does:

https://www.bing.com/videos/search?q...1&&FORM=VRDGAR

It's not just a voltage amplifier. It causes the throttle butterfly to open faster, and that is really what gives it the boost and potentially a real-world increase in performance. You can get the same things with an ECU tune also, but the Sprint Booster is much less expensive.

Post your VIN and I can lookup your data card in EPC and tell what options you have.

 

Rodney, Watched the video (thrice) from the link you suggested. Interesting. I imagine that when manually downshifting that the ECU itself matches engine RPM to the selected gear before changing to it (more delay but I would hope so for transmission wear and tear reasons). If this is the case, I wonder if there is a feedback signal to the throttle module and if so how a SprintBooster equipped car might handle that (maybe a good question for SB engineering).

Much appreciate your offer to look up my car's options. VIN is: WDBTJ65J14F098729.

Thanks,
Mike

 

My guess is that the SB does nothing with transmission gear changes - It only actuates the throttle butterfly based on throttle pedal input. I fully intend to get one, I just have not set aside the $300 for it yet. Something always comes up that drains my discretionary fund - sod, mattress, daughters...

Oh, here's your data card:

http://benzbits.com/datacard/WDBTJ65J14F098729.pdf

Your's does have the "sport" package.

 

Thanks much Rodney for supplying the data card link. Very good to have. At this point the car suits me (not so aggressive these days) and I plan on keeping it for quite awhile. Spent six months looking/waiting for the right series 2 model to show up, quite a few convertibles available (no surprise here in the NW where one can only enjoy them maybe a couple months per year) but sale of hardtop CLKs is locally rare. I'm taking that as a good sign.

Yeah I hear you on discretionary funds and I find my bookeeper (me) sometimes tends to get a bit sloppy about which fund is which. After you install the SB and have some time with it I'd be interested to know your experience/opinion.

Thanks again,
Mike