ScottW911

OK, so I've been around here long enough to have read about, experienced and advised on most of the issues involving our C32's. This one has me perplexed though.

Months ago, while I still had warranty on my car, I had brought to the attention of the dealer that my car was starting to chirp upon application of the throttle, from a stop. The advisor passed it off as "just your compressor kicking in" and said I shouldn't worry about it. Well, 2 nights ago, I'm stuck in stop-and-go traffic on the freeway. I had manually shifted into 1st when stopped and was rolling at speeds between 0 and 20 mph. The strangest thing happened at about 2900 rpm. If accelerating slowly, the chirp was loud and the entire car jerked, hard, for a split second. I have been able to repeat this chirp-jerk by stopping or slowing to a few miles an hour and holding the revs past the 2900 rpm point.

Remembering that I do not have warranty anymore, I wish to avoid being raped by the dealer right now. I am looking to see if anyone knows what this might be and if it might be a DIY job. My fear is that it is S/C related because of the 2900 rpm thing (I understand that is where the s/c kicks in under light load). I also fear a tranny issue, due to the jerk (the dealer said I did not have the Valeo issue with my car, by the way). Oh yes, the chirp is annoying as hell.

Anyone experience this before? Any suggestions?

sales@eurocharged.com

Sorry to hear about your troubles.

Can you try to duplicate the issue without the SC? Unplug harness from the clutch and try to do it again. Let's see if it's tranny or SC Clutch related.

If it's the clutch on the SC, I might know where you can get one for a good price.

ScottW911

Hey Jerry, I'll give that a try if I can figure it out. Looking at the s/c should the harness be obvious?

I am not able to stick my head under the hood right now (huge day) and will need to give it a try later tonight.

Thanks.

msheredy

I too can get my car to "perform" that. I took it to the dealer and had them drive in it with me. Luckily for me they had another SRT in for service and I talked the SA into taking it out (him driving) and it did the same thing. As you said only in 1st and when you accelerate slowly.

Now try this out. Put your car into 1st. Only this time when you take off, do it more aggressively. I bet once your car gets to the 2900 RPM it won't jerk. I believe it has to do with the ECU/engine load/rpm and the relationship that all of those points have with one another.

sales@eurocharged.com

Yup, the connector is to the left of the clucth.

You can see it in this pic.

http://www.renntechc32.com/variouspr.../DSC01202.html

jacek9478

Elmo the SA.



Sorry Jerry, I had to do it when I saw his smilling face.

sales@eurocharged.com

Did you ever get that pulley from ebay?

ScottW911

The car does not jerk under heavier load. The chirp, however, is still present upon application of the throttle.

msheredy

I wouldn't worry about it too much. It is strange though, thats for sure!

jacek9478

NO !! I got outbid last second.
I'm saving for LET.
and some more

Fifth Ring

How do you hold revs PAST 2900 rpms while slowing to a few miles an hour? Even in first gear 2900 rpms is going to be 20-30MPH.

ScottW911

I don't hold the revs while slowing. I stated that it happens when accelerating under light load. The jerk/chirp happens when I reach 2900 rpm, somewhere around 20 mph.

splinter

Sorry to see yours is doing it too, ScottW911. These cars are just not aging very gracefully. My family and other passengers have noticed it in ours for a while, but being half deaf, I've only been able to hear it recently. It must be getting worse, so I'm determined to find a cure without having to fork over a semester’s tuition.

I suspect it is the friction material (80/5) that has finally succumbed –




A theory as to why it is most noticeable during low load ~2900 RPM transitional situations is because when driving normally, e.g., on the throttle, the clutch is locked up long before the always-engaged threshold arrives. When the crank is rotating at 2900 and the supercharger gears are stationary, it imparts a substantial (near-instant) load to get them spinning at matching speed. The clutch takes the brunt of the abuse. Of course, the supercharger rotates much faster than the crank due to the pulley ratios. An analogy might be a drag racing start. By side-stepping the clutch in a manual transmission car along with some healthy revs, drive train shock and wheel spin (the chirp) is sure to occur. The same shenanigans at a lower engine speed would likely result in it just chugging along without all the drama.

The chirp has been discussed by the E/S/SL55 contingent. MB has a 113 098 00 40 replacement clutch that they use for warranty jobs and goodwill cases. I’ll order one to see if it can be made to work for us.

c32used

Hate to hear that you guys are having issues with your C32s kind of scares me though as my C32 ages

ScottW911

OK, so I just got home (at 9:20 pm) with too much wine and beer in my system to seriously look into disconnecting the harness tonight. I'll give it a go before I leave for another busy day, tomorrow. I think I could see the connection but my garage is poorly lit. I, on the other hand, am lit quite comfortably, thank you very much.

ScottW911

I was really hoping you would chime in on this one, John. I can always count on you to have a very intelligent and technical response (as do so many members here, like Jerry).

I am hoping to verify something soon. I keep you posted.

Sorry about the deaf thing. Is it in your right ear? I just thought that might be the side your wife sits on.

sales@eurocharged.com

+1 John is awesome!

Keep us posted.

c32used

Glad to hear you are having fun in this I have always hated car issues and can only hope by the time my warrantee gives that all the common and not so common issues are over with so I won't have to spend on repairs and continue to just buy whatever I want for car instead...I hope the good feeling you had that evening didn't mess your morning up...

ScottW911

No residual effects. It wasn't that much really. Just enough to be to lazy to turn the car around in the garage and get some proper lighting. All was good when the alarm went off at 5:00am.

ScottW911

Jerry and John, you guys are geniuses.

Jerry, I did as you said (thanks for the photo, it made everything simple) and found that, besides having absolutely no power whatsoever, the chirp and non-tranny induced jerk were gone. I plugged the harness back in and, pow, chirp! Jerk!

John, your analysis makes perfect sense here. My car was much smoother on acceleration (what little there was) without the s/c clutch junk.

So, Jerry, you mentioned a "cheap" fix. Can you fill me in? Is this DIY? I'm not driving 2000 miles for help though. I just thought I would say that before you offered to help me with the work.

splinter

Scott-
I still haven’t received the part. Should be in from the regional warehouse next week.

Didn’t want you to think I’d forgotten about it. chirp chirp

TemjinX2

here's whats posting on c32life

Chirp Sound when initially accelerating or shifting gears

Just noticed a short squeak (birdlike) sound that comes from the engine when I accelerate from a stand still. I'm not flooring it, just accelerating from a stop or slow roll. Sounds like a belt slipping 'chirp'. Could be belt or the supercharger?? Don't know, just trying to isolate sound before I take it to dealer. Had to turn off radio cause it's ever so slight until you hear it then it's annoying.

This sound also happens when the car downshifts sometimes.

It sounds like a belt is slipping but seems to be coming for the transmission.



Solution: People have had fixes from tightening the pulley to replacing the whole supercharger. There is no one single solution.


Jerk or (slam) around 1,500rpms



Put either your C32 or SLK32 in W mode.

Then accelerate slowly like you are window shopping, but keep the throttle steady and let the rpms climb.

When the rpms pass around 1,500 I get a jerk. It feels as if the car just changed gears...but it didn't. It's still in second.

Do any of you have this? Is this the torque converter engaging or the supercharger? I thought the supercharger only activated under heavy throttle.

Sometimes the jerk is almost a slam. When the car is cold I can hardly notice it.

If you have this symptom please email me.

Solution: This seems to be normal for 2002 C32's. The torque converter is locking up at around 1500 rpms. There is a computer software upgrade fix. Ask your MB dealer to put the 2003 C32 software in your 02 car.

ScottW911

Thanks for the update John. I already knew you would not have forgotten about it. I am curious to hear what happens.

By the way, after I disconnected the s/c clutch and re-connected it last week, my car feels a bit smoother on acceleration. Hmmm.. It still chirps though.

ScottW911

These are 2 distinctly different problems with the C32. The tranny jerk is well documented in other threads in this forum. I have had much work done on my transmission to eliminate the 1500-1700 rpm jerk, all to no avail.

This chirp/jerk is definitely s/c related, as I found after disengaging it at the harness. With the s/c working normally, I will experience 2 jerks when rolling from a stop, one at 1700 rpm and another (sometimes) at 2900 rpm. This is the speed that the s/c engages if we are drive at less than 44% load.

As Splinter and Jerry so eloquently stated before, this one is a supercharger clutch issue. That sucks.

splinter

Scott,
I’m sorry, but the dimensions of the M113 S/C clutch are such that it will not work in our cars, even with the adaptor bushing I’d envisioned.

Friction material as pilfered from the E55 section-

.
photo credit BrianS

That PM I sent regarding replacing my belt and tensioner was a woefully short-lived and incorrect solution. I’ll dissemble the clutch to check for contamination or glazing. Maybe a fluff & buff with valve lapping compound or shimming/adjusting its clearance will silence it. Fingers crossed!

You’ve been forewarned; if it’s a viable solution, another excruciatingly tedious DIY is sure to follow.