2000 SLK 230 Comp

[jibcl500]

All

Ive been driving the wifes SLK recently and I have noticed a rev stutter at 2000 rpm, if I accelerate it stutters on each gear change at 2000 rpm, if I rev the engine gently whilst in park at 2000 rpm it momentarily stutters as the compressor kicks in (I assume)

Anyone any ideas please, other than this problem it drives fine.

jib

 

[type49]

Could be camshaft adjuster. At the very front of the engine there is a plastic cover, remove it & you will see the magnet which operates the adjuster. It is about 3-4" in diameter & is on the inlet cam side. Remove the 2 pin electrical plug & see if the noise stops. This job can be done "in situ" but requires valve timing etc & is easier to do with the inlet cam removed completely - not a DIY job unless you are very confident. I have known these adjusters to be left disconnected for a long time without any problems but I can't promise anything. Good luck!

 

[jibcl500]

I did unplug the air flow meter abd then restart the SLK and although it ran lumpy the problem wasnt there when the revs hit 2000 rpm.
I will try the timing magnet connection to see if that makes a difference, I have done some work on these engine before so I know them pretty well, but I think its air flow meter related.

jib

 

[type49]

Just re read your description. If your "stutter" is just engine "missing" or flat, without any noise, then forget my answer. The cam adjuster makes an obvious buzz noise at about 1500-2000 RPM. The earlier superchargers do cut in at about 1300RPM & are similar to the air con clutch cutting in/out.

 

[jibcl500]

Yes its like it has a misfire and there is a noise like the AC clutch kicking in etc which is why I assumed it was the compressor. Without the MAF connected its fine.

jib

 

[jimsinessex]

Checking the kompressor cut in by revving the engine in neutral or park is very misleading. I checked mine this way by lifting the bonnet and raising the fly-by-wire throttle by hand and the compressor clutch would engage at about 1500 to 2000 revs as quoted above.
However as the car got more miles on it and the clutch mechanism wore a bit the cut in became just audible as a sharp click when inching along in traffic and was in fact engaging at 800 revs every time. I can only assume the engine ECU takes the load on the engine into account and engages earlier in gear. The ECU would detect load by comparing revs against fuel/air flow or throttle position.

My car is a 1999 W208 CLK 230K, later cars, of course, don't have a clutch.

Jim

 

[jibcl500]

Well it is the compressor cutting in, I increased the revs from the engine bay and watched the clutch connect and it seems that the compressor when running is quite loud almost like a bearing noise similar to the noise alternator bearings make when failed.

Me thinks the compressor is on its way out!!!!! I did notice recently that the car seemed to be quick to 100mph and then 100-120 was very flat and it took a long time to get the extra 20mph. (the speeds above where done on a private airstrip and not on public roads!!)


jib