W208 230k Supercharger Issue

[adambear]

Hi guys, ive had my newest clk for about a week ago now, its my second one now, my old one was a tin top. I just assumed the convertible was a bit heavier and was a bit slower but I have gone under the bonnet today and reved the car up and the clutch on the supercharger only just engages at high engine speeds. I thought it was a quiet supercharger lol compared to the old one but this now explains it. Any ideas what to test and how to fix? Many thanks in advance.

 

[John Jones Jr]

A common fault on the W208 & R170's is the K40 replay module, which if faulty can affect the S/c clutch engagement. Not saying this is the case with your car but very possible. Before throwing any parts at the car I'd get the car plugged into Star first. Maybe they'll be no codes but the Live Data might suggest what's at fault.

 

[adambear]

Thanks for your reply, do you know where is a a good place to plug in in essex? My mate has a code reader but am I right in saying the mercs have a different shape port to the normal odb ports?

 

[John Jones Jr]

Sorry can't advise but have a look here: Mercedes specialists across the UK - MBClub UK - Bringing together Mercedes Enthusiasts

 

[adambear]

Thanks so much

 

[streethawk]

Hi guys, ive had my newest clk for about a week ago now, its my second one now, my old one was a tin top. I just assumed the convertible was a bit heavier and was a bit slower but I have gone under the bonnet today and reved the car up and the clutch on the supercharger only just engages at high engine speeds. I thought it was a quiet supercharger lol compared to the old one but this now explains it. Any ideas what to test and how to fix? Many thanks in advance.

Hi it should engage at around 1500rpm so somethings not right + 1 for star also sounds as if the bypass valve is playing up. Does it run fine apart for the clutch engagement? Could be the maf as this makes alsorts of problems.

 

[flango]

Find someone who has snap on pro diagnostics much easier to find the fault with this as you can look at all the live data easier than with Star many people have star but don't know how to use it, things to check

K40 relay
Air bypass flap
Cam sensor magnet
MAF
Air piping
ECU for signs of oil

Sent from my iPhone using MBClub UK

 

[adambear]

The car runs great, you wouldnt think there was an issue if didnt know it was supercharged, the s/c cluch doesnt engage at any rpm, its not seized either as you can spin it by hand easily. I had a look online at the normal k40 issues and took mine out to look, it doesnt have any burning around any of the solder joints. It all looks brand new to he honest. Looks like ill have to bite the bullet and get it plugged in lol.

 

[John Jones Jr]

Have a look at this forum (R170), plenty of info on the M111 Kompressor's including non engagement of S/c.

R170 SLK Class - Mercedes-Benz Forum

 

[adambear]

Thanks I will have a look, I think they have their differences though, When I took out what I thought was my k40 relay box its very different to the ones on the SLK, or is it fitted in a different place.

 

[adambear]

Is this the k40 relay in the clk?

 

[adambear]

from looking up on the forums this is the sort of k40 relay I should be looking out for but its not in the same place as the slk so not sure if the above is the clk version?

 

[John Jones Jr]

Don't know which is which for your car, the first photo looks like an early K40 & the second a K40/4? Wouldn't get too hung up about it as there's other items that need to be checked as already mentioned by Flango.

 

[adambear]

Ok the k40 shows no sigh of burned solder
I am unsure how to test the air bypass valve
As for the cam sensor,if this had failed would to car even run?
The maf is clean other than that I cant test further
There is no damage to the air piping I cant find any leaks
And the the ecu is clean no sighns of oil.

 

[John Jones Jr]

The air bypass valve from what I recall won't operate if the S/c clutch is not engaging. As for the Cam sensor I can only speak from experience on the C230K, mine was faulty but the engine still ran.

Another possible fault is the ECU, it's been known for a Mosfet to blow, causing the exact issue you are having.

Supercharger fixed for £4.99 ! - Mercedes-Benz Forum

https://www.youtube.com/watch?v=nCmF6fK-Mn8

 

[adambear]

Oh really that's interesting, if the cam sensor is a fault its nice and easy and cheap to change I saw that about the mosfet but a bit worried about doing it lol. Its a shame the ecu's aren't easily interchangeable as these too are not that expensive.

 

[streethawk]

Ok the k40 shows no sigh of burned solder
I am unsure how to test the air bypass valve
As for the cam sensor,if this had failed would to car even run?
The maf is clean other than that I cant test further
There is no damage to the air piping I cant find any leaks
And the the ecu is clean no sighns of oil.

My old maf was dead and car ran rubbish like on 2 cylinders. New one sorted it and new breathers and a whole intake clean out ie intercooler and pipes etc to remove oil residue. Only thing I didn't clean was s/c which must of still had oil residue in which contaminated new maf after a year. Ran fine until I ha e it some hammer and the supercharger would then bomb out and not engage. Put it on star which said bypass air flap! It wasn't it was dirty maf. As it was only a year old I thought id clean it which everyone says don't do, but it's been another year on now and still fine. Just a thought have you checked s/c clutch magnet electric feed? Under the front plastic cover at front of engine where end of the cams are there is a plug left-hand side with 2 wires going in each end, you never know it could of vibrated undone or got some oil in it so clean with contact cleaner. You could also energize mag while engine off just to see if you can hear it click.

 

[adambear]

Here is where it gets weird, I took out a multimeter to see if the voltage from the cam sensor was changing with the engine speed, the car runs better with the cam sensor so you right John. The car has a bit of a rough clicky noise coming from the cam when you rev it up, this goes when you disconnect the cam sensor so there prob is a fault. But whats weirder is I checked the connection plug to the supercharger and the 2 wires that feed it have a permanent 12-14 volts to it so would this mean the clutch should be engaging all of the time?

 

[John Jones Jr]

But whats weirder is I checked the connection plug to the supercharger and the 2 wires that feed it have a permanent 12-14 volts to it so would this mean the clutch should be engaging all of the time?

It's the ground that's switched if I'm not mistaken.



Function: The electromagnetic clutch is activated by
means of a GND signal supplied by the engine
control module. The voltage is supplied either
by the relay module or the fuse and relay
module, respectively.
When current flows through the magnetic coil,
the gap between armature and rotor is closed.
Belt pulley and compressor are positively
connected by means of friction surfaces

 

[streethawk]

Here is where it gets weird, I took out a multimeter to see if the voltage from the cam sensor was changing with the engine speed, the car runs better with the cam sensor so you right John. The car has a bit of a rough clicky noise coming from the cam when you rev it up, this goes when you disconnect the cam sensor so there prob is a fault. But whats weirder is I checked the connection plug to the supercharger and the 2 wires that feed it have a permanent 12-14 volts to it so would this mean the clutch should be engaging all of the time?

When you say cam sensor do you mean the magnet on the end of the inlet side cam? If so it does click when revved iirc as it moves a pin inside the end of the cam to change the timing. On the later kompressor engines you have a sensor in the side of the rocker cover also but not on mine! Well not found one anyway and mines a 99.