Intermittent kompressor, advice please.

[BigDusty]

from the description you might have disconnected the mass airflow sensor.

Definitely no, cross my heart or are you saying it may some how be linked with the MAS?

Actually, I have this part in front of me as I type, wanted to get the part number from it. Going to put it back in a minute and go for speedy spin.

BigD

 

[GrahamC230K]

Here we go, is this it? - I meant MAS not Mass BTW!

 

[BigDusty]

Here we go, is this it? - I meant MAS not Mass BTW!

QUOTE]

Sorry, no, that's the Air Mass Sensor.

The part I'm talking about is located under the Brake ABS Unit next to the alarm\immobilizer (on my car anyway). It has two 1/2" rubber pipes connected to it and a two pin plug for the electrics. It has a lump of rubber around it's waist to hook onto a flat metal hook welded or bolted to the inside wing.

Wish I could find my camera!!

BigD

 

[GrahamC230K]

Doh! Thought we had it. I know it's the MAS, just thought for a minute you didn't! Nevermind, I'm really intrigued now.

 

[BigDusty]

Doh! Thought we had it. I know it's the MAS, just thought for a minute you didn't! Nevermind, I'm really intrigued now.

Got some photos, first one ok.

Second photo a bit blurred, not my camera but better than a poke in the eye!

BigD.

 

[BigDusty]

Doh! Thought we had it. I know it's the MAS, just thought for a minute you didn't! Nevermind, I'm really intrigued now.

Sorry. hate to teach Grandmas to suck eggs

 

[GrahamC230K]

I found a use for my 2,000,000 candle power torch and had a look at that part. Mine is identical to yours (surprise!). Is your car a prefaceleift or do you have an aftermarket alarm?

Anyway, I am absolutley none the wiser as to what it is and couldn't have got a more benficial photo.

I was interested to see if mine suspiciously looked clean and new, but it's as dirty as everything else that hasn't been replaced!

Maybe a PM to Dieselman to see if he can identify the part?

 

[BigDusty]

I found a use for my 2,000,000 candle power torch and had a look at that part. Mine is identical to yours (surprise!). Is your car a prefaceleift or do you have an aftermarket alarm?

Anyway, I am absolutely none the wiser as to what it is and couldn't have got a more beneficial photo.

I was interested to see if mine suspiciously looked clean and new, but it's as dirty as everything else that hasn't been replaced!

Maybe a PM to Dieselman to see if he can identify the part?

Only had this car for a month so I don't know it's history and the previous owner bought it when three years old so I wouldn't know what's original or aftermarket.

I have asked MB to look this part up via the part number and I'm still waiting to hear from them with great anticipation. They said they were very busy today so I might not hear from them until next week

The tapping noise this thing was making when my Kompressor stopped working was quite loud, but after cleaning off the corrosion is now working fine but how it affects the running of the car and the Kompressor is a mystery.

That area of the car was very grubby and as you can see by the photos there is a bit of corrosion just above it (which I have now covered with grease). No doubt the connection on this thing must get some punishment so a bit of grease or oil will help to avoid future headaches.

Have you tried to disconnect yours and if yes what condition was it in?

BigD

 

[Bazzle]

Head light washer pump.

Bazzle

 

[GrahamC230K]

Head light washer pump.

Bazzle

No!

 

[BigDusty]

Head light washer pump.

Bazzle

If it is, then I'm in trouble.

A tad bored tonight so decided to rummage around under my bonnet to see where the two pipes lead too (neighbours must think I'm nuts).

The one pipe definitely goes to the throttle body, (so I really hope there is no water going through this ) how do I know this? Because I blew through one end of the pipe and my champagne alcoholic breath came out the other (actually it was cold beer but still tastes good).

The other pipe leads to the rear of the car but mad as I might be was not going to clamber under the car in the dark specially as it has been raining to find out where it finishes. I'll stick it on the ramp tomorrow and have a look.

[/IMG]

So, this part obviously plays an important role but what, we have yet to find out.

BigD

 

[nigel cross]

Has anybody got a copy of EPC to assist the tracing of the parts described?

 

[s1gar]

it may not help but read this......this is excatly what my car is like. just found it
http://www.mbclub.co.uk/forums/showthread.php?t=11796&page=1&pp=15&highlight=kompressor

 

[Dieselman]

The part looks like a purge valve that is electrically operated.
It is allowing air and petrol fumes into the inlet manifold at high vacuum conditions.
The reason why the engine runs so badly when the pipe is disconnected is that you then have an unregulated air leak so the mixture goes lean and the idle tries to rise.

It sounds like a possible theory fo rthe compressor issue, however there is no feedback from the valve to the ECU so it wouldn't know if the valve was working, other than the MAF might pick up hte airflow into the manifold.

I can't understand why MB don't grease the electrical connections, it really does stop corrosion and poor electrical contacts.

 

[benzonline]

I had this problem a few months ago with my C230K...same engine.

However, the kompressor ALWAYS engaged when revving the engine at a standstill. But when using the kickdown (such as going up a hill) it would simply rev (sometimes slam the gear) and not give any boost.

In the end it got worse enough to trigger the check engine light and the cause was the MAS sensor. Shifting and idling were otherwise normal...so be careful when you read symptoms of a failing MAS, they arent the same...the car never stalled for example.

Another thing I heard it could be a K40 relay located in the box where you check the codes. Look at all the circuits, open them and check for a burnt solder joint.

 

[BigDusty]

The part looks like a purge valve that is electrically operated.
It is allowing air and petrol fumes into the inlet manifold at high vacuum conditions.
The reason why the engine runs so badly when the pipe is disconnected is that you then have an unregulated air leak so the mixture goes lean and the idle tries to rise.

It sounds like a possible theory for the compressor issue, however there is no feedback from the valve to the ECU so it wouldn't know if the valve was working, other than the MAF might pick up the airflow into the manifold.

I can't understand why MB don't grease the electrical connections, it really does stop corrosion and poor electrical contacts.

Thanks Dieselman for the info. The ECU theory was only a wild guess but all these components however big or small play an important role to the cars smooth running and performance and it only takes one of them to develop a minor fault and have a knock on effect to upsetting the rest of the car, (pointing out the obvious here).

I have had and done quite a bit of work to the car over the last month, full service (by MB), new HT Leads, Air Mass Sensor, Air recirculation flap and more, and even though the car was running allot smoother it wasn't until I cleaned up the connections on this "purge Valve" that all problems have now been cured (touch wood) and the performance has noticeably improved.

I have been looking at all the other electrical connections and have checked them for corrosion and given each one a dab of grease. There are so many though, I'm sure I've missed some.

Until the next problem, which I'm sure won't be far away and thanks to all the help and advice, very much appreciated.

BigD

 

[Bazzle]

Head light washer pump.

Bazzle

I was wrong. Its the petrol tank purge valve.
I should of looked harder

Bazzle

 

[BigDusty]

MB has just got back to me (that was nice of them) and they call this part a regeneration valve. I've also looked in my Haynes manual (think I've found the correct part) and they call it a Purge Switchover valve and it leads to the Throttle body (idle speed control actuator). The other pipe leads to the Activated charcoal canister, that is then linked to the Fuel expansion reservoir and that is linked up with the Fuel Tank.

 

[s1gar]

what does it do?
and is your problem similar to the thread i put up on my last post??

 

[BigDusty]

what does it do?
and is your problem similar to the thread i put up on my last post??

Actually, I'm not sure what it does, still looking into it.

What I have learnt is that this valve doesn't have a direct affect with the kompressor but rather the emission side of things and because of this was somehow having a knock on effect with my car not performing as well as it should and causing the kompressor to fail.

MB informed me that this valve actually failing is very rare but with corroded connections would cause all manner of problems.

Because of this I am checking all electrical connections on sensors and valves etc for corrosion and greasing them to avoid further problems which I suppose everyone should do just for elimination purposes as it doesn't cost anything to do.

The other thing I have learnt is that when my kompressor failed the first conclusion you come to is "my kompressor or my air recirculation flap must be worn and needs to be fixed or replaced" but obviously in my case there was nothing wrong with them, they were just being affected by some other fault. I must say that my car has done just over 200k so I still replaced the ARF just in case.

Unfortunately this is no help to you because this means your problem could be something obvious like the Air Recirc Flap (if you have one) and with my car is one of the first things you suspect or it could be a faulty component which has absolutely nothing to do with the kompressor but is causing it to fail anyway.

It might of taken MB ages to find this problem because when I had my car fully serviced I informed them at the time there was a problem with the kompressor. They couldn't pinpoint the problem and there were no fault code readings either. What also made it difficult was my problem was intermittent so if it was happening all the time, might have been easier to trace.

Even though I've only had this car for a month, I am getting to know it well already. Every bump, rumble, rattle, squeak, ticking etc so I was lucky to find the fault with this valve because of the loud ticking coming from it.

I wish I could offer you better advice but what makes things awkward is that there are differences with our cars and I'm only just getting to understand how mine works. Talk about a crash course on Mercedes maintenance, my last car was a Vauxhall Cavalier and compared to this that car was a walk in the park when it came to repairs.

As to the other post, there are similarities with the performance problems but it looks like the cause is totally different to mine.

BigD