For those who think the whine upon cold start up is you air injection pump.
At the beginning the noise was REALLY loud and it was coming directly from the oil pan (the car was on a lift). You could feel the vibrations in the oil pan. This was at idle. After increasing a little the engine speed the noise suddenly became much lower (?).
I let the oil temperature reach 80°C, stopped the engine end read the oil level from the dash, so I added oil until the level was ok.
Result: with Mobil 1 0W40 the engine is quiter (related to the oil pump noise) but the whine is not completely gone. Is it the viscosity? Some additive?
What could it be? I have the impression that some shockwave produced in the pump is hitting the oil pan that acts as a loudspeaker. The pick up pipe is going just straight to the oil pan. Is it possible?
it's just a plain 55 
I went to 2 MB garages, one in Switzerland and one in Germany (I leave close to the border).
In Switzerland they told me they already changed the oil pump in 3 different cars without success and without really understanding where the noise is coming from.
In Germany they told me that if you fill something different than Mobil 1 something changes. They can't explain what is different and they did even open an engine to see if the parts were out of spec or worn. Nothing, absolutely nothing. They just know it can be oil related but nothing more. Otherwise, as you say, they say it can happen and it's normal.
Still don't like the noise...
it's just a plain 55 
I went to 2 MB garages, one in Switzerland and one in Germany (I leave close to the border).
In Switzerland they told me they already changed the oil pump in 3 different cars without success and without really understanding where the noise is coming from.
In Germany they told me that if you fill something different than Mobil 1 something changes. They can't explain what is different and they did even open an engine to see if the parts were out of spec or worn. Nothing, absolutely nothing. They just know it can be oil related but nothing more. Otherwise, as you say, they say it can happen and it's normal.
Still don't like the noise...
That noise we are hearing is engine oil pump noise (in 99% of 55k cars, especialy W211, which opil pump have 6 internal gears (compared to only 2 gears in all other 55k engine oil pumps). Also that engine oil pump noise heavily depends on oil viscosity we are using (and milage on that OCI).
After A LOT od researching on my engine, i have discovered that with German Castrol SLX Professional 0W-30 (in working temp it acts more like 0W-40) after cca 3000 km the noise goes down completely. Cold and hot engine.
Also, I have had my car make the noise a second time after some idling and driving a short distance to pull out of my parking garage at work. Idle's 3-4 min, drove a couple hundred feet and as I opened my window to put the key card in to open the gate so I can leave I heard it kick back in for a bit then wind down again.
It's not the oil pump unless there's an electric motor on it for extra cold start oiling or something silly.
Last edited by BBBSS; May 11, 2012 at 02:47 AM.
Also, I have had my car make the noise a second time after some idling and driving a short distance to pull out of my parking garage at work. Idle's 3-4 min, drove a couple hundred feet and as I opened my window to put the key card in to open the gate so I can leave I heard it kick back in for a bit then wind down again.
It's not the oil pump unless there's an electric motor on it for extra cold start oiling or something silly.
With that said, Snogard has always said it's the oil pump, and he may be right, however my mothers C240 ( 2.6L V6 ) does the same noise. So does a co-workers E500. Those do not have the upgraded oil pump yet they whine just the same on cold start up.
I also hear it a LOT louder in the transmission bell housing than I do where the oil pump is. And it just so happens that the 722 tranny uses a gear pump for the transmission which is unconventional, and tend to be whiny, since most auto transmissions use vane pumps which tend to be quiet.
Unless something is being drained and then filled up quickly which would make sense to me.
When I rebuilt my trans, no difference in noise whatsoever even though my original trans pump was shot it still made the same sound.
Last edited by pearlpower; May 12, 2012 at 04:30 AM.
The Best of Mercedes & AMG
That noise we are hearing is engine oil pump noise (in 99% of 55k cars, especialy W211, which opil pump have 6 internal gears (compared to only 2 gears in all other 55k engine oil pumps). Also that engine oil pump noise heavily depends on oil viscosity we are using (and milage on that OCI).
After A LOT od researching on my engine, i have discovered that with German Castrol SLX Professional 0W-30 (in working temp it acts more like 0W-40) after cca 3000 km the noise goes down completely. Cold and hot engine.
Can't tell if it was SLX but is was synthetic for sure. As I live in Switzerland we don't make a difference between German or other sources. But it may be what you're talking about.
After 2 weeks I filled Mobil 1 0W40 and the noise became less loud, but it's not gone away completely.
It is the oil pump for sure: I started the engine while on the lift and the noise was coming from a precise spot: the front part of the oil pan. I also checked other components as tranny and accessories: everything is quite.
Gear pumps aren't new to me as I install them in the company I work for (as for metering or transferring viscous liquids). When they are noisy sometime it helps to install a compensator, a pulsation damper.
Has anybody already tried something like that in those engines?
It shouldn't be complicated as around the oil filter housing there are several connector that can be used.
Stefano
Is that some kind of EGR or is it part of the air injection system?
The passages look as if they wrap around the nose like it is an air pump built into the nose of the drive.
What is all of that for?
G
Is that some kind of EGR or is it part of the air injection system?
The passages look as if they wrap around the nose like it is an air pump built into the nose of the drive.
What is all of that for?
G
Sure sounds like an electric motor to me. Gonna try to make a youtube video of it.
Very loud compared to everything else going on when I start my car. Sounds just like an electric motor starting up and slowing down when it turns off.
Now if I could just figure out why the radio won't hold the station when I turn the car off and the navigation shows me 50 miles away. Just changed the auxiliary battery btw and no improvement.
https://mbworld.org/forums/w211-amg/...rough-sds.html




