91180

*** Issue has been found, It’s the AC compressor pulley/clutch


Just got the wagon buttoned up after replacing all the pulleys and tensioners and water pump on the front of the engine as well as the power steering pump and the car is still making the whining noise that I had originally replaced all that stuff for.

The noise the car is making is exactly like that of the oil pump on start up, but the issue is that it isn't going away once the car is warmed up. The noise gets louder as you rev the motor in gear when driving and in neutral. I really do not want to even think about replacing the oil pump, which is why I'm posting here hoping someone has had a similar issue that they fixed relatively easy. Any ideas?

kevm14

Might be worth an oil pressure check. Hot, cold, idle, high rpm. If everything looks good, maybe ignore. Only thing I'd be worried about is a damaged O-ring causing partial starvation and aeration of the oil (possibly leading to more noise).

91180

I will run the car with the belts off tomorrow and fingers crossed it doesn't make a peep. Hoping that its maybe the ac compressor

91180

This is the noise my car is making

Sulaco

Probably not related but mine was making a weird whine noise with engine revs that also didn't go away with heat. Ended up being low trans fluid.

91180

I did drop the valve body and replaced the conductor plate. Was making the noise before though. Trans fluid is where it needs to be.

obiwantoby

Sounds pretty normal to me.

91180

I don’t think that’s normal. The other e55’s that I have stop making the noise shortly after startup. It persists on wagon.

obiwantoby

Mine persists until a certain RPM. It is a peculiar noisy engine.

91180

Lol you sound like the guy that sold me the car😂

Sulaco

Oil pressure test is the only thing I can say might be helpful. But even then if if your oil pump pater dies, not helpful. Tough spot, sorry mate

91180

Well, I’m hoping it’s the AC compressor. Fingers crossed for tomorrow when I remove those belts!

M5 LOL

that is normal. the oil pump uses straight cut gears and they get nosey at times. My 2006 was louder than my 2005 is. There is a 46k mile difference between my current and my last one. I switched to 5w40 and the noise got a little quieter. Don't loose sleep over it.

obiwantoby

I'm still on the normal train too. But if he does the oil pressure test that will give an ease of mind. The first full minute here, you can hear th whine.

radride

I have a 2005 E55 Wagon as well and I have the same noise that never goes away. The mechanic thinks its the power steering pump but nothing comes up in the star scan as a issue in the car.

R.K.

obiwantoby

Just perform the oil pressure check. The oil pump does have to fill that front sump - but even after that seems loud. Bearing sound, power steering whine, straight cut oil pump gear all sound similar I suppose. I've attached the oil check procedure.

SICAMG

Normal for most if it's the pump. Do some search's, plenty of information.

nd-photo.nl

Wait a minute, if there is an actual service port for it, you can also use it to hook up a oil pressure gauge?

SICAMG

Yes. I actually tapped into the oil filter housing and have a oil pressure switch wired to an led light hidden in the left ac vent.
These cars have no oil warning system but really when has a Mercedes oil pump ever failed ?

nd-photo.nl

Not the oil pump, but the rubber seal can deteriorate/fail. I think we've all seen this video

radride

Here is what mine sounds like.

R.K.

91180

Took the belts off today. The car was much quieter after removing them. It’s in fact the AC compressor. Thanks to everyone that contributed. the video link I posted above is exactly what the car is sounding like, so if your car is making a similar noise after being warmed up, the AC compressor pulley/clutch is a likely culprit.

I just ordered Denso 471-1474 off Amazon for $290. Hopefully the wagon will be turn key ready for an epic road trip in the next few days.

kevm14

I had a whine on my S550 that conventional wisdom said must be a power steering pump. On recommendation from others, I replaced all tensioners and belt. Same noise. Finally someone said these A/C pulley bearings are known issues, and sent a MB bulletin that essentially walks through some of the common issues. I ordered a short belt to isolate the A/C compressor and bam, that was it. New pulley from eBay and I was back in business.

nd-photo.nl

Is the AC pulley easy to replace?

kevm14

It was on my S550 but no clue about the E55. On the S550 there is no clutch; it's a variable displacement pump.

All I was saying was it turns out that is a common source of issues on M273s, and I was happy it was relatively cheap and easy to repair. Curious if someone knows more about the E55.