'97 E320 W210 EGR shutoff valve on startup - PeachParts Mercedes-Benz Forum

junkmale · #1 11-04-2008, 02:28 PM

On first (cold) start I get a very high pitched buzz or whine that seems to be coming from the EGR shutoff valve on my 1997 E320. Although it could be coming from another location, it's loudest on the valve (listening through a stethoscope). The part number stamped on the valve is A002 140 25 60.

The buzz lasts for about 60-70 seconds, then the engine goes into a normal idle and everything sounds and runs fine. There is no check engine light, and the engine runs and idles smoothly when warm.

The buzz can sometimes be loud (maybe a ripped diaphragm/vacuum vibration type noise--if that makes sense?).

I'm wondering if this is an issue anyone has come across before, and if there is anything a DIYer can service/rebuild in respects to the valve. The new part lists for $404 (and I'm not inclined to shotgun parts at the issue until I can figure out what the latent problem is).

Thanks for any info.

Arthur Dalton · #2 11-04-2008, 03:15 PM

Pull a hand vac on it and see if it holds vac.

ILUVMILS · #3 11-04-2008, 07:32 PM

It goes away after 60-70 seconds? It sounds to me like it's the Air Injection pump running through it's normal cold-start cycle. Try pulling the fuse for the pump and see if the noise goes away.

junkmale · #4 11-04-2008, 10:59 PM

Okay, I'll look for the fuse and pull it to see. If you have a location/number I'd appreciate it.

The noise is not normal; is the sound I described consistent with the air injection pump failing? Does this pump shut off after the cold-start cycle is complete?

junkmale · #5 11-08-2008, 08:44 PM

Thanks to ILUVMILS, I was put on the correct track. It is indeed the Air Injection pump. I put the car on ramps, did a cold start and was able to pinpoint where the sound was coming from. So now (knowing the price of a new pump) is there anything serviceable, or do I need to get a whole rebuilt unit. It sounds like the bearings are going out. Should I wait till it fails catastrophically and throws a code, or should I be proactive?

TIA.

ILUVMILS · #6 11-08-2008, 09:25 PM

I think that once you find out how much a new pump costs, your question will answer itself!!!

suginami · #7 11-09-2008, 04:07 PM

The dealer does sell a rebuilt kit with the pulley.

ILUVMILS · #8 11-09-2008, 06:53 PM

Junkmale's car has an electric air pump. About $750 from AllPartsExpress.

junkmale · #9 11-10-2008, 11:26 AM

I know the the air pump is pricey, but the sound it makes is pretty horrible. Is it normal for the pump to cycle on after the car is warmed up? I never was able to determine the correct fuse for the pump; do you have any idea?

Is it fairly easy to get to all the bolts when the car is on a ramp to pop a new one in? (no special tools needed)?

TIA.

junkmale · #10 11-11-2008, 11:38 PM

I'll answer my own question here. I put the car back up on the ramps, pulled off the underside plastic covers (2), and access to the air injector is ample. One bolt, one hose, and one electrical connector, and the entire unit slides out of a rubber mount.

I pulled off the end cover (3 torx screws) and had access to the bearing side of the shaft. It seemed to turn pretty easily, but felt like it was dragging. I'm sure the loud buzzing sound would be fixed with new bearings, but alas, I don't think a rebuild kit is available.

So it looks like a new unit is in order. Thanks for all your input.