OM606 Vacuum Pump - PeachParts Mercedes-Benz Forum

chazola · #1 10-25-2011, 04:57 AM

Hello, car is '94 E300D W124 wagon with 215,000 miles... I think my vacuum pump is starting to make noise- there's a random scratching noise that lasts less than a second every so often when the engine's running, listening with my advanced mechanic's stethoscope - a long screwdriver - it seems to come from the vacuum pump area. I'm not having any vacuum issues: brakes are normal, transmission shifts smoothly, and engine shuts off fine. I've not replaced one before- anything special I need to do removing and installing? cheers...

compress ignite · #2 10-25-2011, 05:33 AM

One time use only.

Hand Turning the Crank to move the "Ramps" so they aren't pressuring the V.P.
during re-installation will HELP.

CrissCross Torque the 6 Bolts (Just like you do a Wheel's Lug Bolts)

Communal Opinion is that the Torque Specs for the bolts should be 10Nm.

PeachParts Mercedes ShopForum - Search Results

Oh,Yeah...'Have you checked that all the "Walter Mitty" equipment involved
with the Serpentine Belt Drive Tensioner Apparatus: Springs, Pulleys,Bearings,
Etc. ARE NOT the Culprit(s)? [I.E. "Making the Noise"]

chazola · #3 10-25-2011, 05:53 AM

thanks CI, I'm pretty sure it's the pump, I took the belt off and spun all the pulleys and they all spin fine with no noise/resistance, the spring and shock on the tensioner are quite recent and the idler wheel is in good condition, spins freely with no wobble etc. I'm gonna have another listen today and see, with the screwdriver the 'scratch' sound seems most pronounced when it is against the vacuum pump housing and the fuel filter assembly above it. I may see if I can record it and stick a vid up on youtube in a bit...

chazola · #4 10-25-2011, 07:28 AM

here's a video, you'll probably need to turn it up a bit... can hear it at around 27, 35 secs in quite well and after....

Mercedes E300D W124 'scratching' noise - YouTube

Chris W. · #5 10-25-2011, 01:37 PM

Interesting noise. I can't imagine the vac pump making an intermittent noise like that, as it just pumping in and out while being driven by the timing device. I'm trying to think of anything which could be making that noise and I'm coming up dry.

If you replace the vac pump you are perhaps a bit early, but not too much, in other words even if you replace it and it doesn't fix the scratch, I think the consensus is that 250 - 275K is about the lifetime of a vac pump on a 606. So if you plan to keep the car it's money well spent.

Try opening the oil fill while idling and listening to the cam and valves...?

Rgds,
Chris W.
'95 E300D, 352K

Mad_Matt · #6 10-25-2011, 02:18 PM

Form reading the post I'm assuming you have a serpentine belt. If you're getting intermittent chirps/squeaks it's typically one of the pulleys. Does on of the pulleys attach to the same accessory bracket? If so I'd start there. I had a ghost of an issue like that on an my stroker and it ended up being the idler pulley by the second alternator. It passed the roll and wobble test by hand. I think the tensioner and the drag of the accessories can create more drag then you can by hand.

chazola · #7 10-26-2011, 02:20 PM

The power steering pump and tensioner/idler are closest to the vacuum pump, I think I'm going to replace the idler pulley as it's cheap and probably needs doing anyway, and see how that goes...

alipak · #8 10-26-2011, 06:53 PM

My Vac pump was making this noise before it failed; found out it had a worn timing gear where the pump sits on the block; I replaced both the timing gear & V. pump. No issues since then. I must add my car had about 220k mile then which is approx. the same mileage that you have now.

chazola · #9 10-27-2011, 09:04 AM

alipak- was changing the timing gear a difficult job?

alipak · #10 10-27-2011, 11:52 AM

Chazola
Yes it was hard to pull out the gear and the timing had to be reset.

Luckily my Russian friend knew how to or else I would had to take it to the shop.

WINGAS · #11 10-27-2011, 12:19 PM

Some of us are hoping to get lucky and not replace that gear. The VP failed on my '95 and it was a mess. Torched the motor, filled it with metal.

I already have one bought from my '96.

Don't fool around with these. Repalce it, or have it replaced if the gear looks anywhere near abnormal along the surface the roller rides on.

alipak · #12 11-01-2011, 10:57 AM

Chazola
Keep us posted what you find out on your Vac. pump/Timing gear; forum will learn out of it.

chazola · #13 11-02-2011, 09:20 AM

Will do. I've just sourced a replacement pump from a low-mileage car since a new one is £££'s, hopefully will get the chance to replace it in the next week or so. I'm hoping the timing gear is ok.

chazola · #14 02-06-2012, 11:37 AM

Just an update on this if anyone's interested- the 'swishing' sound went away and I didn't have any vacuum issues but a few weeks ago I got a much worse and noticeable (from outside the car) banging sound from the front of the engine. Screwdriver diagnosis confirmed it was definitely the vacuum pump so I decided time to take the old one off- the covers over the bearing races had popped off and were sitting by the channel for the timing chain, and the bearings themselves were stuck fast in the races with one about to make a bid for freedom but wedged in the track still. The cam on the IP timing gear had worn through the cam follower, luckily there seemed to be no damage to the IP cam surface.

This was a fairly easy job except some of the bolts for the pump are a pain in the arse to get to. As with almost every job on this engine everything is packed in tightly close together, you'll want to get under the car for the bottom bolts, makes things easier. I didn't need to take the fan off, just the fan shroud, and loosen the tensioner and move the belt out of the way to get access to all the bolts. My main connector for the brake booster vacuum line was rusted pretty well too which needed soaking before it would budge. Rotate the engine so the pump will go against a flat spot on the cam, then it screws back on easily.

I'd say anyone with a 606 if you hear any strange noises from this area take off your pump and check it, or think about just replacing it if you have over 200k.

pics of the old pump:

sixto · #15 02-06-2012, 01:32 PM

I'd like to see a picture of the IP timer. I can't see how it could survive with no vacuum pump follower left to speak of.

You mention a bearing cover. I haven't seen one. There is a cage that keeps the ball bearings spaced in the race. Once the cage goes, the bearing can come apart. This is an earlier stage of what's likely the failure you experienced. Same pump, bearings on opposite sides of the cam follower -

FWIW, US 606s switched to a rotary vacuum pump midway through the '97 model year.

Sixto
87 300D