williamk123

Hey guys,
I have a 2001 ML320 that has been progressively getting worse. It started about a month ago with it sounding a little out of tune but now it shudders to the point where I don't even want to take it out of the garage. The spark plugs have been replaced and being that it's progressive I assume that it's not the coils as they work or they don't with nothing in between. Any thoughts?

01ml320benzito

Do you have any codes? CEL?

Maj. Dundee

You might have a broken vacuum hose. With the use of a mirror, check all the hoses at the rear of the engine.

Jerry Easley

(Applies to any 112 series engine)

A decade+ later this advice gave focus to solving the same problem.

After swapping in a low-mileage engine w/all new hoses (water and vacuum), had same thing happening. Misfires P0300, Lean Mixture P0171, P0106 MAP Range were significant codes along w P0131 02Sensor Low Voltage. Was intermittent intensity but always present.

Found it at brake booster port. (Fog of carb cleaner used to locate leak source)

Cheap and easy repair by replacing the o-ring inside. Requires 3 pieces after pulling the booster line out of the way. My old iPhone5 (small form-factor) was used to take first photos of port.

PROCEDURE: (Clear space to work as needed.) Remove existing Cap by hooking, then pulling outward and breaking the tabs which are otherwise squeezed inward together to release hose. The retainer can be pulled out w/a small hooked tool. As well as the old O-ring. Remove the last two carefully so no small pieces are left inside.

Install new O-ring and Clamp Ring by sliding into booster line end then guiding into position. Retract line carefully. Connector Cap just snaps in place.

First one “took a minute”. I could do another in 10-15 minutes after lifting the hood.

the 3 parts cost ~$20 from MBParts. Brake Pressure Connector Cap 111-141-00-81. Clamp Ring 111-141-02-42. Seal Ring 111-997-05-45.


O-ring removed

O-Ring in place