I took my ML320 to a local parts store because it was idiling poorly. They checked the codes and a PO400 (egr flow) came up. I tried cleaning the tube that goes to the egr valve last night. The tube was not blocked and that didn't help. I also cleaned the maf sensor and put seafoam in the gas and that did not help either. What all is involved in replacing the egr valve? Does anyone have any other suggestions of things to try? Thanks!

Common problem on the M112/113 engines.

Takes a good dealer tech about 45 minutes to replace that valve & tube.
Just a matter of removing the air intake tubing & removing several bolts & the EGR pipe.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

What controls the actuator solenoid on the EGR valve? I have a code PO400 and yet the EGR passed on car test. Opens with -10 psi vacuum, solenoid when jumpered causes engine to choke down so exhaust gas is being fed into the intake (intake tube is clear of any carbon) rubber vacuum tubes all replaced on EGR valve. I suspect whatever controls the solenoid is not working.

Well, last night a buddy and I changed my EGR valve, cleaned the EGR tube, and replaced the gasket on the EGR valve on my 2000 ML320. We ended up dumping coolant all over the place moving the overflow reservoir so we could get to the back side of the engine. Once we put the new EGR valve on we had to run out and replace the coolant that I had dumped everywhere. We got back started up my truck, it started horribly then it just stalled. Checked over everything, found that the actual intake hose from the air filter wasn't seated properly. Re-seated it and tried again. This time the engine revved up to about 2-3k rpm, dropped back done gurgled a bit around .5k-1k then promptly died. I think that when my coolant poured out of the overflow tank, it got somewhere it shouldn't, everything appears to be where it is supposed to be, but the car won't start and stay on. I think that we have something where it shouldn't be, but I don't know what or where. Suggestions/recommendations are greatly appreciated. Thanks.

__________________
1993 300D 2.5 Turbo
Daily Driver.... 238,000 miles and counting (Gone for an '03 Camry)
2000 ML-320
New Daily Driver...139,xxx and still in one piece...

I put a screen door spring in a variable speed electric drill and honed out the tube. It worked fine afterwards. You must crawl into the engine compartment to get at it and be careful as that old plastic (1998) is getting brittle.