resonator flap cleaning OM606 - PeachParts Mercedes-Benz Forum

VW1300 · #1 07-30-2012, 09:46 PM

My P0200 code, which went away for a few weeks, is now back with a vengeance. My EGR seems to be working OK, so I want to test the flaps. Some questions:

1. If I pull on the flap vacuum line with a mityvac, how much vacuum should I need for it to open?

2. If I pull the crossover and the valve seems sticky, is it easy to remove the flap for cleaning? Just unbolt, clean, and lube? I couldn't find a past thread on this actual question.

3. The crossover pipe connects up to the manifold with 2 O-rings, correct?

All vac lines look like they're in good shape and I can't see any loose or missing lines. By the way, I checked mileage for first 2 fill-ups, I got 26 mpg, which is disappointing. Any advice on improving that is welcome too.

thanks,

Jeremy5848 · #2 07-30-2012, 11:09 PM

I don't remember how much vacuum it took last time I checked one of the flaps. Probably 10-15" Hg.

The flap comes out by removing two bolts (probably 10mm wrench). Then it's easy to take apart and clean. Soak it in diesel or (better) biodiesel. Note that with a functioning EGR the flaps will be black with an oil-soot goo.

The crossover indeed has an o-ring for each of the two pipes that go into the manifold, also two o-rings for the interconnection pipe at the EGR valve.

26 mpg is not terrible, both my cars average 26-27 mpg around town. If you take it out on the road and blow some of the soot out you should do better than 30 mpg. Disabling EGR may not help the fuel economy but it will keep the intakes a lot cleaner. My '96 was filthy after ~250,000 miles; the PO had to replace flaps at least once -- they were so gunked up they quit working.

Jeremy

VW1300 · #3 07-30-2012, 11:54 PM

Jeremy:

Thanks for your advice - are those O-rings re-usable, or do they need to be replaced every time? I asked Phil about the big O ring availability earlier this evening.

10-15" sounds reasonable to me for flap movement. Just for my own reference, what kind of vacuum should I have from the little hoses going to the flaps?

Thanks,

Jeremy5848 · #4 07-31-2012, 12:18 AM

Quote:

Originally Posted by VW1300

Jeremy:

Thanks for your advice - are those O-rings re-usable, or do they need to be replaced every time? I asked Phil about the big O ring availability earlier this evening.

10-15" sounds reasonable to me for flap movement. Just for my own reference, what kind of vacuum should I have from the little hoses going to the flaps?

Thanks,

The o-rings can be reused so long as they aren't damaged (cut/gouged) or rock-hard with heat and age. Put a little silicone grease on them.

I have no idea what the vacuum level is at the flaps -- probably system vacuum, which is about 20" Hg.

VW1300 · #5 03-07-2013, 09:54 PM

FOLLOW-UP: The P0200 code never went away. The flaps worked when vacuum was applied manually, but flaps were not opening and closing with engine running - conclusion, they weren't getting vacuum.

Last January I took it to K&H ******** in Houston - diagnosis was bad vacuum transducers. I don't recall what they charged me for the transducers, but in retrospect if they were suspect anyway, I should have probably replaced them and saved a bunch of $.

The car seems a little more responsive with the flaps working, and I wonder if a '96 I drove 2 years ago which was a total slug, had non-functioning flaps.

Jeremy5848 · #6 03-07-2013, 10:07 PM

Non-functioning flaps (meaning "closed all the time") will lock the engine in low-speed (below 2550 RPM) mode. The car should move out normally but gag at higher RPMs. Total slugness may be due to a dirty air filter, EGR soot clogged intakes, or an underperforming IP due to bad fuel.