603 Air Recirculation Valve (ARV)
 

Does anyone know if there is a rebuild kit available for the ARV on an '87 300D? Mine will not hold vacuum. I removed the cover and found that the diaphram has ruptured. I haven't removed the diaphram, so I'm not sure what is supposed to be happening behind it.

The ARV is isolated from the vacuum source and the vacuum port is capped, but I'm wondering if the ruptured diaphram can have a negative effect on engine performance.

Thanks,

EWS

Unless you're preparing your car for a concours event, you're better off with a disabled ARV.

In my case I plugged the port between the ARV and turbine outlet when I discovered a ruptured ARV diaphragm.

Sixto
91 300SE
87 300SDL
83 300SD

EWS,

Disconnect and plug BOTH the ARV and EGR valves. You will be rewarded with increased power, better MPG, and less sooty crap in the intake manifold. Here's some photos of the lines plugged and solenoids removed:

http://www.meimann.com/images/mercedes/W124_stuff/smog_solenoids.jpg
http://www.meimann.com/images/mercedes/W124_stuff/smog_lines_plugged.jpg
http://www.meimann.com/images/mercedes/W124_stuff/2_port_vac_fitting.jpg



And here are some shots of how EGR plugs up your intake:
http://www.meimann.com/images/mercedes/OM603_intake/pipe_before.jpg
http://www.meimann.com/images/mercedes/OM603_intake/pipe_after.jpg


Side note: The ARV existed only to assist the operation of the trap oxidizer. The trap should be removed on your car under recall, therefore the ARV is not needed at all. If you still have the trap, boogie on down to your dealer and get it removed for free, along with a new exhaust system - front to back - totally free! What a deal! :D :D



Regards,

sixto,

How did you plug the port between the ARV and turbine outlet?

The TO is gone and the EGR and ARV are disconnected and plugged.

Thanks,

EWS

You can test if it's leaking with a stopwatch. :) If your car's 0-60 time is near factory spec, it's probably fine. Also you could connect a boost gauge & see what your boost is like at WOT. Again, if the ARV were leaking, boost would be low (and power would be as well).

That said, I have heard of people opening up the ARV and adding a shim under the spring to make it stiffer, and press the valve shut tighter. Not sure if this applies to both KKK and Garrett turbos, but if you're worried about it give it a try. I never tested my ARV's for leakage, I just blocked them off. Oh, and I also removed the EGR completely (for off road purposes only, of course.) Here's a photo:

http://www.meimann.com/images/mercedes/OM603_intake/EGR_removed.jpg



Regards,

Now that I think about it maybe the diaphragm was okay and it was the piston that was shot. Looked like it pressed against the port at an angle and got deformed.

Anyway, I got a 13mm freeze plug from NAPA, pounded it into the port and threw in some JB Weld for good measure. Worst case if it comes loose is that it'll blow into the ARV cavity and stay there.

I did this with the turbo off the engine. I don't know what access there is with the turbo in the car but if you can get to the diaphragm, it shouldn't be a problem.

I was considered a threaded plug but I didn't want to risk cracking the the compressor housing.

Sixto
91 300SE
87 300SDL
83 300SD