I've read a lot of posts and threads and have seen the ARV mentioned quite a bit. So far I've gathered that 1. A lot of people remove or disable it and 2. it is the Air Recirculation Valve.
I haven't been able to figure out if it pertains only to turbos or not or to where it recirculates air and from what source. I'm not sure what benefits there are to removing it. Can anyone give me a rundown?
Do the '82 240D's have them?
Thanks

P.S. this is my first post

if you have an un-modded, American 240d.... you do not need to worry about this device.

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others in my family have the 300D turbos in the same year range (81-83) and I was just wondering for education sake, what the ARV is for and what it does?

Yes it is Air Recirculation Valve. Only on CA emission and '85 MY 617s. Cannot recall what 603s had them, all '87s had it and I believe all '86s.

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

Disable that POS and or remove the lines unless you have inspections. It is there to supplement the EGR.

The ARV lets pressure from the intake manifold escape back to the inlet, allowing the EGR to pass more exhaust gas into the intake manifold. This makes a really beautiful black goo stick to the insides of the intake manifold. It is fun to clean out too.... Ask anyone that has cleaned one.

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AJ

1985 300D (SOLD)

I'm not sure you can peg this as an egr improvement device.

It was only installed on models with trap cats... leaving one to believe it was installed for that application. It may be there to increase the exhaust flow though them so they heat up and burn off their collected deposits before they clog up... as they were designed to do.

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You need to elaborate on that as my car is not set up with a trap cat (never was) and has this device. I have seen several other 85's down here with it and no trap cat.

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AJ

1985 300D (SOLD)

do they have the california manifolds and air cleaner system?

edit* I feel like I'v made this mistake before. All '85 617s had this on the turbo, is that the assumption?

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I have the regular air cleaner and manifolds. Mine is a Fed. The others I have seen (neighbors car and cars at the GTG) were Fed.'s too. I have never actually seen a Cali. trap ox setup yet. I plan to get a picture when I do.

EDIT: I think the manifolds are different on the trap ox. setup. The turbo is mounted higher right?

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AJ

1985 300D (SOLD)

Yes the '85 Federal is the '84 CA and other previous. My car is odd as uses '84 MY parts but has MY of '85 built in October, 1984. huh.

Jeremy something or the other on here converted a true CA '85 to a Fed, he took pics and such if you are curious.

Either way it is not needed, remove it/plug it if you have to deal with visual inspections on Diesel. Or simply convert the car to earlier Federal bits and off you go.

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

yes, different manifold, and the turbo sits higher. Feel free to look at mine at the GTG, if you go.

Mine has the ARV and it was disabled when I removed the EGR. I put a vacuum cap on the inlet to keep crap out.

Pierre had some theory about the ARV helping the turbo spool or some such nonsense...I think it's there to assist in EGR.

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1985 300D cali 190K

http://mercedes.thatchermathias.com/mw300d.jpg

That is what I thought... Matthew, I missed looking at your engine with the hood open. Yea... I would like to get a pic of that trap ox and your headlights again (can't find the head light pics). I would really love to get rid of these DOT "death trap lights".

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AJ

1985 300D (SOLD)

ok.

we may never know the precise reason why MB put this on there. But it will, in fact, do all of those things mentioned.

heat up the trap

increase egr flow

spool the turbo quicker w/o building boost
^this also effects shifting / timing of shifts

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Interesting. I have an 85 SD federal. I plugged the ARV when I plugged the EGR. I am interested to see if I notice a difference in performance/shifting if I reconnect the ARV.

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1985 300SD 99K

I actually did the BB trick before I removed all of my "spaghetti". First I did the BB in the EGR and then the ARV. No difference... Then I removed all the associated plumbing, capped off the ARV and blocked the EGR. The difference in performance was amazing (in my case).

If you have over 100,000 and all of this crap is still hooked up. It may be a good idea to pull and clean the intake. FYI... It will probably be a mess.

Not to lose track of the original topic of this thread... I think we have covered it.

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AJ

1985 300D (SOLD)