It runs inside the cabin and just ends under the dash; no filter or anything. I guess they figured the air in the cabin would be clean enough already.

For what it's worth, I removed the black box and all the extra unnecessary EGR related crap in the vacuum system a few months ago, no problems have cropped up. Much cleaner looking :-).

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'81 300TD Wagon 355k (Miss Diesel)
'83 300SD 180k
'84 500SEL 190k (Parting it out)

Andreas, thanks for the info. I am going to the same thing on the SD.

Just an update on the installation of the kits on the 617:

If you are finding any difficulty holding the copper plate on the exhaust pipe and tapping the plate with a ball peen hammer, one of the forum members has come up with this solution:

Remove the metal corrugated tube from the bottom of the EGR valve, after you have removed the EGR valve from the engine. The bottom of the EGR valve looks identical to the exhaust pipe. So, put the EGR valve in a vise, and tap the copper plate onto the bottom face of the EGR valve.

Return to the vehicle with the copper plate. Put some sealant onto the back of the copper plate, place it onto the exhaust pipe on the manifold, and install the clamp.

This approach is definitely easier on the back

Sorry to revive an old thread, but could you confirm something for me?

I'm having trouble following this. What year/model is this for? (I have an 83 300D-T and 84 300D-T (both Calif.)
Does this mean that both coolant sensor and the piggyback valve are entirely unnecessary without the egr? I wish there was a nice picture like the one posted by Dave M. Has anyone done something this to their 83 or 84 300D-T, and would like to post pictures for the benefit of others?

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J. S. Park

'82 240D Manual 240D (sold)
'83 300D-T 230k (sold)
'84 300D-T 118k (sold)

That is correct. Just be careful that the piggyback valve is only for the EGR. On some engines, there were two valves, and one controlled the EGR and the other was transmission vacuum related. It all depends on which vehicle you have. "Most vehicles" use those piggyback valves simply to regulate EGR.

Just track the hoses and see if they end up at the EGR valve. If so, then the piggyback valve is not required.

The kits instlalled very smoothly, thanks to Brian Carlton's detailed instructions.

However, I went on to remove what I thought were unnecessary vacuum lines, and I have two questions about what is actually necessary and unnecessary:

1. On my 1983 300D-T, I removed all the lines from the egr, all the way upstream to the black plastic box on top of the valve cover (I found no arv vacuum line). so far so good. However, in my zeal, I removed the plastic box "switchover valve" and contents as well. Now I'm realizing that I went too far--that one of the functions of the box is to allow a "bleeding" of vacuum depending on accelerator travel, thus reducing vacuum to the transmission when the accelerator pedal is pressed. So, I should put it back. Can someone please confirm this for me?

2. On my 1984 300D-T California (the system is different on it; see attached diagram), I did something similar: removed all lines from the egr and arv, including the "vacuum converter" (#84) on the passenger side wall of the engine compartment, just back of the headlights, and going all the way to the vacuum junctions at the driver's side of the engine compartment. Because there is no plastic "switchover valve" on top of the valve cover for this year/Cali model, I was assuming that on this car, I did not mess up--that the transmission-related-accelerator-vacuum-reducing function is somewhere else, and not integrated in the parts that I removed. (The trans. certainly feels okay). Is this correct? Or, did I mess up this one also--could it be that the "control unit" (#80), using the data from the "rpm sensor" (#82), actually uses the "vacuum converter" (#84) to do just that, i.e., reduce vacuum to the trans depending on accelerator pressure? Please don't tell me that I just answered my own question!

Any light you can throw on these questions will be much appreciated.

Attached Thumbnails

 

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J. S. Park

'82 240D Manual 240D (sold)
'83 300D-T 230k (sold)
'84 300D-T 118k (sold)

Those valves do send signals to the trransmission.
They are used to simulate the vacuum signal that a normally aspirated engine would get by sensing throttle position.
I would not recommend removing them.

Danny

__________________
1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination

The black covered valve on top of the camshaft cover of the later models like mine is not for shifting, when the valve is bad it will affect shifting though. It is either open or close, no type of a bleeder. From there the vacuum is sent to the EGR valve to open the valve up. If there are no leaks in this system there will be no effect on the transmission's shifting.

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Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

Well apparently on some cars it does effect the transmission and on some it doesn't.
I think people need to be aware of this before they start removing it.

Danny

__________________
1984 300SD Turbo Diesel 150,000 miles

OBK member #23

(\__/)
(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination

I have a question on this subject - mine is an 85 California 300TD. I have a micro switch on the valve cover. Does anybody know what this is? What does it control?

Thanks

Steve

We have had this discussion many times.

Some vehicles have the valves on the valve cover and they control both EGR and transmission vacuum. There must be two different valves for this to occur, AFAIK.

Some vehicles have a single valve on the valve cover that controls only the EGR.

You have to trace them down to see which function the valve controls. If it's EGR, the valve can be eliminated, if it's transmission vacuum, it cannot.

Brian

Thanks for the fast reply. But, I don't have any valves on the valve cover, only a single (small) switch, the kind with a small roller at the end of a thin lever. The lever is operated off of the throttle levers. As far as tracing the 2 wires coming off of the switch - they go into a black sheath that goes down the side of the engine and joins up with a bigger bunch of wires. Anybody out there have this set-up?

Thanks

Steve

the microswitch on the valve cover is for the transmission AFAIK

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'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)

On the early turbo models it would lead me to believe you can remove one of the 3 way valves as long as you retain the one for the trans and reroute the hose to take the place of the missing valve. I'm going to look into this when I install my kit- I just replaced one of my valves tracing a leak and turns out both were leaking. I ain't wasting money on another valve if I only need one.

I'l do my best to photo document it when I do it. New camera does good close ups!

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

I refer to them as "valves" but you can also call them vacuum switches. Same thing. The "wires" coming off the switch are vacuum lines, correct?
They are a bit heavier than a wire. If you pull the plug where these lines enter the black box on the valve cover (I'm hoping you have a black box), you can see that these are vacuum lines and not wires.

Please check and report back. The CA vehicles are different than most others so we had better be sure of what you have there.