Smog pump removal
 

I am getting new manifolds (and exhaust) for my W126 420SE, and there is no way I am going to bolt that ugly smog pump to my new shiny manifolds. I looked at it closely, and a line goes up under my air cleaner from that disc shaped thing, but a stiff metal pipe goes behind my motor....so what is involved in removing the smog pump and all components involved? Also, my state does not do emissions tests, but if I ever had to do one, would this make me fail (still with a cat)? Thanks for any help.

Are you talking about the smog pump or the EGR valve? I thought it was the EGR system that had a hard line around the left cylinder head and under the intake manifold.

Sixto
91 300SE
87 300SDL
81 300SD

sixto, you are right, he is confusing the EGR system with the air injection system.

Good luck removing the EGR tube. You have to remove the intake manifold to get to it. But since you are getting new manifolds, you will have the intake manifold off. Should be easy then.

To remove the air (smog) pump simply remove it and plug all the connections.

OK...hmmm...well let me try to clear this up a little :) The thing that makes a hard turn around the left cylinder bank is hooked to the thing bolted to the top of my left manifold. So I want to get rid of whatever the thing is called that bolts into the left manifold with that little disc shaped thing sitting on top and everything else included. So that long pipe that makes a turn around the head goes into the intake manifold? How hard is the fitting to get to? Thanks for the info.

Wait wait wait...I just missed this and have to ask...I will have to take off the intake manifold to replace the exhaust manifolds??

I checked the manual and it does look like you at least have to remove the air flow sensor from the intake manifold since the pipe that goes from the EGR valve to the throttle body is one piece. The pictures aren't very descriptive so it's possible that you even have to separate the top and bottom pieces of the intake manifold.

It might be easier to cut and cap the pipe somewhere behind the cylinder head.

Sixto
91 300SE
87 300SDL
81 300SD
78 450SEL (sold)

Thanks....I am guessing that capping this pipe is not going to affect the operation of my motor in any way, right?

It will affect the operation of the engine. How much I cannot say. But you can see that it is going to be difficult to remove. The air mas flow plate and upper manifold must be removed to disconnect it.

See how it dissapears under the upper manifold. Even if you could disconnect it at its source, if the engine is in the car, you would not be able to slide it out. It would hit the firewall. Good luck to you.

Just for fun here is one of the air pump.

Well first of all, let me thank you for the great pictures! Just a few more questions. 1) Do you know how it will adversely affect my motor? 2) Does this thing sap any HP while in operation? 3) Would I just be better off to leave it on? My new manifolds have the hook up and all, so it would bolt right up. If I did take it off, I guess I could just cut it off right where it comes out from the motor and cap it. I don't want to adversely affect the motor though. Or I might just have to wait until this motor says goodbye and I get a new one! Again, thanks for all the help.

Digital cameras and MS Paint can do anything!

Nice job Dave..

~Paul

___________________
'91 300E, 208k miles

All I can say about it is this; The engine is designed to recirculate some of the exhaust gas directly into the intake. This flow is not included in the air mass flow sensor stream. I dont know how it affects performance. But I assume the MB engineers do and they probably did their best to optimize the engine performance with it installed.

I cant answer your questions for sure. Maybe someone else knows.

Why not just polish it up and make it look pretty. The tube is stainless and will polish up nicely.

Engine performance
 

I know someone that did the same thing with a TR7 and there have been no adverse effects to removing the EGR and Air Pump. There was a noteable difference when the air pump was removed (one less accessory running off of a belt up front), but not when the EGR was removed. Removing the EGR just made the enging compartment so much cleaner looking.

The local plumbing supply place was the only place around that had the correct thread on a plug for the air injector holes in the exhaust manifold.

Sounds great. But maybe I am a little confused on what is what. Are the air pump and EGR part of the same system? Or are they two different things? If I removed anything, it would be what is on the manifold and that pipe and I guess the little vacuum lines that run to it. Do I then need to remove a separate air pump? If I do this, I want to get rid of as much crap as possible. Thanks