What is tube on driver side of engine

[Scutch]

Hello,

What is this tube that runs along the plugs side of the engine and has little tubes that go into the head right near each plug? Then it eventually connects to a vacuum line on my carbs.

That pipe has a crack and is blowing air. I assume is is some EGR thing.

Can that split in the pipe cause anything other than a loss of pollution?

This is an 1968 automatic 230s.

Thanks
Eddie

[Mark DiSilvestro]

What you've described is not EGR (Exhaust Gas Recirculation) but an AIR (Air Injection Reaction) antipollution system, used on some US-market 6-cylinder Mercedes from 1968 to 1970. If all of your AIR system is still there, you should have a belt-driven airpump mounted below the power steering pump, connected by a hose to a check-valve on the end of that tube, to force air into the exhaust ports. The vacuum line to the carb should be connected to a backfire-suppressor valve installed somewhere between the pump and check-valve. If your original AIR components are damaged or missing (and probably unavailible), and you're in an area that isn't emmissions-testing '68 cars, your best bet may be to remove that tube and plug the holes in the head, as most likely you actually have exhaust leaking from that crack. Alternately it may be possible to braze or weld the crack.

Happy Motoring, Mark

[Scutch]

Thanks Mark, that's what I have. All that stuff is there. Could you explain a bit more about why it is there. Other than polluting more, is there any disadvantage to disconnecting the whole setup? Any advantages?

Thanks
Eddie

[Mark DiSilvestro]

Originally Posted by Scutch

Thanks Mark, that's what I have. All that stuff is there. Could you explain a bit more about why it is there. Other than polluting more, is there any disadvantage to disconnecting the whole setup? Any advantages?

Thanks
Eddie

It's supposed to be a sort of afterburner (In fact that's what Mercedes calls it in the factory manual), introducing air downstream of the exhaust valves to consume any residual unburned fuel that might otherwise escape out the tailpipe.

Advantage of disconncting the cracked air-injection tube and plugging the ports in the head is eliminating a possible underhood carbon monoxide leak.

Disadvantages of disconnecting it include extra hydrocarbon emmissions (assuming the system is still working at all after 39 years), risk of failing an emmissions inspection if you're in an area that tests cars back to '68 (assuming an inspector today would even know that a '68 Mercedes is supposed to have an air injection system), and the car won't be 'stock' anymore if you're a real fanatic about originality.

Also, according to my factory repair manual, the 230 airpump and power-steering pump share the same belt, but the power-steering pump is fixed and the airpump is used to adjust the belt on this setup. So removing the airpump may not be an option, unless you can get the adjustable power-steering pump bracket and shorter belt off a non-airpump model.

And removing the air hose and injection tube, but leaving the airpump spinning in place and open to the atmosphere might produce more noise and shorten the remaining life of the airpump (which doesn't owe you anything after 39 years anyway)


Happy Motoring, Mark

[todds]

On typical American and other cars these air injection systems are notorious for burning exhaust valves and causing leaks. Nothing like a small blowtorch aimed in your exhaust to scrub away heat! On the other hand, if it hasn't hurt anything after all these years it probably won't ever. Perhaps the Mercedes version is more well engineered or the valves themselves are higher quality. My 67 230S doesn't have that system, but it was bought in Salem, MA. Perhaps yours was a CA model?

[Scutch]

Mark,
You sent me this response a while back. I now need a fuel pump. The only ones available for under $400 from Mercedes are the horizontally mounting ones. But they won't fit because of the additional mounting steel from that AIR pump.

Have you dealt with this at all. I have another 111 with the "normal" power steering pump setup. I wonder if I can just switch the hardware?

Have any ideas?

Thanks
eddie

Originally Posted by Mark DiSilvestro

What you've described is not EGR (Exhaust Gas Recirculation) but an AIR (Air Injection Reaction) antipollution system, used on some US-market 6-cylinder Mercedes from 1968 to 1970. If all of your AIR system is still there, you should have a belt-driven airpump mounted below the power steering pump, connected by a hose to a check-valve on the end of that tube, to force air into the exhaust ports. The vacuum line to the carb should be connected to a backfire-suppressor valve installed somewhere between the pump and check-valve. If your original AIR components are damaged or missing (and probably unavailible), and you're in an area that isn't emmissions-testing '68 cars, your best bet may be to remove that tube and plug the holes in the head, as most likely you actually have exhaust leaking from that crack. Alternately it may be possible to braze or weld the crack.

Happy Motoring, Mark

[280EZRider]

Originally Posted by Scutch

Hello,

What is this tube that runs along the plugs side of the engine and has little tubes that go into the head right near each plug? Then it eventually connects to a vacuum line on my carbs.

That pipe has a crack and is blowing air. I assume is is some EGR thing.

Can that split in the pipe cause anything other than a loss of pollution?

This is an 1968 automatic 230s.

Thanks
Eddie

About 10 years ago, while I and car were out of the country, my cat got stuffed up due to a frozen air pump on my M110. After these units mysteriously disappeared, I removed the now useless tubes from the air pump and plugged the manifold-pipe at the check valve with just a rubber cap (plus a little aluminum foil inside the pipe to shield the cap from heat). Since the majority of exhaust pressure goes straight through the exhaust manifold, I have yet to encounter any leaks.

[Scutch]

I took off everything already a couple of years ago related to the AIR system. I wonder now about removing the pump and pulley that sits under the power steering pump and pulley.