Empty bracket on my 75 911S

[crashr]

I recently purchased my first Porsche. It's a 75 911S and it had 2 P0. For some reason on the drivers side next to the fan there is a big metal bracket with nothing attached to it. What used to sit here? It was a california car, did it have anything to do with polution control? The bracket is about the same spot as the air conditioning compressor but on the opposite side.

[Rot 911]

Car probably used to have an air injection pump for pollution control.

[Tim Walsh]

smog pump or air pump? I think that's what it is. those are pollution control devices. I'm only taking a stab at it since I've got a 73 which doesn't have a bracket there.

[david lipman]

It's for the air pump. I just removed mine. It's held on by three nuts. You'll want to replace the bracket with some sort of spacer (I used old lug-nuts from a GM car given to me by Marc) to keep tension on the studs.

you may have to remove the air rail and the "anti-backfire valve" it attaches to to have enough room to slide it off.

[thrown_hammer]

If you want to remove the "rail" under the engine you will need plugs for the heads where the rail screwed in. Mercedes transmission drain plugs with copper washers fit perfectly. When I put my headers on I had to remove the rail. I have an extra drain plug if you want it to take to the Mercedes dealer to match it up let me know.

[david lipman]

right-on, I had a local parts store that knew what I needed.

[crashr]

you may have to remove the air rail and the "anti-backfire valve" it attaches to to have enough room to slide it off.
You'll want to replace the bracket with some sort of spacer (I used old lug-nuts from a GM car given to me by Marc) to keep tension on the studs.

By rail to you mean the brace or bracket that held the air pump in place (it sits on a 45 degree angle)... Why do I have to replace it with a spcer? What do you mean by keep tension on the studs? I just unbolded the bracket and left it.. obviously from your replies this is not a good idea.

[crashr]

Also how exactly did the air pump work... how did it help pollution control?

[Oldporsche]

The air pump pushed air into the exhaust system helping helping supply more oxygen to consume more of the unburned gasses that exited the engine. This was complimented with the catlytic converter that helped keeping that exhaust hot. The result was that at the end of the tail pipe, the emissions were down. Even if the combustion had not taken place in the exhaust system, assuming the air pump was operating it would have diluted the exhaust sample probably lowering the grams per mile of emissions.

For our air-cooled car, and the position of the exhaust, this was like operating our engines over a campfire!

Good luck,
David Duffield

[david lipman]

by rail I mean the tubing that connects the air pump to the heads of the engine. It may have already been removed on your car. I don't have a diagram handy, but it is in my owner's manual. I think you'd want to keep the studs tensioned to keep the cam cover on the drivers side from warping/leaking, but that may not be a real problem.

the air pump worked, I believe, by pumping fresh air into the exhaust, allowing it to combust more completely in the thermal reactors.

[Paco Anton]

Dennis,

Just in case here you are a pic of my engine with the air pump.

[Jdub]

David:

Very interesting bit of information about tensioning the three threaded studs from the driverside cover that holds (held, in my case) that air pump. I simply put a bit of clear plastic hose over my studs to keep the threads from getting bunged up.

Can anyone else comment on the need to tension these studs?

John

[Jim Sims]

Jdub, Depends on how many of the nuts you think you need to keep the chain case sealed (oil in and dirt out). The gasket may be sticking and holding the top sealed where the studs are not longer clamping but I would prefer to have all the fasteners tightened. Make bushings or sleeves of metal tubing, slip them on the two top studs and use the original nuts to clamp the joint tight. Jim