What is this piece on the bottom of the CIS airbox?

[ADDvanced]

See photo. Metal pipe that goes into the bottom of the airbox. What is this? Should it be sealed somehow? My engine has had so much silicone where it shouldn’t and I’m having trouble even finding the name of this part so it’s hard to find out if it needs o rings or what. Also I tried blowing throw it on both ends and nothing moves it acts completely clogged. Good or bad?


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[ADDvanced]

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[Walt Fricke]

ADD - cardinal rule for seeking advice is to identify your model.

I can guess that this is not a late SC - it has the flexible injector lines. Someone may recognize it by other characteristics, like a 73.5T. But is or was this engine from a Sportomatic, which has some extra plumbing? Or is it a US 2.7 and it is part of the exhaust gas recirculation system.

[boyt911sc]

Originally Posted by ADDvanced

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That steel tube goes to the EGR.

Tony

[ADDvanced]

77 911s.

Should there be an o ring?


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[gled49]

looks like the upper part of California EGR system.

[ADDvanced]

Do I need it???


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[Walt Fricke]

You in California? Or some other state which, for emissions purposes, requires you have all the EGR equipment? Probably then yes.

If where rules are laxer, and all you have to do is pass a gas sniffing test, then maybe not. Without the EGR pump and plumbing and all the rest, you probably should just plug the hole in the plastic air box, if it is screwed in there.

[ADDvanced]

So.... I have no idea where my car was from originally, but I don't have an EGR system. I don't have air injection or a smog pump. This pipe is clogged; it looks like someone jammed a piece of metal in the end of it, and threaded on another adaptor to seal it.

I really really do not want a vacuum leak on the bottom of my airbox. How are people sealing this area? The metal 'hex' on the bottom o the airbox is molded into the plastic, afaik you cannot unthread it.

[Walt Fricke]

In the absence of advice from someone who has dealt with this exact issue, if you are correct that the piece cannot be unscrewed from the plastic of the air box (so a plug could be screwed in in its place), you could just cut it off at that point and fashion a plug. JBWeld (or just about any other adhesive) ought to hold it in place just fine. If you leave a rim on the plug which extends beyond the diameter of the hole, the vacuum in the air box will help keep it in place. If you have or add a pop-off valve in the air box (a good idea with this model), that should prevent backfires from trying to blow the plug out.

I've capped an unused opening in the left side of my 3.0's air box with a plastic cap glued in place - has worked fine.

[Henry Schmidt]

You are correct. It is an EGR pipe.
The plug will unscrew but it can be a real pain. The problem is, if you torque on it toooo hard it can break the air box. An electric impact that can generate a consistent hammering generally works well.

The threaded piece can then be glued or welded for a somewhat permanent seal.

If removing the EGR will prevent smog compliance (IE: California) send me an email. I can help with that.

[ADDvanced]

No worry about smog here. I'm going to try to use an electric impact to remove it, and report back.

[tops911]

I used to have a 1978 SC and if I remember correctly someone here on Pelican told me that an oil tank drain plug was an exact fit to seal the airbox. My SC had a non functioning EGR that had the pipe crimped to seal it.

[tops911]

I used the aluminum drain plug seal along with the oil tank drain plug to seal up the air box

[Henry Schmidt]

Oil tank plug, sump cover drain plug, some transmissions plugs all fit. It's a fairly common plug on Porsches.

[tops911]

It was probably Henry that told me to use the drain plug!