Hose identification help

[Gretz]

This is for an 82SC.

I’ve got the engine out and am overhauling the CIS. I found this hose connected to the bottom of the airbox. I’ve never seen a hose connected in the spot before. Hose ID is 9mm, OD is 13.5-15mm, length is 500mm. Can’t find anything like it in PET and Pelican rep on the phone has no idea what it is.

[Flat6pac]

Pre 78 PET should have a hose to drain the condensed oil film outside the sheet metal to a tube.
78 and later had the oil fumes burn in the fuel going to throttle body. That’s the reason the 78 and later stumble from false air entering the intake when th e oil reservoir cap is removed.
Superfluous hose
Bruce

[PeteKz]

That's a drain line from the upper airbox, in case any oil or water get up there. It goes to a short metal pipe mounted at the front of the engine tin by the starter. That pipe should have a rubber "duckbill" on the bottom that lets fluid drain out, but prevents dirty air getting sucked back up into the airbox.

[HarryD]

Originally Posted by PeteKz

That's a drain line from the upper airbox, in case any oil or water get up there. It goes to a short metal pipe mounted at the front of the engine tin by the starter. That pipe should have a rubber "duckbill" on the bottom that lets fluid drain out, but prevents dirty air getting sucked back up into the airbox.

^^^This.

Part number 911 108 021 02. Item 7/1 as shown in the PET.

Red line shows connection to CIS Air Box.





Good discussion here: https://forums.pelicanparts.com/porsche-911-technical-forum/1162454-what-tube-near-oil-pressure-switch.html

[Gretz]

Thanks. It’s good to know why it’s there- I assume a PO got confused or decided there was a benefit to adding it. I’ll leave it off. There’s enough going on in that area, no need to keep a superfluous hose.

[PeteKz]

I left mine off to declutter the ToD. Plug the nipple on the airbox to prevent unfiltered air from entering.

[HarryD]

Originally Posted by PeteKz

I left mine off to declutter the ToD. Plug the nipple on the airbox to prevent unfiltered air from entering.

FWIW, the hole is on the inlet side of the filter. No need to plug.

In my car, I ran a tube from the nipple to below the motor to allow any oil to drip onto the ground.

[PeteKz]

It looks like that nipple may be in different places on different years. On my '80 RoW SC CIS it definitely is behind the air filter (clean side).

[Gretz]

As you can see from this pic, mine is behind the air filter but before the sensor plate, on my 82 US SC. So the worst that’ll happen is a tiny bit of dirty air will get sucked in, but it’ll still be metered.

[boyt911sc]

Ethan,

The drip tube is not applicable to your late SC CIS. On my ‘78 SC, I had a rubber stopper installed 30 years ago to keep unfiltered air going into the air box. A duct tape would do too.

Tony