The Pyramid of Death! A 4th point above for CIS

[75 911s]

Hello all,

I came across an oil breather tube on my 1975 stock CIS setup and in the spirit of sharing information I thought I would go into more detail regarding another potential leak source that is generally in the same area as the so called "Triangle of Death"

In what I'm calling the Pyramid of Death which now includes the CIS airbox oil drain tube.

The triangular pyramid base being the oil breather, the oil pressure switch and the Oil thermostat on the back of the engine - and now the top of the pyramid being this oil overflow tube and valve.

Applicable years goes here

Here is a picture of the oil vent tube.




Pictures courtesy forum members

The setup consist of 3 pieces.

1.A fuel hose Part #: 999-180-030-50-OEM 7x12mm (about 10 inches long) going from a nipple directly underneath the airbox housing and connecting to:

2. The breather tube nipple 911 108 021 02 which goes through a hole in the engine tin on the back of the engine and is held in place by a bolt on the oil cooler: Which in turn has a rubber drip "valve" that allows for oil to seep out, but also keeps air from entering the tube.

3. The 253-260-180-OEM Crankcase Vent Rubber Valve





When you overfill your oil tank, oil can flow through into the airbox and then drain through this hole near the back, down the hose, into the plastic tube and seep through the rubber valve onto the Earth.

[TargaT]

Thanks, I just found the source of my oil leak. Had to drop the motor to find it. Mine had some kind of a funny plastic plug in the spigot of the airbox. Not sure if this was intended to plug it but it didn't.
No drain hose.

Joe

[SalParadise]

Thanks for sharing this. Nice photos.

However, that is not a stock '75 CIS setup. It has the later '76 - early '77 mods.

[75 911s]

Originally Posted by SalParadise

Thanks for sharing this. Nice photos.

However, that is not a stock '75 CIS setup. It has the later '76 - early '77 mods.

I should have clarified that the photo was one that I borrowed of an engine that was dropped out of a car so that I could clearly show the catch tube. In other words that isn't my '75 engine. :-)