What is this part on the passenger side?
 

I took off my passenger side coolant hose on the top of the engine right above the engine mount and noticed this black thing that is plugged into the top. There is some kind of long hose of some kind attached to it. Looks like some kind of 45 degree elbow valve.
https://cimg1.ibsrv.net/gimg/rennlis...057784780.jpeg
Located just to the right of the electrical wire connector


Any ideas what this? Just thinking it could be an easy replace while your are there item?

crankcase vent valve (check valve). it connects to the long gnarly AOS hose. real pain to get that retaining bolt started on my boxster. Not much to the part so I don't think it requires replacement.

Year, make and model please. The elbow looks like a breather. Could be part of the fuel and evap system but I'm not finding any part that looks like that on a 996.

#6 here http://www.autoatlanta.com/porsche-p...section=104-10
click on the part number for a picture of the crankcase breather

Yup, breather, hose goes to AOS as stated above. Easy to replace, the one on my 2000 had a leaky o-ring, so I swapped it out. I wouldn't replace it unless it is leaking or damaged.

1999 C4 manual cab

Cleaning or replacing it can extend life of the AOS.

Yeah that long hose looks very difficult to remove and reattach to the AOS.

The breather is attached by 1 bolt to the head. Remove it & pull up on it, making it easier to release the AOS hose by pinching the integral clamp. Check the o-ring for damage.

Ok sounds good. The hose replacement seems hard but the breather itself pretty simple.

You don’t need to detach the hose on the AOS side. It has a plastic clip so you can detach it on the Y vent end.

Thanks guys!

Having some problem getting the hose detached from the plastic elbow vent. Got the 10mm bolt undone and the elbow is free.

I've tried several things including squeezing the hose, squeezing at 6 and 12 o'clock and 9 and 3 o'clock. There are no gray colored clips showing where or how to squeeze. What am I doing wrong?

Post a picture. I think I've seen at least two different versions.

OK here is a pic. Disregard the white liquid paper mark which was just for reinstallation purposes.
https://cimg9.ibsrv.net/gimg/rennlis...8579f30bd8.jpg
https://cimg0.ibsrv.net/gimg/rennlis...89024f9d1f.jpg