Oil Leak - Cylinder Head Cover - Cyl 4-6

[amcleod1]

996 C2 MY2000 Tiptronic

I've just noticed a small oil leak coming from the Cyl 4-6 Cylinder Head Cover. No oil dripping to floor as yet. The exact location is shown in the following diagrams (front RH-bottom corner when looking at engine). I'm wondering if its just the cap (Item 48) that I need to remove and replace. I can't seem to find anything about them in the factory repair manual, so any suggestions on part nos. and how to remove and re-install would be greatly appreciated.

[Dharn55]

There is a breather tube that runs from the AOS To a connection on the top of cylinder head 4-6 above where you are seeing the oil. This is often the source of oil in this area.

I believe the cap you are referencing is a freeze plug that is friction fit into the engine and not typically the source of a leak.

[amcleod1]

Thanks. I had cleaned the area thoroughly, and saw no obvious signs of a leak from higher up. I'm hoping its not the freeze plug as it sounds like a fairly sizeable job to refit.

I will clean again and take a closer look again for a higher up leak.

[av8sky]

I had an oil leak similar to yours and I needed a cam cover reseal. I am normally a DIY guy but this looked over my head. I cleaned the area several and the leak showed up in the same spot. When my indy shop did the work he told me he replaced all of the different seals (vario cam) and parts that could leak are on the cam cover. That was 3 months ago no leaks. My 996 is an 03 and the repair was around $850 out the door. I hope that helps.

[amcleod1]

Ok - its not the freeze plug. But still hard to see exact source of leak as its not much of a leak. I'm now looking at either (1) spark plug #4 tube seal and (2) the AOS breather tube connection to cylinder head 4-6 as there is grimy oil residue there. Spark plug should be relatively easy to get to by removing muffler. The Breather tube is buried tight under a large coolant hose and many other smaller hoses cables. Need to find a clear weekend of no baseball.

[Dharn55]

Also take a look at the seal around the cam advance actuator solenoid. These commonly leak.

[amcleod1]

Ok all fixed.

The original oil leak was the #4 Spark Plug Oil Protection Tube leaking.

Dropped the muffler, removed the coil cover plate, coil #4, spark plug #4, pulled the oil protection tube, replaced both inner and outer o-rings (bit of lube) and reinstall. 5 days later not a trace of oil. Presto.

Also On day 5 I replaced the AOS breather tube connection piece (with new o-ring) and new o-ring on the breather tube as well. Very tight under all those hoses, and cable bundles. Hopefully this will fix the small oil sweat around this area too. (suspect it was due to a loose bolt holding the connection piece to the cylinder head).