Help Confirming My Diagnosis on Rear Main Seal

[Romuloux]

So I think this is pretty straightforward, but before I dive in and replace the rear main seal this weekend, I wanted some second opinions.

The car has a rough idle, but won't stall.

There is also an oil leak inboard of the front passenger side tire (started the same time the CEL came on).

Pulled the pans, and the oil appears to be coming from where the transmission and engine mate together.

PCV blows out a good stream of air from the vent hole that is pointing towards the firewall at high idle, low idle, the air flow is negligible.

The codes that have been thrown are:

P0299 - Turbocharger/Supercharger Underboost Condition
P2279 - Intake Air System Leak
P2187 - System Too Lean at Idle Bank 1

So my thoughts are that a bad PCV/air oil separator has blown out/in the rear main seal. Also checked and the DV is the updated D, piston style revision.

Course of action is to replace the PCV and rear main seal. Just looking for any other thoughts before I go through the pain of dropping the trans. Am I missing something?

Thanks

[NitroViper]

put the car on a lift or jackstands, take off the cover to the rear where you take the torque converter bolts out. Start the car... spray brake cleaner up in there trying to hit the rear main seal and see if the idle changes.

[Smac770]

The PCV should be sucking in air at the vent hole at idle if the diaphragm is torn. If you place your finger over the hole, the idle does not smooth out?

Usually if there's a rear main seal leak, there's usually a picture showing a mess of oil inside the inspection port on the transmission bell housing (if you have a ZF auto).
I can't find the thread I was thinking of, so here's this:

You can see it on the transmission in the second picture here: https://www.pbeuropeanservice.com/po...rear-main-seal
It's the hole you go through to undo the three bolts of the torque converter to the flywheel (flex plate, whatever, the object the starter spins).

[Romuloux]

Thanks, will open up the port on the trans this evening and double check. Will also spray some cleaner at the rear main to see if the idle smooths out.

As far as the PCV, that is what got me a little confused. It was most definitely blowing air out. I replaced it about 3 years ago when it had a rough idle and the PCV was sucking air in.

No change in behavior/idle whether the hole on the PCV is plugged or not.

[old guy]

Thanks, will open up the port on the trans this evening and double check. Will also spray some cleaner at the rear main to see if the idle smooths out.

As far as the PCV, that is what got me a little confused. It was most definitely blowing air out. I replaced it about 3 years ago when it had a rough idle and the PCV was sucking air in.

No change in behavior/idle whether the hole on the PCV is plugged or not.

Whether the PCV is blowing air or sucking air it is most definitely defective. Did you replace it with an OEM PCV breather valve?

[Romuloux]

Whether the PCV is blowing air or sucking air it is most definitely defective. Did you replace it with an OEM PCV breather valve?

Yep, replaced straight from the dealer parts desk (3 years ago now). Will replace it again with the rear main.

[NitroViper]

Thanks, will open up the port on the trans this evening and double check. Will also spray some cleaner at the rear main to see if the idle smooths out.

Start the video below at 6:00 and youll see how to do it.

[Romuloux]

Sprayed some parts cleaner in the access panel, idle smoothed out like it should.

Looks like I'm dropping the trans this weekend!