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Hey all, I have a 2003 350z that I am learning how to drift on and it will not stop dumping oil out of it each event. We have tried a lot but nothing seems to be working. Starting from the very beginning:
Bought the car and the driver rear pcv port had a little breather filter on it, which was greatly leaking oil all over the exhaust, transmission, and undercarriage. So I removed the breather filter and routed a hose from there to my catch can and Td into the intake side.
It started leaking in the spark plug tubes and the engine got a crazy suction. When we would pull the oil cap off, it would be suctioned to the tube. And the car made a whistling noise and would whistle loudly when I shut it off.
Tried removing the rear pcv hose off from the catch can and left it the hose open to vent to atmosphere. It was a long hose that I left up by the catch can. I reconnected the catch can as it was.
This stopped the suction, but dumped oil EVERYWHERE. My entire bay and wheel wells and undercarriage were all covered!
We tried plugging the rear pcv port hose
It started doing the same suction thing it did before & this caused it to leak oil again from all of the spark plug tubes.
Now we tried a second catch can, which I’m newer to Zs but I’ve never seen anyone else have to do. We have the pass side catch can set up as it was. The rear pcv port was have route to the second catch can intake port and we have a little breather filter on the out port.
No suction and the oil leaks are horrible out of the spark plug tubes and out of the catch can (which I expected some from the filter.) This second catch can also fills up very fast, it had 2 inches of oil in it after just a half day of drifting.
I know OEM setup is that rear pcv port has a hose that routes to the intake. However with how much oil keeps dumping out of mine, I can’t imagine that’s good to be flowing through the intake system.
Car is an 03 with about 265k miles and it does not seem to have any blowby at idle (we did the paper test.)
**Addition: I have the metal valve covers and we have replaced the gaskets twice now from CZP.
Any help or suggestions are appreciated, thanks in advance!
Here are some photos of the current/last setup mentioned above.
This is the rear pcv port Im referring to. This is the hose currently coming off it which we have routed to the second catch can shown below.
This is the second catch can mentioned.
This is my normal catch can on the passenger side which seems to be the standard setup. No issues with this but wanted to add it for reference.
Last edited by ZigZag03; Oct 22, 2025 at 08:18 AM.
Plug the one on the intake , you don’t want to suck unmetered air as you are doing.
ran from my Pcv to a large moroso catch can with breather , then I ran another line from the drivers side valve cover to that same breather tank.
after every event I would empty the catch can that’s part of the breather , usually had a cup of oil in it
this one is similar, and what I would buy if I did it again
My intake is aftermarket and doesnt even have the port on it so no issues there.
So do you have yours on the driver side T'd into it? Because there are 3 lines total right then? The two on the passenger side (PCV and intake) and then the one drivers side line. Id be interested to try this out with the filter added. When I tried before it was still leaking and had that weird suction but we didnt have a filter on it which I think could help.
To me, this sounds like you're getting to much crankcase pressure and it's blowing out your valve cover seals. This is likely happening because you're venting straight to atmosphere on the driver's side cylinder bank (no crankcase vacuum generated since connection to intake pipe pre-TB has been deleted). Pressure would be at it's highest when under wide open throttle conditions. Under idle or low load conditions, crankcase vent duty switches to your passenger side catch can since it's directly connected to the intake plenum (after the TB - which generates high vacuum). But because the driver's side is open to atmo, you're intake is sucking in unmetered air and making that hissing sound at the driver side catch can. I also recommend checking the PCV crossover tube between the valve covers, you mentioned you're running the aluminum covers, was this hose replaced when the cover replacement was done? The original PCV hoses are prone to cracking as they age out.
Are you still using the OEM PCV valve in the bank 1 valve cover? Most guys either replace this with a AN fitting adapter (no bead valve) or drill out the OEM valve when switching to a pure "vent to atmosphere" setup.
Other things that could exacerbate the problem...
1) No sump baffling.
2) Oil is becoming foamy or aerated.
3) Piston rings are shot. (excessive blow-by)
The 2003s have known oil starvation issues in prolonged high G scenarios like drifting. Without proper sump baffling this can lead to pickup tube starvation and oil foaming/aeration/misting inside the crankcase. If you're running a stock oil pan, you should immediately replace it with a baffled unit. I wrote a review post about the Z1 pan on these forums.
Let us know what your compression and leak down tests results are.
Cheers!
-Icer
Last edited by icer5160; Oct 22, 2025 at 01:31 PM.
Talking about the crank case ventilation, Is it better to keep it under vacuum with a pcv/ccv and catch can or with a breather in to the atmosphere..... Does it make any difference? At the moment I have a catch can installed but it is under the plenum vacuum.
Dumping Oil - Crankcase pressure issues
