Catch Can Full
Hi Z Friends,
this is my my first post on here and I’ve searched for this issue but haven’t come up with anything. My 04 Z is strictly track, I bought it this way. Caged with bolt ons. It came with a plastic generic oil catch can and it seems after every race my catch can is completely full, sometimes to the point that it’s spitting out of the breather. It’s a messy situation and was wondering if anyone know what could be causing this. One friend told me could be crankcase pressure? I’m not sure. thanks! |
Where do you race in mass?
Is the catch can vented or still attached to the plenum? Crankcase pressure would be from the rings as you know, I would do a dry/wet compression test. I believe 185 psi is the target. I had one way down at 85 dry/115 wet once... |
I race at New Hampshire Motor Speedway, Thompson, and Palmer! Hopefully racing at Watkins Glen this year. My catch can is vented, I’m not sure where it would attach to the plenum. I did notice that I was missing a hose or plug to my throttle body on the bottom side of it which points toward the driver side strut tower. I’m not sure the difference between wet/dry compression test but when we did a compression test I didn’t have anything under 170! |
Dry is dry. Just compression test it.
Wet test is when you drip a little bit of oil onto the piston rings and do it again to see if the oil seals the ring gaps. Also that hose is probably for the PVC boss that goes into your intake. You can delete it to help prevent crank case pressure or plug it back in. It's mostly for emissions. I'm running mine vented with my turbo kit. It's up to you. |
Is there anything I will see with a wet compression test that I won’t see with a dry compression test? |
Wet is to test the piston rings and cylander walls.
If you do a wet test and you gain compression over a dry, you are having pressure escape past your rings. Because the oil will seal those gaps increasing pressure. If it's the same as a dry test or with in a couple psi your rings and cylinders are sealed properly and aren't letting pressure to enter your crank case. Edit: also shows for valve seal and head gasket leaks but most the time it really shows if your cylander is worn or not sealing. |
Say my seals, head gaskets, cylinders are all good.. then what do you think the culprit of an overfilling catch can would be?
thanks for the info by the way! |
Could be a number of things, some Z owners literally chase that down for years. But it's not just to Nissan, it plagues all sorts of different cars. Many cars see this in boost. Some people find a solution, some never do.
I'd start with putting a small pod filter on the open hose behind the intake. Then do a leak down and see what we get before we explore the rabbit hole. |
Originally Posted by Thefbomb13
(Post 10934035)
Say my seals, head gaskets, cylinders are all good.. then what do you think the culprit of an overfilling catch can would be?
thanks for the info by the way! |
I'd still comp test. Its always good to know the condition and health of your motor.
Its not THAT hard. Just annoying to pull the plugs and coil packs. But not that bad. |
Originally Posted by onevq35de
(Post 10934068)
First thing I'd check before doing all the compression testing b.s. would be to check the pcv valve. Dude has this chepo c.c. vented, so he may have removed the pcv guts. That's typical for someone who might vent to the atmosphere.
I think it would have to be plugged for this to be the cause? If it was just open wouldn’t I just get misfires? |
Originally Posted by CK_32
(Post 10934042)
Could be a number of things, some Z owners literally chase that down for years. But it's not just to Nissan, it plagues all sorts of different cars. Many cars see this in boost. Some people find a solution, some never do.
I'd start with putting a small pod filter on the open hose behind the intake. Then do a leak down and see what we get before we explore the rabbit hole. Which open hose behind the intake? |
Originally Posted by Thefbomb13
(Post 10934224)
I think it would have to be plugged for this to be the cause? If it was just open wouldn’t I just get misfires? |
Originally Posted by onevq35de
(Post 10934226)
If the guts in the pcv are missing, it's wide open and the vacuum via intake is going to town. Crank case ventilation would have nothing to do with misfires.
So you’re saying vacuum created by intake that the pcv is suppose tobe regulating is pulling oil from my valve covers into the catch can? |
Originally Posted by Thefbomb13
(Post 10934231)
So you’re saying vacuum created by intake that the pcv is suppose tobe regulating is pulling oil from my valve covers into the catch can? |
Makes sense now!
I also forgot to mention that the Z was turbo’d by the previous owner.. so it would make sense for them to have gutted the PCV. Obviously the catch can oil fills under load, so there’s no real way to test it until I have a track day. Ugh I guess I’ll have to check that out and maybe run another compression test. |
Originally Posted by Thefbomb13
(Post 10934240)
Makes sense now!
I also forgot to mention that the Z was turbo’d by the previous owner.. so it would make sense for them to have gutted the PCV. Obviously the catch can oil fills under load, so there’s no real way to test it until I have a track day. Ugh I guess I’ll have to check that out and maybe run another compression test. |
Alright so I checked my pcv, it still has its guts and it seems as if it’s opening and closing fine.
But it when I went to take a pic of a pipe coming off the intake that I plugged I found another one that is not plugged at all.. tell me what you think.. |
Trying to figure out how to post pics from my phone to this forum.. confusing |
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