CA18DET FILLING OIL CATCH CAN WITH OIL

[nickarmacy]

MY CA18DET IS FILLING THE CATCH CAN WITH OIL NOT ALOT BUT ENOUGHE FOR ME TO NO SOMETHING IS UP HOW DO I FIX THIS PROBLEM THIS MOTER IS FULLY BUILT WITH TOMEIE 260 CAMS FCP PISTONS AND GREADY HEAD GASKET MAYBE ITS PLUMBED WRONG ??? HEARS A PIC

[Towncivilian]

Do you have an OEM PCV valve?

[1200ute]

How much oil is going in the catch can over what duration and what sort of driving?

Probably not the best way to have your catch can set up but someone else can give you info on that.

[float_6969]

Yea, not a great setup there, but as 1200ute said, how quickly is it filling.

[TheMAN]

catch can not hooked up properly AT ALL, that is the problem
read this thread and hook it up the way I said
real-ca18det-catch-can-popping-dipstick-t557961.html

[Buddyworm]

The CA's breather system sucks and it'll still pick up a ton of oil in your catch can even if it's routed "properly" as per factory. Especially if you see sustained high revs.

This is how I've got mine set up:


It's a drift car, sits on the rev limiter at practice, sees redline daily on the street, turbo is TD06-17c and pushes 14psi all day. I pick up zero oil in my can with vacuum being pulled from the PCV under manifold vacuum conditions, and intake pipe under boost.

Notice I've got the exhaust-side breather capped off.

[float_6969]

I'm sure the catch can doesn't fill. It rarely has any air passing through it. Especially the way you're driving it. You also don't have any way to bring fresh air into the system. That is NOT a great way of setting up the PCV system. I'm sure it doesn't fill, but it's also not doing anything a PCV system should do either.

[Buddyworm]

I agree it's not the ideal way to set up a PCV system, but it's a simple way to create a pressure gradient between the intake system and the crankcase while also relocating the valve cover breather connection away from Nissan's brilliantly designed oil drain/breather passage. Everyone knows the problem it creates draining oil out of the head under heavy load and the exhaust-side breather connection is situated pretty much right over top of it. Pool of oil going down + blowby coming up = oil up the breather tube.

The drawback with my system, as you correctly pointed out, is the lack of fresh air being drawn into the system and evacuating contaminant-laden blowby gasses but my major concern was creating a relatively low pressure area to evacuate the higher pressure from the crankcase.

Because the PCV valve is Tee'd into the intake pipe breather hose it's not the most effective setup at idle as it largely bypasses the crankcase circuit but with the PCV valve closed under heavy load, when crankcase pressure evacuation is critical, the only flow path is crankcase > intake-side breather > catchcan > intake pipe.

It works well and I don't launch dipsticks.

My next step once the snow flies is to cap off all valve cover breather ports and plumb the catch can directly off the connection on top of the oil filter flange and vent to atmosphere.

[float_6969]

connecting straight to the top of the oil filter mount is what I did. BUT, I didn't vent to atmosphere. I have it connected to an oil/air separator from an SR20. The outlet is connected to the PCV valve on the intake manifold, and another valve I connected to the suction side of the turbo. The valve covers are left open to the atmosphere with filters on them. This way, fresh air is constantly being drawn into the valve covers, into the head, DOWN the oil drains (bringing oil with it), and then back out, up to the separator. I haven't had a chance to beat on it yet and see if this works, but I'm pretty confident in it.

[Buddyworm]

I like that idea but I'm leary of running open breathers when I'm pulling vacuum off manifold and suction pipes. Ideally I'd run it through one of those check valves 45'd into the exhaust system.

With your setup I'd be worried about going lean under a part throttle, open loop condition where those breathers basically act like giant vac leaks.

What's your experience with driveability? Got any pics?

[TheMAN]

they don't act like giant vacuum leaks, the PCV valve meters the amount of air going into the intake manifold

[float_6969]

I have a standalone, so I can leave them open. If you're running a MAFS system, you can tie them into the intake, pre-turbo, post MAFS.

[TheMAN]

and put a catch can/oil separator in between

[float_6969]

In theroy, you wouldn't need it. The air should only move one direction. I'll get pics and a writeup if it works.

[TheMAN]

it moves the other way under boost

[float_6969]

In the stock setup, yes. Like I said, once I can confirm it works, I'll get pics and a writeup.

[Ca_Silvia]

I was filling my catch can on a brand new rebuild, i was originally running the 5/8" hoses to a catch can (exhaust side only). Switched to 3/4" hose and now it won't fill 1 drop. The smaller hoses lead to higher velocity of air inside the hose which makes it easier to pick up fluid. Increasing to the larger hose, decreases that velocity and everything is perfect now.

Catch cans on the CA always lead to lengthy topics on their design and plumbing but no one ever thinks of the hose size that is being used.

[float_6969]

This is very true! When I first had mine setup, I was using a 5/8" hose coming off of the fitting on the top of the oil filter mount. It was pulling oil all the way through the SR20 oil separator and pulled a half a quart of oil out of the pan in less than 10 min of beating on it. I switched to a 1" hose and I've never had another drop of oil make it past the separator.