How and Why of Adding a Catch Can

[Local Apparent Friday]

Greetings all!  Throwing up a tek for details on the catch can. I am posting this in the general category because I expect a similar issue and procedure for the V6 as well.  Pictured is an airaid intake, procedure is the same regardless of what induction system you are running.

 

Total Cost is about $60, total time to complete is about an hour of actual work, and another couple of hours figuring out where you want to mount the can. 

 

 

Materials List:
(1) Catch Can

 3/8" Fuel Hose (length will depend on your install location, I bought 12' for mine and had extra.  Generally available from your local hardware store/marine supply and costs about $2.20/ft at the time of writing

(2) 3/8" Barbed Tees

(8) 3/8" hose clamps in addition to the 4 factory ones that you can reuse.  Linked are the factory clamps if you want to maintain the look.  Alternatively, you can source stainless hose clamps locally.

(2) 10 flat washers (.14 cents each at ace)

(2) 10-32 nyloc nuts (.28 cents each at ace)

Stainless dish scrubbers

Tools:

A pair of plyers for the hose clamps

A flat head screwdriver if you are using aftermarket hose clamps

A metric 4 allen wrench for the included hardware

A 9mm wrench for the nylocs

#21 drill bit

 

 

 

I'll save myself a long winded explanation...if you're not familiar with PCV systems and their history, you can read all about it here.  Now if you're thinking about it, you've realized that you're sucking all that gunky air full of oil and gas vapors into your intake, which leads us to where we are now.  For those that were watching the engine replacement thread, I mentioned that we tore down 3 separate VK56DEs from three different vehicles (titan, armada, and NV3500,) all three had a thick layer of oily goo and residue in the downstream intake runners of the intake manifold runners and the head, as evidenced by these pics:

 

 

 

 

 

 

 

Easy enough to clean with some brakleen and rags, but we want to eliminate that from the system to prevent gumming up of the valves and injectors, smooth out the airflow, and also prevent the engine from burning that low octane gummy gunk. while still maintaining the integrity of the PCV system.  If you are looking at the VK56DE induction system, you will see 4 hoses.  There are two 3/8" hoses on the front of the engine that go directly from the PCV valves in the rocker covers to the intake known as the PCV hoses, and then two larger 5/8" hoses on the back of the rocker covers that run to the intake tube, known to Nissan as blowby hoses.  In checking the intake, we see that the gunk is introduced at the PCV intake, and that the unregulated blowby hoses do not seem to be introducing any garbage.  As to the reason there are 2 separate systems, my research says that the blowby hoses are meant for operation range wherein the vacuum is not enough to open the PCV valves.  Here are pics showing the clean intake and tube, thus isolating the PCV system as the culprit.

 

 

 

 

 

 

Enter the amazon special $23 Alavente catch can.  If this item is discontinued by the time you check, just do a search for "catch can" and there will be many.  You can spend as much or as little as you want on these things, but the general idea is that the air has a chance to condense with the oil settling out in the catch can and clean air returning to the intake.  Here are some pics of the can.

 

 

 

 

 

 

This system needs to be a closed system to maintain the integrity of the PCV and to not suck unmetered air into the engine.  This particular (cheap) can has a "filter" but this is basically just a couple holes drilled through a small removable compartment.  More expensive cans may feature 50 micron metal filters.  In my installation, I cut apart the included filter and used the screen and filter material to make my own.  I did this because I will be filling the can with coarse steel wool to promote condensation and filtration, and we don't want to suck small metal shavings into the engine.  I recommend you use stainless dish scrubbers, which have a much coarser texture and are available at the dollar store, but I was trying to get this done with what I had on hand.  I may switch it out in the future.  Important to note is that I reversed the labeled in/outputs so that the air going out hits the little filter, as opposed to coming in.  You will not use the teflon tape, 4 of the o-rings, the cheap hose, or the 4 larger bungs.  Using the supplied nuts is optional, I swapped for 10-32 nylocs.

 

 

 

 

 

 

For the 3/8" PCV system, you'll use the smallest of the barbs that are included with the filter.  Additionally, you'll need a number 3 o-ring for the dipstick, and I gently filed off the anodization to make it easier to see the oil level when I check it.

 

 

 

 

 

 

Next, find yourself a nice plum, flat spot to drill into to mount the oil catch can.  This looks like a  good spot.

 

 

 

 

 

 

I kid, I kid.  Please don't drill into your battery, just checking to see if you're awake.  In order to promote condensation, the can wants to be away from the engine heat as much as possible, while still being accessible enough for you to empty regularly.  Unfortunately, most of the good spots on the NV are nigh impossible to get to the backside of (ie that sweet flat spot on the inner fender in front of the battery) and I'm not one for self tapping screws.  In my particular instance, I opted for the front of my brand new airaid box, but I will likely move this to the lower radiator support once I tackle the bumper project.  Putting it there would get it down into the cool air stream, and would still be easily accessible from the bottom after you remove the plastic skid guard for the oil change.  At this point, you need (2) 3/8" barbed tees, available from home depot/lowes in either plastic or brass, a bunch of hose clamps, and 3/8" fuel line.   Connect everything up so that it goes PCVs from rocker covers to a tee to catch can, then out to a tee and to the intake manifold ports, and you're good to go.  Zip tie everything where it makes you happy, and off you go.  Also I added (2) #10 flat washers on the bolt head side and (2) 10-32 nylocs in place of the included hardware that came with the oil can.

 

 

 

 

 

Now just remember to empty the catch can during oil changes so you don't suck everything up into the intake. I am in the process of "breaking in" this newly swapped engine and will post back with a report of what kind of condensate levels I am seeing, but generally these things work as evidenced by any good google search or time spent around performance vehicles.  I do not have access to a 4L, but I would expect similar gumming and a similar procedure.  my future modifications are to swap to the spring style factory clamps (I ran out) and possibly see if I can find black Tees instead of white, simply for continuity. 



Thanks for reading, best of luck.  Fair winds and fun adventures!

-laf

Edited June 27, 2022 by Local Apparent Friday

[radin2son]

There are some that can and others who can’t... Wish I could. 

 

Thanks for the  tutorial. 

Edited June 25, 2022 by radin2son

[Local Apparent Friday]

Come to the Adventure Van Expo in Chattanooga in Oct and I'll do it for you. 

Edited June 25, 2022 by Local Apparent Friday

[radin2son]

Good reason for the meetup suggestion. 

[Local Apparent Friday]

We'll be there, portable shop in tow.

 

 

Edited June 25, 2022 by Local Apparent Friday

[Local Apparent Friday]

Quick update....I have driven exactly 53 miles and am already seeing oil residue in the can.  Headed out on a 150+ mile adventure tomorrow in search of an airbag recall, I'll pull the can after and post some pics.

[Local Apparent Friday]

Pulled the can when I got home, there is already a thin layer of oil covering the bottom of the can as pictured.  It has been 215 miles since install.  I will continue to monitor the can via dipstick only, and I'll post pics at my "break-in" oil change of 1000 miles.  After that, I'm planning on running a 5k interval on full synthetic for the first full cycle.  I'll Post at the time of that oil change, and at 10,000 miles I'm going to pull the intake manifold back off and see what it looks like inside.  Based on this though, I think everybody should have one.  That's all being dumped into your engine and gumming things up.

 

Also, based on the anticipated small metal shavings, I'll be switching to stainless dish scrubbers the next time I happen by a dollar general, and recommend anyone else do the same.

 

-laf

[Local Apparent Friday]

Changing the oil tonight at the 5000 mile interval ahead of our travel this weekend.  Catch can is a little more than half-full of oil.  I'm using the dipstick to mark the level.  Catch can is 400ml not including the wool.  I have dumped it at this point, and anticipate continuing to empty it every oil change. 

 

 

 

[Local Apparent Friday]

The next 5k change, 10 since engine swap/catch can install.  Changing at 5k intervals despite running mobil 1 full syn high mileage, given that most of our miles are either towing or offroad boondocking.  Changed the wool out this time bc it was nasty compared to the first 5k.