Catch cans

[hgeranium]

I have a quick question for those with catch cans installed or with knowledge on how they should fit. I'm wanting to hook up a catch can to my CCV hose to eliminate any possibility of oil dripping on the air filter. I have the hose disconnected and letting it vent and drip wherever. Better it smell bad then replace the air filter. I am thinking of going with a catch can like this: 

Question 1: What will be the best way to route this? Should I go from a) CCV -> inlet side then outlet side -> airbox? Or should I just have it b) go from CCV -> inlet? This particular kit has a little breather filter that goes on the top. I'm not sure which would be more efficacious to my goal or if the former option would still lead to oil coming through the air box but more slowly. There are also other kits that have the option to place steel wool inside the baffle to better hold the debris. This kit in particular doesn't seem to have that so I'm wondering if I can still put in steel wool or it's just a baffle. I'd rather spend a little extra money than save a little for the option to replace the filter element myself. The more expensive ones usually have a petcock to drain the fluid which would certainly justify the price in itself anyways.

 

Question 2: If I go with the latter routing option, what is the best way to deal with the outlet port? Since it's already breathing up top, can I just put in a threaded plug? Or do I need to put in a tap and filter on that as well? It feels redundant at that point but I have no experience with these and would rather be sure.

 

[ghetdjc320]

I’m curious what issue you are currently experiencing? I run catch cans on high performance marine engines but that is simply because such engines have more blow by than most along with intercoolers that would loose efficiency if coated in oil. But in a 4.0, unless the vent system on you valve cover isn’t working properly (which is a serious possibility), I’ve almost never seen a single drop of oil in that tube. 
 

Kind of ironic too that we used to dip air filters in motor oil to improve the filtration of fine particles and prevent the top ends from rusting prematurely 

[hgeranium]

1 hour ago, ghetdjc320 said:

I’m curious what issue you are currently experiencing? I run catch cans on high performance marine engines but that is simply because such engines have more blow by than most along with intercoolers that would loose efficiency if coated in oil. But in a 4.0, unless the vent system on you valve cover isn’t working properly (which is a serious possibility), I’ve almost never seen a single drop of oil in that tube. 
 

Kind of ironic too that we used to dip air filters in motor oil to improve the filtration of fine particles and prevent the top ends from rusting prematurely 

Set up normally, the CCV to airbox in renix 4.0s almost always lead to tons of oil in the air box. Cruiser made a fix in the book here regarding it but I've heard it's not a bulletproof solution, so I'd rather do the catch can and not worry about it. I was having to replace my air filter every month or two because of it when I first got the truck. Especially being at 190k my blowby is surely higher than normal

[pizzaman09]

So I was going down the route you are proposing, I even purchased the exact catch came you have in the photo above.  However before doing that I decided to increase the vacuum on my crank case by drilling out the restrictor orifice and running a 1/4" diameter line between it and the intake.  

This upgrade has completely fix my oil leaks, and has not effected idle.

[75sv1]

I run two on my Chevy Avalanche. I run a Radiant and another, UMD ???. I do catch some oil. Maybe a teaspoon every 500 miles. I run about 10:1 compression, with 88 octane. If a higher compression, then possibly run a catch can. 

    On the 4.0L, most run the catch can on the rear CCV tube. If oil in the air filter, then its either the rear CCV tube needs upgrade to 97+ or its blocked up with crude. On mine, I used the FlePro rubber gasket.  Upgraded to a 93-95 CG valve cover. 

[llhat]

2 hours ago, pizzaman09 said:

So I was going down the route you are proposing, I even purchased the exact catch came you have in the photo above.  However before doing that I decided to increase the vacuum on my crank case by drilling out the restrictor orifice and running a 1/4" diameter line between it and the intake.  

This upgrade has completely fix my oil leaks, and has not effected idle.

care to expand more on this?   did you do a write up? 

[Eagle_SX4]

I thought I had some serious blowby on the 4.0 in my Eagle but turns out I didn't have vacuum on the rear orifice. My air filter has been dry since I fixed that issue. Check to make sure you have vacuum through the rear orifice they like to get clogged with sludge.

[hgeranium]

1 hour ago, Eagle_SX4 said:

I thought I had some serious blowby on the 4.0 in my Eagle but turns out I didn't have vacuum on the rear orifice. My air filter has been dry since I fixed that issue. Check to make sure you have vacuum through the rear orifice they like to get clogged with sludge.

That’s what I thought at first too but I definitely do have vacuum. I’ve got a brand new grommet and hose on there.

3 hours ago, pizzaman09 said:

So I was going down the route you are proposing, I even purchased the exact catch came you have in the photo above.  However before doing that I decided to increase the vacuum on my crank case by drilling out the restrictor orifice and running a 1/4" diameter line between it and the intake.  

This upgrade has completely fix my oil leaks, and has not effected idle.

Like llhat said: you’re saying you drilled out the rear PCV grommet’s hole? And doing that the CCV hose going to the air filter is no longer dripping oil? 

[hgeranium]

2 hours ago, 75sv1 said:

I run two on my Chevy Avalanche. I run a Radiant and another, UMD ???. I do catch some oil. Maybe a teaspoon every 500 miles. I run about 10:1 compression, with 88 octane. If a higher compression, then possibly run a catch can. 

    On the 4.0L, most run the catch can on the rear CCV tube. If oil in the air filter, then its either the rear CCV tube needs upgrade to 97+ or its blocked up with crude. On mine, I used the FlePro rubber gasket.  Upgraded to a 93-95 CG valve cover. 

Probably a dumb question but you need to upgrade to a new VC to run the 97+ PCV setup? Does it just allow for more vacuum  like pizzaman’s solution is doing?

[75sv1]

1 hour ago, hgeranium said:

Probably a dumb question but you need to upgrade to a new VC to run the 97+ PCV setup? Does it just allow for more vacuum  like pizzaman’s solution is doing?

What I did, is initially upgraded to a '91-95 HO VC. It allowed a larger hose. You also need to the 97+ fitting to the intake manifold. The 93-95 GC (Grand Cherokee) has the CCV fitting of the latter 97-up steel VCs. I did do the Cruiser 'upgrade' to them. The 91--95 HO VCs and the 93-95 GC VC have the aluminum inner towers. 

      Another possibly 'solution' is to put on a 'breather' to the front hole of the VC. Thus the air filter box won't be sucking air and oil into the filter. Some use a hose to space the breather a bit from the VC. 

  Also, you can use RTV in place of the VC gasket. 

[hgeranium]

7 minutes ago, 75sv1 said:

What I did, is initially upgraded to a '91-95 HO VC. It allowed a larger hose. You also need to the 97+ fitting to the intake manifold. The 93-95 GC (Grand Cherokee) has the CCV fitting of the latter 97-up steel VCs. I did do the Cruiser 'upgrade' to them. The 91--95 HO VCs and the 93-95 GC VC have the aluminum inner towers. 

      Another possibly 'solution' is to put on a 'breather' to the front hole of the VC. Thus the air filter box won't be sucking air and oil into the filter. Some use a hose to space the breather a bit from the VC. 

  Also, you can use RTV in place of the VC gasket. 

I think I’ve seen what you’re talking about with the breather on the forum before. I do wonder if it’s worth it to keep the CCV attached to the airbox to cut down on the smell. The dripping doesn’t bother me but letting it vent into the atmosphere is a smell I’m not a huge fan of. I imagine having the breather would stop the oil but still cause the crank case smell to come out. 

[pizzaman09]

7 hours ago, llhat said:

care to expand more on this?   did you do a write up? 

I do need to do a write up, but in short, I took the white plastic restrictor orifice in the rear of the RENIX valve cover and drilled it out to the largest diameter I could fit.  Then I took a 1/4" diameter vinyl tube and ran it from the white plastic orifice piece to the intake manifold port, both of which are the right diameter on the OD for the 1/4" tube.  It flows substantially more vacuum.

[TheNerfsmith]

This might be a dumb question but did the 4.0 change the valve cover design? Will the HO ones not fit on a Renix?

[Eagle_SX4]

4 minutes ago, TheNerfsmith said:

This might be a dumb question but did the 4.0 change the valve cover design? Will the HO ones not fit on a Renix?

There are a few different versions of the 4.0 valve cover and there are differences between what model it is from (Cherokee, Grand Cherokee, or Wrangler) but any 4.0 valve cover will bolt on to any 4.0 engine. You will just have to change the breather/CCV hoses to fit the valve cover you choose.

[hgeranium]

18 minutes ago, pizzaman09 said:

I do need to do a write up, but in short, I took the white plastic restrictor orifice in the rear of the RENIX valve cover and drilled it out to the largest diameter I could fit.  Then I took a 1/4" diameter vinyl tube and ran it from the white plastic orifice piece to the intake manifold port, both of which are the right diameter on the OD for the 1/4" tube.  It flows substantially more vacuum.

Do you have a picture of this plastic orifice? I have the rubber grommet that the PCV hose plugs into that goes between there and the intake. Is the plastic orifice you’re mentioning a part of the hose? Or do you have an HO or newer VC?

[pizzaman09]

27 minutes ago, hgeranium said:

Do you have a picture of this plastic orifice? I have the rubber grommet that the PCV hose plugs into that goes between there and the intake. Is the plastic orifice you’re mentioning a part of the hose? Or do you have an HO or newer VC?

This is the best picture I have on me.  I'm on a work trip and won't have availability to the truck until next week to get better photos.

I think the white plastic piece comes pressed into the end of the factory plastic tube.  It pulls off easily.

[llhat]

4 hours ago, pizzaman09 said:

This is the best picture I have on me.  I'm on a work trip and won't have availability to the truck until next week to get better photos.

I think the white plastic piece comes pressed into the end of the factory plastic tube.  It pulls off easily.

ok, I can see the larger OD hose...   and seems like a doable thing.

 

i thought though the restriction was in the grommet and not in the hose ( white 'nipple)

 

I'd also guess you did not change the nipple screwed into the intake manifold?

IIRC the HO change-over  utilized a larger nipple on the intake, as well as an even larger hose.

 

I've been on a process of cleaning my 'original' design hose with more frequency... instead of each oil change.

 

 

[pizzaman09]

27 minutes ago, llhat said:

ok, I can see the larger OD hose...   and seems like a doable thing.

 

i thought though the restriction was in the grommet and not in the hose ( white 'nipple)

 

I'd also guess you did not change the nipple screwed into the intake manifold?

IIRC the HO change-over  utilized a larger nipple on the intake, as well as an even larger hose.

 

I've been on a process of cleaning my 'original' design hose with more frequency... instead of each oil change.

 

 

The orifice piece in the rear grommet just pulls out, shouldn't take too much effort, it is a lightly fit barbed fitting.  I did not change out the fitting in the manifold.  For both the valve cover and intake side, the original molded plastic pipe was small in diameter and slid into the fittings as the fittings were designed as a female connection for the small tube.  It turns out the OD of both fittings are perfect for a 1/4" diameter tube to fit over them.

[hgeranium]

2 hours ago, pizzaman09 said:

The orifice piece in the rear grommet just pulls out, shouldn't take too much effort, it is a lightly fit barbed fitting.  I did not change out the fitting in the manifold.  For both the valve cover and intake side, the original molded plastic pipe was small in diameter and slid into the fittings as the fittings were designed as a female connection for the small tube.  It turns out the OD of both fittings are perfect for a 1/4" diameter tube to fit over them.

I see exactly what you're talking about now. Great idea! I will try that next time I'm in a place to get some tubing