JKU Oil Catch Can

[BlackKnight]

So I have been dropping oil, a lot of oil. It's not coming out of the tailpipe (emissions past with no issues). and we are talking about 1 quart every 2K miles. According to the Stealership, that's normal!?!?!

So I'm reading through the internets and discover this thing called an oil catch can. and thinking that that is where my oil has been going. So watching YouTube and reading up a little about the PCV system, I decided to pull the intake and take a look on the other side.

So I pull the throttle body and low and behold on the other side in the intake manifold are almost pools of oil. Apparently, the PCV has been sending all the oil I'm missing through the intake into the top end "to Burn off". Well, thinking that this amount of oil is actually not within specs I decided to run an oil catch can.

Checking out the interwebs there are direct bolt-on catch cans for JK 3.6ltr. but the Mishimoto one runs $180, and others make with brackets and hoses precut and "engineered" for the engine are around the same price.

So after watching a couple more videos (JK Gear and Gadgets), find out on amazon a $29 catch can of good quality. and decide to do it myself.

First up was picking up a 1"x1/4"x3' piece of flat aluminum stock from Lowes to make a bracket. Decided on the place to mount (off one of the bolts from the ECU.



The hole on the ECU side needs to be a 15/64ths bit, and the tab has to be no more than 1.5-2" as it would contact the cooling fins of the ECU. then after the 90* bend it should go about 3-5" to another 90* bend down to mount the catch can. The bolts that come with the can for mounting need a 13/64ths bit. (see above for the bend shapes).

Taking off the ECU bolt is an 8mm socket, then you can mount the can.


Next up is cutting into the PCV hardline. The easiest and cleanest way to do so is a pipe cutter.


And make sure you're cutting the correct line. you're looking for the one that connects to the intake just after the Throttle body.



There is a stack of three lines on the left (passenger side) of the intake. you are looking for the bottom one. (I then moved the middle to the bottom to get it out of the way, and the top went back in place afterward.



Once cut you have to take 5/8ths heavy radiator hose, got mine from Autozone. (make sure it's compatible with oil and solvents).



You have to make sure the hose alignment is correct or the baffling in the can will not work properly. The canister has in and out ports marked, and the Inlet comes from the PCV, the out goes to the intake.



My outlet was routed across the back of the engine (on the other side of the padding for the cover) and the inlet was the best path was from the left side, under the intake and looping back to the inlet side. I may change that loop to behind the engine at one point but was too tough to get to the back of the hard-line from the PCV before it turned forward.





So, now that that's done, I'm going to run some Seafoam spray through the intake, Oil, and fuel to start cleaning up what is in there. I Will keep a close eye out on the catch can (the nice thing is it has a dipstick ). I just passed 111842 miles on the odometer, so will pull it after 1000 miles and see what we have, and let you all know if it was worth the effort.

All in all, the cost of the DIY setup was maybe $50. A hell of a lot cheaper than the alternatives (Mishimoto, UPR Products)

[pirahnah3]

I ran one of those on my challenger and on that car it seemed to run about every oil change, but diff motor diff uses. Either way I am NOT a fan of reburning this stuff, yes it works and doesnt seem to cause any extra headaches and passes standards just not what I would think is the best way to manage it.

[BlackKnight]

Either way I am NOT a fan of reburning this stuff, yes it works and doesnt seem to cause any extra headaches and passes standards just not what I would think is the best way to manage it.

I Agree, definitely not a good design, but I understand why. Back in our old cars, we just vented the crankcase direct to the atmosphere (the old filters mounted directly on the valve covers were the first iteration of filtering the vented material). So designing it to re-enter the engine to be burned I understand. But with how much engine oil goes missing in my 111K engine, which according to the Stealership is normal, I think is WAY too much. Finding literally pools of oil in the intake tells me that as my engine has gotten older and worn in, my rings are letting a lot of blow-by pass into the crankcase.

I also know why they designed them, as is, Oil catch cans become a maintenance issue. They have to be emptied on a regular basis, and unless you make a gallon jug one, it's every couple thousand miles. Knowing that many vehicle buyers don't actually do the required maintenance, the engine designers decided to run it into the intake to be burnt rather than into a catch can.

That said, as Jeepers, WE have a tendency to work on our own rigs, follow or exceed maintenance requirements, as we want our jeeps to last forever, or at least until we beat them into submission and make a voluntary decision to replace/build something new (Or Old).

[Jonas]

I had no idea. I have been referring to my diesel truck as an oil burner seems the Jeeps aren't far behind.

[BlackKnight]

I had no idea. I have been referring to my diesel truck as an oil burner seems the Jeeps aren't far behind.

Yep, Acording to my Stealership 1 qt per 2K miles is normal burn through... Begining to think I'm running on the stuff...

[Car Jack]

Some fun, useless trivia. Back in the old days (think flathead Fords), the vent for oil vapor went to a tube that was routed down near the transmission, then down to drain onto the road. That's why old movies showing the road had this dark black stripe down the middle of each lane. I used to own a 51 Ford pickup project and was perplexed as to what this tube was going back to the transmission, then just being open to the atmosphere.

Anyways, nice work. I've done something similar, but it consisted of simply whatever hose I had around the garage and a 2L diet pepsi bottle.

[BlackKnight]

Some fun, useless trivia.

I'm a child of the 70s, where the vents were just on the top of the valve covers. I remember working in my uncle's garage each some and saw a Chevelle SS I was working on for the summer, taking it apart and rebuilding it. Before starting I saw that the vents on the valve cover were saturated. He explained that it was because the engine had a lot of wear and a lot of blow-by was building pressure and sending oil out the vent. so that was the first time anyone explained how it worked to me.

[MDSRACING398]

Explain to me how worn rings causes this?

[Modeler]

During the power stroke some of the gases escape past the rings into the crankcase, this pressure has to go somewhere and works its way up into the valve covers. Oil picked up by the gases goes out through the PCV valve to get burned. Worn rings, more pressure, more oil pushed into the intake system.

[BlackKnight]

During the power stroke some of the gases escape past the rings into the crankcase, this pressure has to go somewhere and works its way up into the valve covers. Oil picked up by the gases goes out through the PCV valve to get burned. Worn rings, more pressure, more oil pushed into the intake system.

This...

Modeler beat me to it...

[MDSRACING398]

There is plenty of crankcase pressure just from down stroke. I will agree may be more on a worn engine but There is plenty of oil in the valve covers on a good engine.. I have catch cans on my buggy because even on off camber oil comes out breathers and it makes a real mess on rollovers. If your rings are worn bad oil goes out the exhaust too. Just remember the more restrictions on the venting system the more leaks you are going to create elsewhere. The pressure needs to go somewhere with added restriction seals start leaking.

[BlackKnight]

The pressure needs to go somewhere with added restriction seals start leaking.

The canister I picked up has Baffles, not the Brass micro filter that many of them have. Wanted to make sure I was not putting too much restriction, just for that reason.

Bob

[Modeler]

There is plenty of crankcase pressure just from down stroke. I will agree may be more on a worn engine but There is plenty of oil in the valve covers on a good engine.. I have catch cans on my buggy because even on off camber oil comes out breathers and it makes a real mess on rollovers. If your rings are worn bad oil goes out the exhaust too. Just remember the more restrictions on the venting system the more leaks you are going to create elsewhere. The pressure needs to go somewhere with added restriction seals start leaking.

But, for every downstroke there is a corresponding upstroke on another cylinder negating that pressure.