Okay, so I have a 1998 EK hatch with a 98+ spec JDM B18C type R swap. I have some work done to it and I'm dynoing around 200whp. As many people know, the stock PCV systems on these motors aren't that great. Well, my stock PCV system started letting too much oil through, causing the car to smoke at times. This is even after I changed the PCV check valve a few times.

Because of this, I did some research and decided to get completely rid of the factory PCV system and mount my own crankcase ventilation system/oil catch can. I drew a picture to best-explain how I mounted the catch can, but I'll also try to describe it in words below as well.

I took the factory black PCV box completely off and put a BWR block plug in its spot to close the big hole up. I welded the nipple on the back of the block shut that a hose from the black box would originally run to. I unscrewed the two 14mm hex plugs on the back of the block, and installed two nipples from the Honda Prelude for crankcase ventilation. I teed these two nipples together with a t-fitting and ran them into the 'IN' on the catch can. I ran the 'OUT' from the catch can into the factory nipple on the intake manifold that the PCV check valve hose would normally run into.

Basically, what I thought I was doing was making my own PCV system, but instead of a check valve, I was using the catch can to baffle the oil and to recirculate only the air back into the intake manifold, with no oil.

Well, I went wrong somewhere. On start up, my car was bogging and chugging, and my garage filled with smoke within 30 seconds to a minute. I unscrewed the catch can and it was filled with oil. I took my intake off and cracked the throttle body - it was coated on the inside with oil. Oil was making it through the lines that I routed into the catch can, and going back out of the catch can into the intake manifold and getting burnt out of the exhaust - and a TON of oil at that.

Where did I go wrong? Why did all of this happen. I'm assuming that I routed something wrong, or hooked something up in the wrong place, but I'm not sure what.

Can somebody please help me and explain to me what I've done wrong?

Attached is the picture that I drew to explain everything.



Thank you so much in advance!

- DJ

 

Your mistake was eliminating the PCV valve. When you have a closed loop PCV system, you must have the one-way valve. The check valve doesn't keep oil from the manifold, it acts as a specifically sized restriction. Without the PCV valve you now have a major vacuum leak.

This one has instructions for a closed loop or open system. It also has an extra hose that drains the oil back to the block.



BTW: Why did you weld that small nipple closed. You could have just capped it off.

 

If you wanted to simply add more oil separating capability, you could just plumb a good air line filter/dryer into the hose between the stock PCV valve and the manifold nipple (leave the PCV valve in place of course)...



For $25 it works great. I plumbed one into my wife's Honda Pilot and it now catches all the oil in the PCV line.

DIY Oil Catch-Can for PCV system - Honda Pilot - Honda Pilot Forums

Red is from the PCV valve, and green is too the manifold nipple:

 

If I had a major vacuum leak, then would the idle not sky rocket? What exactly is causing the vacuum leak? How does everybody else eliminate the entire PCV system and run a catch can?

 

When "everyone" else runs a catch can, they typically vent it to the atmosphere with a filter on top of the can. Then they cap the nipple on the manifold. If you want a closed system that flows the fumes into your intake manifold (like OEM), you have to use a PCV valve.

As for why they idle is not skyrocketting, it could be due to the fact your trying to pull vacuum on the crankcase.

 

So, would my fix be as simple as to put the check valve in between the catch can outlet and the intake manifold?

 

That is the first thing I would try.

 

I would have capped off the manifold nipple and ran the drain back hose to factory drain back nipple instead of welding it shut. Sounds like now you draining oil right back into your airflow through the head going into the cylinders and burning it off as it exits through the exhaust causing smoking