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yup
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Discussion Starter · #1 · (Edited)
Rerouting PCV Hoses to Reduce Oil in Blowby Gasses.


I was having trouble with oil collecting in my intake. It was enough to create a small run of oil running towards the throttle body where it collected and made a mess of the throttle plate.

I discovered that the hose coming from the valve cover was the culprit. This hose carries blowby gasses from the head and block to the intake so that the gasses are burnt in the cylinders.

After some research on www.sr20deforum.com, I read that Mike Kojima rerouted this hose so that it passed through the oem oil catch can. The catch can is one of the two black containers on the front of the sr20de (the one closer to the vavle cover) and it seperates oil from the blowby gasses and returns oil to the oil pan.

The following is a write up showing how to complete this modification. At the time I was also installing the intake piping kit that I bought off of ebay. However, you can still reroute your pcv hoses even if your are using the oem intake or an aftermaket cai or wai.





This is the oem pcv routing, In the first picture... you can see the thick black tubing that runs inbetween the valve cover and the distributor. This tubing comes from the oil catch can in the front of the engine. The oil catch can is the rusty silver box (it used to be painted black) between the valve cover and the furthermost black box (the one with the little breather filter on it). The other end of the tubing runs under the ignition wires and to the metal t piece that sticks out from the side of the valve cover. You can see this t piece in the second picture above the red/orange wire cap. (The hose that runs from the t piece to the intake has been romoved in this pic.) This t piece is where the oil problem originates. Because the t piece directly connects the valve cover blowby gasses to the intake there is nothing that will filter the oil out of the blow by gasses. The way to correct this problem is by rerouting the blowby gasses from the valve cover to the oil catch can in the front and then from the catch can to the intake. This way the oil catch can will filter the oil out of the valve cover blow by gasses.





In order to use the oem catch can to filter the valve cover blowby gasses we must understand the flow of the blowby gasses. Above is a diagram of the rerouted blowby hoses. As you can see, the hose from the t piece no longer goes directly to the intake piping. Rather it is rerouted to beneath the oil catch can. In order to do this one must install a t piece below the oil catch can. In addition the cleaned blowby gas coming from the top of the oil catch can must be rerouted to go directly to the intake piping instead of to the t piece on the valve cover, which is the factory routing.






Let's look at the catch can. The top picture above shows the bottom of the catch can at the top of the picture with a hose connector sticking out the bottom. Directly below this we can see the connector that is sticking out from the block. The bottom picture shows the hose that joins these two connectors. Notice that it has a small heat shield on the hose.

This reminds me to mention that the hosing that you use must be emission type hosing, rather than heater hose. The emissions hosing will withstand the oil that passes through it and will not deteriorate in a few months like heater hose will. Even the t piece that we will use needs to be emissions grade. Regular plastic will either melt or deteriorate over time and you don't want pieces of plastic swimming in your engine oil.

But back to the subject. The hose that joins the two connectors serves two purposes. The first is to allow blowby gas to flow out of the block and up in the oil catch can, where the oil will be seperated. The second purpose is to allow the collected oil to drain back into the block. Unlike the setup of certain aftermarket catch cans that will slowly collect oil and must be checked every so often, the oem catch can system recylces the oil to the block. This is the reason why I did not want to use an aftermarket catch can, even though they can be quite pretty. ; )










The top picture above shows the three hoses that I used to reroute the blowby gasses. The smallest hose is the blowby hose that I installed the t piece into, so that the valve cover blowby gasses would run through the oil catch can. As you can see, I managed to scavenge bends and connectors that were already being used in this system and some from the stock intake tubing that I had removed. The advantage of reusing the oem connectors is that they are made of metal and will not deteriorate like plastic connectors will. The lower picture shows the blowby bend with t piece installed under the catch can. You may notice that the t piece pictured is a heater hose plastic connector. I later went back and replaced this connector with an emissions grade connector that was a hard rubber. The hose comming from the valve cover will be connected to the open end of the t piece in the second picture above.



Here you can see the rerouting that was done ontop of the engine. Notice that one end of the vlave cover t piece was capped off and the zip tied for safety. The other connection on the t piece was ran under the ignition wires and down to the t piece that we installed under the catch can. This is the only piece of emissions tubing that I needed to purchase. All of the other hoses were salvaged from the original blowby hoses. Also note that the hose that comes from the oil catch can runs directly into the intake piping. This means that all of the blow by gas that reaches the intake piping will have filtered through the catch can. Also, the upward bend coming off of the catch can will aid in returning collected oil to the catch can and therefore to the block. The supplies that I used to complete this project are shown below. The intake piping and the small hose in the purple packaging are only needed if you are installing the ebay intake on an SR20DE highport engine. The two items in red packaging will be needed to complete the blowby gas rerouting. One is a length of emissions tubing. The other is the T piece that is installed under the oil catch can. For reference, I later used an emissions t piece made by the same company (HELP!) part number 47072. With the rerouted blowby gas hosing, I have noticed that there is much less oil accumulating on the throttle plate and in the intake other the past year and that oil consumption has gone down. A cheap and effective mod in my opinion.



Completed
 

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now on the West side!
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Re: stock oil seperator rerouting

Great writeup! I will be doing this later this week on my turbo SE-R because I recently saw how much oil really does blow by into the intake right before the turbo :( Its not a terrible amount, but its gross!
 

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yup
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Discussion Starter · #4 · (Edited)
Re: stock oil seperator rerouting

Thanks... I hope the pictures aren't too huge. I wasn't sure whether to put a 56k warning in the title.

I eventually got around to replacing the crappy blue ebay tubing (since it wasn't emmisions grade and it began to get hard). I also sanded and painted the rusty oil seperator with some nice black semigloss high temp engine paint. You can see it in the picture below.

 

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yup
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Discussion Starter · #7 ·
thanks guys... i just happened to have a little vinyl cap in the garage that fit perfectly. wouldn't know where to buy one individually or even a pack. heck i dont even know what it was for in the first place.
 

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Tired!
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When looking at that, isn't it the same as routing the lower block fitting to the T on the valve cover, then taking the other nipple of the T and running it to a catch can? Both ways the catch can runs back to the intake pipe. Just seems like it is the same and would work for those of us with an aftermarket oil catch can.

Brent
 

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yup
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Discussion Starter · #9 ·
coach said:
When looking at that, isn't it the same as routing the lower block fitting to the T on the valve cover, then taking the other nipple of the T and running it to a catch can? Both ways the catch can runs back to the intake pipe. Just seems like it is the same and would work for those of us with an aftermarket oil catch can.

Brent
Yes that is one way to route a catchcan and it would work just fine. However, there are some benifits to the routing that i described. The biggest benifit is that nothing needs to be emptied. Aftermarket catchcans collect oil over time and need to be emptied where as the stock oil seperator takes the oil and returns it to the block. The way i've routed the blowbygasses keeps this feature of the oem system. The other benifit is that most of us already have the stock oil seperator and can do this mod for a few bucks versus buying a new catch can.

But you're right there isn't a big difference between the two routings. I just enjoy the benifits of the way i've routed the system.
 

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change isn't always good
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nj20de said:
Yes that is one way to route a catchcan and it would work just fine. However, there are some benifits to the routing that i described. The biggest benifit is that nothing needs to be emptied. Aftermarket catchcans collect oil over time and need to be emptied where as the stock oil seperator takes the oil and returns it to the block. The way i've routed the blowbygasses keeps this feature of the oem system. The other benifit is that most of us already have the stock oil seperator and can do this mod for a few bucks versus buying a new catch can.

But you're right there isn't a big difference between the two routings. I just enjoy the benifits of the way i've routed the system.
I am bringing this one back from the dead. I have a question?!? Can I run this set up but instead of tapping back into the intake with the "clean blow by gasses" can I just vent it into the air? What would be the advantage/disadvantages to putting the gasses back into your engine? What are the advantages/disadvantages of venting into the air?

Right now I have the oil seperator hooked up the stock way except the line coming off the tee on the valve cover (the one that points toward the driver fender) is just vented into the air. It gets a slight build up of oil on it though and figured if I reroute the way posted above and then vent from the top of the catch can I shouldn't get any oil build up at all! Someone please proove me right or wrong. In the past I have had losing oil problems and every little bit that I can keep in the engine the better!!!!
 

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OMFG WTF BBQ
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The problem with venting to the atmosphere, in a DE, a DET, a DE+T or any MAF equiped vehicle is that you're venting metered air - air that has been counted by the MAF, and therefore has fuel allocated for it, so if you don't feed it back in, you can run rich, or even in a vacuum circumstance, run lean from sucking air into the system.

I have discovered:

Sometimes recirculation is redundant retarded emissions, sometimes it's absolutely vital to having a well tuned, efficient engine. For power, for heat efficiency, for engine longevity and for fuel economy. it's universally relevant.
 

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Drive it like ya stole it
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G20.net stray
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Ive got a question!
Ive got a turbo, and have done this re-route, but ive noticed most of my oil is coming in through the PCV valve on the top of the valve cover (the fitting that sticks out of the top towards the cabin and goes into the plenum directly- before anyone asks, i just replaced it). Every time I take that hose off, there is oil all over the inside and it is running down the first 2 chambers of the plenum (passenger side). Should I just cap this off, or re-route it to hook up with these other hoses?
 

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Pâté Performance...
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Will the seperator ever fill up with oil?
 

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change isn't always good
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Will the seperator ever fill up with oil?
I don't know if mine filled up but there was oil marks all around the hose on it. I just put new hoses on and blew out the seperator and it fixed the problem. I think my problem was that I had that little brush thing that is suppose to be on the air intake side on the seperator side. This probably caused my back up. Just periodically change the hoses and clean the seperator and you should be fine.
 

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yup
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Discussion Starter · #16 ·
freaktroll said:
Ive got a question!
Ive got a turbo, and have done this re-route, but ive noticed most of my oil is coming in through the PCV valve on the top of the valve cover (the fitting that sticks out of the top towards the cabin and goes into the plenum directly- before anyone asks, i just replaced it). Every time I take that hose off, there is oil all over the inside and it is running down the first 2 chambers of the plenum (passenger side). Should I just cap this off, or re-route it to hook up with these other hoses?
sounds to me like you pcv valve is not working... luckily its a cheap part and easy part to replace.... you can check your valve by trying to blow air through the end that is screwed into the valve cover... no air should leak through. then blow through the other end and air should blow through. it sound like the check ball in your pcv valve just isnt preventing the oily air from leaking out of the valve cover
 

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yup
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Discussion Starter · #17 ·
robkris8079 said:
I don't know if mine filled up but there was oil marks all around the hose on it. I just put new hoses on and blew out the seperator and it fixed the problem. I think my problem was that I had that little brush thing that is suppose to be on the air intake side on the seperator side. This probably caused my back up. Just periodically change the hoses and clean the seperator and you should be fine.
the stock oil seperator does not fill up because there is a hole in the bottom of it that is routed with a hose back into the engine block... this way all the oil that is collected will drain back down into the oil pan.
 

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HATER
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ike rocks

time for me to contribute once again. on my "jdm" uk89j motor, and i believe all jdm motors the oil seperator is a little different, i ended up having to cut off about 2 inches of the tube the drops into the block to get a threeway going on. but i think everyone will sacrafice a little to get a threeway. i also used the other option from the valve cover and i think it makes it look more "stock"

ok enough of this crap, on with the oversized pictures.



 

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Drive it like ya stole it
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you and your sodium filled valves....that looks sweet btw, nice job. What kinda car is this in the pictures? Got any pictures of the color of the car??? I like it!
 

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nx-less
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cause4alarm: where did you find the plug to cap off the T at the valve cover and emissions grade Tee adapter? i went to a local winchester auto and pepboys, but they only had heater grade (plastic) so even when i cut the lower tube down, i wasnt able to get the 3-way to fit.
 
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