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
