Cheaper Jeeper
Full Access Member
My old F250 has had a bit of a blowby problem as long as I've had it. Part of it is the actual quantity of blowby gases and at least part of it is probably due to the fact that with the Banks tubo kit, the CDR never sees much vacuum.
So, I decided it needed an oil trap. I decided to make the body of it out of 4" PVC and the body of the unit is threaded so that the bottom half screws off to allow you to dump the trapped oil back into the crank case. This removeable collection chamber has about a 1 quart capacity. I initially built the unit with 1/2" inlet and outlet tubes, and unfortunately, this resulted in excessive backpressure and the engine started puking oil out of the dipstick tube.
So I went back to the drawing board and enlarged the inlet and outlet tubes to 3/4". The original design included a 90 degree elbow inside on the inlet tube inside the main chamber to aim the vapor stream at the inside wall of the oil trap chamber. The idea was that the oil vapor colliding with the wall of the chamber would cause it to condense and then collect in the bottom of the chamber. While this resolved the backpressure issue, it didn't trap much oil.
So, I got rid of the inlet elbow that aimed the vapor stream towards the inside wall of the chamber and replaced it with a straight pipe that went down to within 1-1/2" of the bottom of the chamber. Then I got some very coarse steel wool (# 4 size) at the hardware store and stuffed a bunch of it into the upper part of the main body so that the oil vapor would have to pass through it to get to the outlet.
So far I've only driven it one day to work and back (about 50 miles). No backpressure issues or oil puking out of the dipstick tube. When I screwed off the collection chamber (after letting it sit overnight) and looked inside, LO AND BEHOLD! It had about 1/4" of oil in the bottom! At least 3 or 4 ounces.
In terms of how much it is trapping, the installation of this new design just HAPPENED to coincide with my failing an emmissions test. It blew a 59% on the opacity test without the oil trap (the limit is 55%) and failed. After installing the oil trap I ran it through again the next day and it blew a 43% on the opacity test and it PASSED!
Before installing the oil trap it was burning through a quart of oil every 200 miles or so. On a 50 mile trip that would be about 8 ounces. Since the trap had about half that much in it, and my exhaust opacity results were reduced by over 25%, it looks like this oil trap has reduced my oil consumption by around 50%. Since some of the oil consumption is undoubtedly oil getting into the cylinder past the rings and past the valve guide seals (which I'm convinced are shot) I think its pretty safe to say that the oil trap is catching nearly all the blowby oil that was going into the intake. Before it blew a big blue cloud of smoke every time I stepped on the throttle. Now it almost never blows any blue smoke and I can actually see the black smoke it makes when pulling hard!
Since my main concerns were the amount of oil vapor going through the turbo, and the fact that oil into the intake concentrates in the back two cylinders (causing them to overheat and develop head gasket leaks), I'm really happy with the results. I can handle it burning a quart every 300-500 miles as long as it isn't killing my turbo or eroding my headgaskets...
So, I decided it needed an oil trap. I decided to make the body of it out of 4" PVC and the body of the unit is threaded so that the bottom half screws off to allow you to dump the trapped oil back into the crank case. This removeable collection chamber has about a 1 quart capacity. I initially built the unit with 1/2" inlet and outlet tubes, and unfortunately, this resulted in excessive backpressure and the engine started puking oil out of the dipstick tube.
So I went back to the drawing board and enlarged the inlet and outlet tubes to 3/4". The original design included a 90 degree elbow inside on the inlet tube inside the main chamber to aim the vapor stream at the inside wall of the oil trap chamber. The idea was that the oil vapor colliding with the wall of the chamber would cause it to condense and then collect in the bottom of the chamber. While this resolved the backpressure issue, it didn't trap much oil.
So, I got rid of the inlet elbow that aimed the vapor stream towards the inside wall of the chamber and replaced it with a straight pipe that went down to within 1-1/2" of the bottom of the chamber. Then I got some very coarse steel wool (# 4 size) at the hardware store and stuffed a bunch of it into the upper part of the main body so that the oil vapor would have to pass through it to get to the outlet.
So far I've only driven it one day to work and back (about 50 miles). No backpressure issues or oil puking out of the dipstick tube. When I screwed off the collection chamber (after letting it sit overnight) and looked inside, LO AND BEHOLD! It had about 1/4" of oil in the bottom! At least 3 or 4 ounces.
In terms of how much it is trapping, the installation of this new design just HAPPENED to coincide with my failing an emmissions test. It blew a 59% on the opacity test without the oil trap (the limit is 55%) and failed. After installing the oil trap I ran it through again the next day and it blew a 43% on the opacity test and it PASSED!
Before installing the oil trap it was burning through a quart of oil every 200 miles or so. On a 50 mile trip that would be about 8 ounces. Since the trap had about half that much in it, and my exhaust opacity results were reduced by over 25%, it looks like this oil trap has reduced my oil consumption by around 50%. Since some of the oil consumption is undoubtedly oil getting into the cylinder past the rings and past the valve guide seals (which I'm convinced are shot) I think its pretty safe to say that the oil trap is catching nearly all the blowby oil that was going into the intake. Before it blew a big blue cloud of smoke every time I stepped on the throttle. Now it almost never blows any blue smoke and I can actually see the black smoke it makes when pulling hard!
Since my main concerns were the amount of oil vapor going through the turbo, and the fact that oil into the intake concentrates in the back two cylinders (causing them to overheat and develop head gasket leaks), I'm really happy with the results. I can handle it burning a quart every 300-500 miles as long as it isn't killing my turbo or eroding my headgaskets...
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