Diagnostic Help

[Harrison_Bergeron]

I installed a water separator oil catch can similar to this setup, it filled with oil very quickly, and I knew that I had severe blow by issues. I checked compression, it was very poor in three cylinders. While showing the car to a prospective buyer from 3geez today a few things happened that have me stumped.

1. The fluid in the catch can became milky, but the oil on the dipstick, and the oil visible through the oil cap are still clear.

2. The idle increased when I removed the oil cap while the engine was running.

What do these two things mean? Can they help pinpoint the cause of the blow by?(rings/cylinder scoring, head gasket, valve seals)

[1987AccordLx-i]

I installed a water separator oil catch can similar to this setup, it filled with oil very quickly, and I knew that I had severe blow by issues. I checked compression, it was very poor in three cylinders. While showing the car to a prospective buyer from 3geez today a few things happened that have me stumped.

1. The fluid in the catch can became milky, but the oil on the dipstick, and the oil visible through the oil cap are still clear.

2. The idle increased when I removed the oil cap while the engine was running.

What do these two things mean? Can they help pinpoint the cause of the blow by?(rings/cylinder scoring, head gasket, valve seals)

milky oil is associated with a blown head gasket... but if you have normal oil in the crankcase then something is not working right...

[2oodoor]

are you using a PVC valve in that set up? you cant run streight vacuum from the intake side, this will put moisture from the intake air into that reservior as well as suck oil right into it..(got milk>) its only supposed to relieve pressure from the crankcase in a metered fashion. If there happens to be blowby oil fumes on the back side of the pistons , not the combustion side, then that is what this thing is supposed to be collecting.

[Harrison_Bergeron]

I have the line from the pcv valve into a "T" with the line from the valve cover, both of those go to the separator, which then goes to the intake manifold where the valve cover vent used to be plumbed. Where the PCV went is capped.

Both lines went to a vacuum source from the factory.

[2oodoor]

If that is how you have it then you are not venting properly.
Why do you even have an alternative set up for this anyway? do you run boost?
Catch can set ups are to enhance the crankcase vent system because of the excess blow by created from combustion chamber pressures from boost.

The valve cover is where the vent gets fresh air, normally thru a hose in the air intake or you can just use a filter cap on that same grommet. Having vacuum there does nothing but make you loose vacuum.

The pvc should have solid strong vacuum at the valve, then the other end should go into your can, separator etcc. then that device should pull from the oil pan grommet. In other words pvc is a metered check valve that is in place in the "hose" or contained device that then sucks out "fumes" from the oil pan. Catch can just eliminates more solids from that sucked harvest air before it gets into the vacuum source.

[Harrison_Bergeron]

I think I understand what you are saying now, I thought that the hoses would still pull vacuum on either side of the throttle(just different amounts at different throttle positions), and the one on the manifold side was easier to plumb to.

I'm still confused though. I did the catch can setup because my air box had oil pooling in it that I attributed to excessive blow by pushing oil(vapor) into the intake. I am pretty confident that the oil is coming from the valve cover hose, which means the hose is not just sucking in, it is blowing out, which it sounds like you are saying is wrong. This was to be a band aid for that issue.

I think I see what I need to do to understand the problem better. I am going to re-plumb the system so that the catch can is just inline with the stock lines and their respective intake sources and see if that provides any new information.

[2oodoor]

simple set.. the PVC valve is a pre metered device that should be purchased per application
The PVC should be getting vaccum from the strongest vacuum source intake manifold

The PVC should be plumbed to the Black box or oil separator (wheather it is via a catch can or not)

The PVC "system" gets it's air from the vent grommet on the valve cover, note that I said air not vacuum.

If the PVC system components up to the tube going into the oil pan down there has any leaks, it will not properly vent the crankcase.

The valve cover part in a way of speakinghas nothing to do with the PVC in that it shares no components or plumbing.

The vent on the valve cover in a way of speakingis to prevent vacuum from building up in the crankcase so that it does not start sucking raw oil into the intake manifold.
The PVC system is in a way of speakingto prevent air pressure from building up in the crankcase.

[lostforawhile]

it's possible under certain vaccume conditions the pcv valve may not be creating a vaccume on the system, in this case a small amount of blowby may vent out the valve cover, but if oil is puddling there is a more serious problem. there's a small filter built into the original air cleaner if i remember right to stop any oil from ending up in the air cleaner it's not much of a filter though. I think this would mainly occur when manifold vaccume is at it's lowest. if there's no compression on three cylinders, chances are there could also be a very poor vaccume signal at the intake, and the pcv simply isn't working right. low compression also means low vaccume when pulling in the intake charge. have you hooked a vaccume gauge to manifold vaccume and seen what it reads?

[lostforawhile]

here you go http://www.classictruckshop.com/club...ts/vac/uum.htm

[InAccordance]

imo, pvc is one of those things that if it aint broke, dont fuck with it...
unless your running some serious mods or boost, just leave it alone.

[Civic Accord Honda]

catch cans sometimes get filled with milky stuff normally do to condensation same with under oil cap..

[lostforawhile]

imo, pvc is one of those things that if it aint broke, dont fuck with it...
unless your running some serious mods or boost, just leave it alone.

the catch can is an easy mod if you do it right, it just plumbs between the top of the box and the valve itself as long as there aren't leaks it's fine

[InAccordance]

oh i know, just saying there's really no point to it unless your running serious modifications.

[lostforawhile]

oh i know, just saying there's really no point to it unless your running serious modifications.

it keeps the blowby crap from coating the inside of your intake

[Harrison_Bergeron]

it keeps the blowby crap from coating the inside of your intake

Exactly, when I first got my car it would not run for more than a few seconds before stalling out and not starting. The only thing i did to get it running was spraying throttle body cleaner down into the manifold and scrubbing as far as I could down the throttle body. Now it starts first time every time, and has not stalled once.