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Oil Separator Diagnosis

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I have read and reread all the posts I could find regarding the external oil separator and I still am not sure if mine is good or bad. I have a 97 boxster with a vertical oil separator (must have been replaced before I got the car in 2003). I had a squealing noise that I could not located and which eventually went away (could this have a been associated with a vacuum leak from a failing separator?). Now I am having excessive smoke at startup. I removed the hose from the separator to the intake and there is some oil in it, could not tell if it was more than should be expected. With all hoses connected to separator and with car running I removed the oil fill cap. Cap was under vacuum and idle becomes rough immediately after removing cap (running lean from vacuum leak). Should the oil fill cap be under vacuum or is this a sign of a bad oil separator? Lastly I removed the hose from the intake hose from the separator and plugged it. Car does not smoke at startup, seems to idle better, and oil fill cap not under vacuum.

Any help is appreciated.

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my experience was a little oil film in the pipe between the separator and intake is ok, but enough oil to form drops is not.

I'm not sure how you tell whether the separator has internally failed or you have an air leak into the separator (from the bellows hose, the drain pipe seal, or the lower plastic tube connecting to the separator), but if I understood the operation of the separator correctly, then a checkvalve in the round part on top should prevent a lot of air flow through the unit. When a rubber diaphram tears, the checkvalve stops working and oil gets sucked into the intake. You'll find puddles in the intake plumbing forward of the throttle body.

If you are going to remove the oil fill pipe to make more room, use a heat gun/hair dryer at the joint to soften the plastic so you can separate the pieces. Try to prevent the hunk bolted to the engine from moving around a lot when you are tugging (and swearing) at the joint...it's pretty easy to snap the pipe where it makes the 90 degree bend down to the top of the block.

next up for my friends car is the water pump. It gave up at 51K miles.

I offered to buy the car off her for $13.50, but she's holding out for $22.75 :-)

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