UK-POLOS.NET - THE VW Polo Forum

Good morning all you petrol heads hahaha I have a headscratcher. The backstory!. Had this 2002 polo 1.4 bby for a few problem free years.recently it ate a timing belt and require the usual head job. Valves, seals, belts, tenioner, bolts, gaskets etc. Had the head at engineering shop for skim, Test, Valves cut etc.
Fitted the head with workshop manual in hand.
Then when I was driving my 140km daily commute after 2 days oil light come on. I found oil was very low and topped off. Also plugs and pistons oily. While stripping I found oil separator/pcv blocked solid at oil return port(lower d-shaped port) mind you I always serviced on time with syth 5w40 oil so this must have be pre-existing. Anyway I cleared the ports which had substantial blockages engine side as well and replaced seals. After another 2 days commute only about 5mm oil on dipstick. Parked the car and 2 days later the oil has magically reappeared. So I know that oil is not returning to the sump fast enough but my problem is where can around 2.5 liters of oil hide away undetected in a little 1.4L. My next step is drive the car and immediately remove oil separator. Im checking for a possible further blockage there. Your thoughts greatly appreciated. Feel free to ask any addition info because this post is quite long already.

I had a BBY many years ago, after roughly 90,000miles it started pinking or pre-igniting under load at low engine revs, I stopped that by only using 97/98/99 Octane fuel while trying to find out what the root cause was, it was "using" too much oil but nothing like your car is.

I eventually replaced the oil separator and that slowed down the oil usage and the pinking, but due to the much improved drivability at low revs that the higher octane fuel provided, my wife did not let me revert to using 94 Octane fuel.

I think that these cyclonic oil separators do clog up or reduce to be effective with age and should be viewed as being a "service" item.

Also try to locate the crankcase emissions valve as that should be limiting the volume of air being drawn through the oil separator - as well as any other induction air leaks, I think that the crankcase emissions valve should almost shut off the purging air during low engine revs at which time the engine is working very well as a vacuum pump so will gulp in air from where ever it can, and if the purging air is not being limited, it will draw a lot of oil through into the inlet manifold.