Thread: Experience of a catch can system...

I saw those vids a while back, yes. Interesting results I must say. Allow me to chip my 2 cents in having used the same provent for over 5 years now.

When I installed my completely rebuild engine 5+ years ago and went to the trouble of making it all bright and shiny new I really wanted to stop all that oil getting into the air intake, even though I have a V8 petrol and not a diesel so there really is no need for such a system. I know the provent is designed for diesel engines but I reckoned oil vapour is oil vapour, right?

The first time I checked the oil return line (I just had it hanging down to the ground with a ball valve) only a bit of brown moist came out. I guessed I was to impatient and gave it quite some more time/K's. After, say 10k I opened the balve valve back up and to my surprise mostly moisture was coming out with a brown tint, clearly oil or other particles. No obvious signs of thick oil that I was expecting anyway. Over the course of a couple of years I noticed the engine starting to leak, badly even, but not having experience with landrovers up until then and only knowing about all the jokes about leaking I thought; well, it's just my time for the oil leaks

In the interim I did begin to suspect that maybe my filter element was getting clogged up since they do have a limited lifespan. My filter might not look black but only brownish but hey, it's not a diesel. New elements are quite expensive but I bit the bullet and put a new one in. Perhaps it was wishful thinking but it seemed to work slightly better for a while however the oil leakage was back to normal in no time. Now that I have the engine out because of that crank end play issue mentioned elsewhere I have made quite a few observations:

• There is still oil in my air intake. Admittedly I did drive around for about 1 or 2K without it a couple of years ago between filter element changes becasue I wanted to see if the leaking would subside without the catch can but that either means that the can works REALLY well and the engine spits oil like crazy, or that the can simply does not filter it all... (my guess is the second)
• I suspect the provent causes over pressure in the engine causing oil to seep through, well, everywhere. My valley gasket was even bulging upwards slap bang up to the intake manifold. Now I know I don't have excessive blow-by since I checked for that so it can only be buildup due to insufficient release of pressure through the PCV which are "blocked" by the provent.
• There is water in all fuels but the water content in petrol seems to be higher. No I do not run fuel with bio ethanol in my car. The provent is always damp/moist on the inside and so are the vacuum lines. Only on very long runs at very high temps does all the moist dissipate. My guess is that the emulsion of water/oil is the culprit of clogging up the element quite fast, not one of the individual components.

All in all, it was a nice (and somewhat expensive) experiment but I can not recommend a provent on a petrol engine and with the results from this and others it is interesting to see what the real gain is on diesel engines.

Cheers,
-P

The biggest problem with catch cans,apart from having clowns fits them incorrectly,or kink the hoses,is lack of maintenance.

Not only do they need to be drained regularly,that is between services,but the filter also needs regular replacement,or it will over pressurise the crankcase.

Like any oil separator,they will only stop around 75 to 85% of the oil vapour at the most.