Well, my 99 OB Wagon has had an oil leak for a while and last month I did a tune-up (changed plugs, wires and the PCV) The PCV came out looking quite bad (I'm sure it was plugged).
Well after the installation of new PCV I've had no smell of oil and the front leaking seems to be gone.
This all makes sense because the crankcase pressure (which should not be a pressure at all) was probably forcing the oil past the seals. With the new PCV this pressure is not a pressure at all - it is a vacuum.
Manifold vacuum is fine. Are you suggesting that there is another problem I've not addressed?
I believe it's normal maintenance to have to clean or replace a PCV so that it does not fail clogged? (I just overlooked it) All engines have blow-by. I believe stopping blow-by from purging into the air is what the PCV system is suppose to do. And given that blow-by is a product of hot exhaust gas I think even the newest of engines will create blow-by with carbon which will eventually plug a PCV valve. I don't think there is anything else wrong at this point, but if you do, please suggest what I should be looking for.
Hmmm, In many years driving I really never saw a clogged up PCV. I used to clean it a few times. When engine is idle manifold vacuum is highest keeping it close. As engine revs up vacuum level drops and it starts to open. Older engines need higher flow PCV. Some times crankcase pan has sludge build up clogging things up. How often you do oil/filter change? How often you go out onto freeway and do WOT crusing to keep engine clean burning off build up?
I have read of people claiming Sube PCV systems can clog/fail in such a way that it causes excess leakge/usage of oil. Dunno how common it is. I have also read folks claiming engine braking will exacerbate the problem.
At 55kmiles the PCV on my H6 was well and truly plugged.
There is a vent from the crankcase into the air intake system, (there is on everything else, assume subes are the same?) so a bad PCV won't really cause a pressure buildup.
Dunno about other models, but w/ some earlier engines this venting system was sometimes inadequate, even w/ a good PCV valve. My '90 EA-82 engine had a weird problem: fast sweeping right hand turns (like many freeway onramps) would result in the engine trying to stall w/ huge clouds of white smoke out the exhaust.
Turns out the hoses on the left side of the engine (looking forward from driver's seat, US model) were smaller diameter than the right side. A little research revealed a TSB w/ new part numbers. The replacement hoses were same diameter on both sides w/ a slightly different flow pattern thru the connector. Problem solved.
Another area to pay attention to is in the valve cover: there can be a build up of crud in the junction where the hoses are connected (both sides) so cleaning's required periodically depending a lot on driving style. My limited experience w/ crankcase ventilation systems indicates Subies might not be at the top of the heap for great design, so a little extra attention's probably not wasted effort.
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