tzrider Posted April 9, 2007 Share Posted April 9, 2007 My daily commute mainly consists of a 10 mile, 3500' elevation gain stretch. On the return trip I coast in 3rd gear (97 OBW, automatic, 208k mi). When the grade levels out for the last 2 miles, I put the tranny in D and hit the gas. The car burns oil for the entire 2 miles (I can see this in the rearview). This is the only time the car burns oil like that; otherwise, it burns very little. Any insight as to why this is happening? Thanks for the help... Quote Link to comment Share on other sites More sharing options...
OB99W Posted April 9, 2007 Share Posted April 9, 2007 Descending a hill is a condition when the throttle is closed, intake vacuum is high, and combustion chambers cool down. Oil gets past rings, and especially past worn valve stem seals, and doesn't get much of a chance to burn off. When you level off and open the throttle, you're moving a lot more through the engine and the combustion temps go up, burning off the accumulation. Bingo, instant smokescreen. Quote Link to comment Share on other sites More sharing options...
nipper Posted April 9, 2007 Share Posted April 9, 2007 Just for the heck of it, when was the last time the PCV valve was replaced? nipper Quote Link to comment Share on other sites More sharing options...
OB99W Posted April 9, 2007 Share Posted April 9, 2007 Just for the heck of it, when was the last time the PCV valve was replaced? Good point, Nipper -- a clogged PCV (valve and/or hoses) can allow the crankcase to pressurize and increase the likelihood of the problem. Quote Link to comment Share on other sites More sharing options...
mtsmiths Posted April 9, 2007 Share Posted April 9, 2007 Good point, Nipper -- a clogged PCV (valve and/or hoses) can allow the crankcase to pressurize and increase the likelihood of the problem. Agreed, back in the old pepper tree mechanic days ... before any pollutiion devvices had been invented (even the PCV valve), I was always taught blue smoke on acceleration = rings, blue smoke on deceleration = valve guides. In this case, I too voe for a clogged PCV valve. Quote Link to comment Share on other sites More sharing options...
Snowman Posted April 9, 2007 Share Posted April 9, 2007 Just for the heck of it, when was the last time the PCV valve was replaced? nipper Bingo. I would bet ten bucks it's the PCV valve. Get a genuine SOA one as the aftermarket ones are crap. This is a very common problem in Subarus of pretty much every generation. Quote Link to comment Share on other sites More sharing options...
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