blow-by. how much is to much.

Heads, valves, pistons, rods, crankshaft, etc...

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Piperpilot26
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Posts: 6
Joined: Tue Dec 16, 2008 1:24 am
Location: Wallingford ct

blow-by. how much is to much.

Post by Piperpilot26 »

hello,

I just wanted to start off my saying that subaru's are by far the greatest and most reliable cars ever invented. :D Anyways, let me give you guys a little info on the car before I ask my question. I have a 93 subaru legacy wagon with 208,663 miles. I purchased the car in 2005 with 128,016 miles. within the 3 1/2 years I've been driving the car, I have changed the oil every 2,500-2,900 miles using mobile non synthetic. I haven't done any major services to the engine yet, I just change air/fuel filters and spark plugs. throughout the eighty thousand miles I've put on the car, its maintained the same fuel economy(24-30mpg) and consumed very little oil(I never had to add oil between oil changes). within the past year I've switched to synthetic with no problems. anyways, just recently took my oil cap off while the engine was running just to check for blow-by and I noticed that there was a pretty fair amount of air puffing out(puff puff puff) like that. no gasses or smoke, just air. Is this normal? or is it a sign of worn or broken compression rings?

P.S. I also dont beat on the car, I let it run every morning until I see the temp needle start to move(usually 2 minutes) and I rarely let the engine see over 3,000 rpm. I cruise at the same rpms (highway/ 5th gear at 2,500 and backroads/4th gear 2,200 rpm

thanks and any advise will be greatly appreciated.
ericem
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Joined: Mon Oct 16, 2006 9:44 pm
Location: Toronto,ON Canada

Post by ericem »

My car does the same. Have not checked it after I replaced all my PCV tubes and all.
1993 Subaru Legacy L AWD Wagon R.I.P
1994 Subaru Legacy SS R.I.P :(
2004 Nissan Titan LE 4X4
2007 Subaru Legacy GT :)
Piperpilot26
In Neutral
Posts: 6
Joined: Tue Dec 16, 2008 1:24 am
Location: Wallingford ct

Post by Piperpilot26 »

cool, yeah I just replaced the pcv valve, its a little better, but its still there..
jefferson
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Location: Parkville, Mo.

Post by jefferson »

I would say you don't have a problem. What you are feeling is the air being pumped out by the pistons moving down to bdc. You just gave it an easier way to get out when you removed the cap.

Jeff
91 Black SS 5spd. Edm lights, wrx gauges in dash, 45 degree airbox, cryoed drilled and slotted brakes. Invidia divorced downpipe with custom stainless exhaust. To be installed, aluminum a-arms, manual belts, awic.
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