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6 replies to this topic

#1 wintersubaru

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Posted 13 April 2005 - 07:57 PM

I have noticed that when i take the breather tube off the right valve cover that a lot off blow by was coming from it when i pulled it to pour some sea foam down it with it running. So my question is what is the cause of this? the left side is fine. The T.O.D. is louder on the right side. thanks for the feed back

#2 subyrally

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Posted 13 April 2005 - 08:01 PM

when my rx was having blowby issues, it turned out to be a blown piston ring.

#3 All_talk

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Posted 13 April 2005 - 09:04 PM

Yep, blow-by is due to poorly sealing pistion rings (worn, broken or stuck), and/or baddly worn ring lands. The way the stock PCV system designed, fresh air is draw in at the passenger side valvecover and case vapors are drawn out on the drivers side, but if the PCV valve is stuck or the blow-by is bad enough it will push vapors and oil out both (and a whole lot of other places).

Gary

#4 wintersubaru

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Posted 14 April 2005 - 06:44 PM

Yep, blow-by is due to poorly sealing pistion rings (worn, broken or stuck), and/or baddly worn ring lands. The way the stock PCV system designed, fresh air is draw in at the passenger side valvecover and case vapors are drawn out on the drivers side, but if the PCV valve is stuck or the blow-by is bad enough it will push vapors and oil out both (and a whole lot of other places).

Gary

no oil comming yet so maybe pcv valve i hope.

#5 markman34

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Posted 22 June 2005 - 04:24 PM

interesting that there is a flow from one side to the other with the pcv system.

I have hooked up a catch can that accepts both pcv nipples off of the valve covers. Is this bad?
Do I need to have the one side connected to the air cleaner boot? Does this side (passenger side) provide fresh air to the pcv system?
very interesting........
Is there a hazzard to not having the air supply to the pcv system?
When does the pcv valve open? Does it fail open? Does it operate on vacume or fluid level?
And...... what is a normal amount of pcv gas coming out of the engine. My oil filler cap huffs pretty hard when I take the cap off.

So many questions

#6 NorthWet

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Posted 22 June 2005 - 04:57 PM

Ok, PCV 101:

A standard PCV system is designed so that it ventilates the crankcase under both low-load, high-vacuum and high-load, low-vacuum conditions. To handle the low-load, high-vacuum, a hose is connected from the crankcase to the intake manifold "below" the throttleplate using a PCV valve, which is pretty much just a spring-loaded check valve that prevents backfires from igniting your crankcase. For high-load, low-vacuum, the system has a line that runs to the intake system "above" the throttle plate (usually air cleaner housing). Additionally, there is usually a vent line that takes filtered air from inside the air cleaner housing.

The PCV valve usually fails due to getting gummed with gunk, so it can fail closed, open, or part way between.

The oil filler "huffing" is probably little more than the crankcase "pumping" air as the pistons move.

If one valvecover vent is moving air and the other is not, I might check the one that is not and make sure it is not obstructed. They are both connected to the same pressure source (the crankcase).

#7 1984subaru

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Posted 24 June 2005 - 12:32 AM

I have noticed that when i take the breather tube off the right valve cover that a lot off blow by was coming from it when i pulled it to pour some sea foam down it with it running. So my question is what is the cause of this? the left side is fine. The T.O.D. is louder on the right side. thanks for the feed back



BLOW BY ON SUBARU STANDARD




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