snip
This is false. When the PCValve ceases to flow air, then ALL crankcase pressure now vents out the 'breather hose' which you earlier described as the crankcase air inlet inside the air filter housing.
-Philip
"Old engines" would be prior to 1960.
An irony of 'green' legislation is that it left diesels free to continue "dumping overboard" (road draft tube) all crankcase blow-by until the mid
1980's for passenger car and small trucks, with commercial diesels until nearly 1990.-Philip
A clogged PCValve will not cause an engine to start using oil because ... the "breather hose" will now be the exclusive vent path for blow-by pressure in the crankcase.
-Philip
It you think BOTH Philip and Ed gave good explanations then you STILL don't understand this simple system.
-Philip
Yes...I believe that the oil control rings merely scrape oil from the cyl walls as the piston moves down to help keep it from getting past the compression rings...
Probably had to do with the number of the polluters?...I suppose there'd be many more car gas engines running so they got them first, then the next numerous etc? (just a wag though)
"J Strickland" wrote: snip
But Jeff, if your first cars didn't have a PCV then it had an overboard dump, what did Phillip call it? A road draft tube (or some such). They were usually near the rear of the engine,
Sure...by pressurizing the CC and forcing oil out of the bearings etc...
One more time ... just for GORD. A clogged PCValve does not cause the crankcase to pressurize. WHY? Because the 'breather hose' (aka, crankcase air *inlet*) now becomes the crankcase vent to atmosphere (not manifold vacuum). Having said this, IF the 'breather hose' is also restricted then ... the crankcase will pressurize.
Pressurizing the crankcase does NOT "force oil out the bearings." Good Grief, Gord! Are you eating those pot enriched brownies again?
-Philip
Lets take this a bit at a time here Phillip...if the CC pressurizes then what happens?...(according to phillip that is).
Valvoline 10W40, every 3000 miles
Aren't Ed and Philip saying the same thing, albeit a little differently?
I didn't save the post, but I thought that you both said the same thing a little differently.
Did I use too many words with more than two or syllables? Sit this one out, Gord.
Guess I should have said 'out the front and rear main seals'...so sorry great one...
You may address me as Your Maleficence.
Whatever turns yer crank Frank...
And, I thought I said essentially the same thing in my very first post, but admitted that it was a theory that I had, not an actual fact of operation. It turns out my theory was pretty close.
But, to consume a quart of oil in 1000 miles, doesn't there need to be significant blow by, and if there is significant blow by, doesn't this suggest problems with the rings, the oil ring at least, and probably the compression rings as well?
Sure, but I don't recall the motor sucking up oil by the quart every 1000 miles.
Bingo. But this causes oil on the outside of the motor, and probably on the ground under the motor. The OP claims to not have either, therefore his oil has to be going out the tail pipe, and this would mean valve seals and/or rings.
Sorry, that theory was not close.
You said: "My thoughts are that if the PCV is plugged, then under high vacuum, decelleration, oil can be forcibly sucked past the otherwise rasonably working rings. That is, even where the rings are working, but worn, the oil can be pulled past them if the PCV is clogged. I assume that if the rings are working at 100%, then the PCV wouldn't be all that improtant here, and plays a more signfiicant role on an older engine."
Oil does not get sucked past either good or bad oil control rings. For suction to take place, there has to be a vacuum, and there is no vacuum in the combustion chamber or in the crankcase.
No. I'm not sure what you mean by "significant," but some blowby will normally end up in the crankcase, which is the reason why it is ventilated.
and if there is significant blow by, doesn't this
Yes.
the oil ring at least,
No. Oil rings control oil.
and probably the
Yes. compression rings control blowby.
If the crankcase is vented to the atmosphere, then it is not connected to the intake manifold and so there is not connection betweent he cc and intake manifold.
Why do you keep going back to valve seals and rings?
The OP does not have smoke at startup. That pretty much rules out valve guide seals. If the valve guide seals are leaking, oil seeps and pools on the valve face while it is parked, and when the engine is started, the oil gets dumped into the combustion chamber and it smokes at startup until that oil is burned off.
The OP's wet and dry compression was OK, That pretty much rules out oil control and compression rings.
A properly working PCV valve opens when there is low manifold vacuum (off idle) and closes during high vacuum (at idle). If it stays open at idle, then the high vacuum can suck out some oil vapor and pass it through the intake manifold, where it gets burned..
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