No Oil Filter???

On Wed, 10 Nov 2004 23:39:39 GMT, "Raymond Lowe" >
wrote:

>Shaggie wrote:
>> On Wed, 10 Nov 2004 21:59:07 +0200, Jan Andersson
>> > wrote:
>>
>>> John Connolly wrote:
>>>>
>>>> it flows both ways in that tube Jan. It flows from crankcase to air
>>>> filter
>>>> when the crankcase is pressurized (when the engine is making
>>>> power), but it flows the OTHER WAY during high vacuum decelleration
>>>> (downshifting).
>>>
>>>
>>> Sounds like your rings are shot John Either that or you
>>> converted to 2-stroke
>>>
>>> Please explain to me where the vacuum inside the engine case comes
>>> from?
>>
>> I've been wondering where the vacuum during deceleration in the
>> crankcase comes from. I didn't know that happened. I can understand
>> the vacuum in the intake manifold during deceleration, but not in the
>> crankcase. I mean the throttle closes so air/fuel isn't dumping into
>> the intake, but the pistons are still going and sucking in what they
>> can through the intake valve on the intake stroke so that would cause
>> vacuum in the intake area. I don't get it for the case, though.
>
>On the power stroke, the hot gasses are forced behind the rings and the
>pressure expands them outward to the cylinder surface. This is how the
>rings seal. On the intake stroke, the rings have only internal tension
>holding them outward which means they seal far less.
>
>When the vacuum spikes on deceleration, this is felt in the combustion
>chamber during the intake stroke. Especially since you no longer have
>the charge velocity to compensate.

I understand that much 100%...

> And, with very little happening on
>the power stroke to offset this,

"this" = what? I think you mean "this" = "vacuum on intake/combustion
side."

> the net result is vacuum (or suction)

Suction on intake/combustion side of things on the power stroke,
right?

>drawing crankcase air around the rings and through the ring gaps.
>The resulting vacuum in the case draws air in from your vent.

So you're saying all of the vacuum in the crankcase is a result of
vacuum in the intake/combustion and is from gases escaping past the
piston rings? Like osmosis or something, right? Stuff moving through
a semi-permeable membrane (around the rings) from an area of higher
concentration to an area of lesser concentration or something to move
towards forming a happy balance in pressure? If that's the case I'd
hope that at least the vacuum in the crankcaseseen on deceleration is
several orders of magnitude less than what is seen on the
intake/combustion side of the piston or I'd think you've got some
serious ring wear. Unless I didn't understand your explanation.
Thanks for at least trying to explain it to me. I'd love to know if I
followed your explanation ok or if I missed something.

--

Always carry a flagon of whiskey in case of snakebite,
and furthermore always carry a small snake.
- W.C. Fields

Shaggie wrote:
> On Wed, 10 Nov 2004 15:30:16 -0800, "Mike Rocket J. Squirrel Elliott"
> et> wrote:
>
>
>>Shaggie wrote:
>>
>>>On Wed, 10 Nov 2004 15:16:22 -0800, "Mike Rocket J. Squirrel Elliott"
>>><j.michael.elliottAT@REMOVETHEOBVIOUSadelphiaDO T.net> wrote:
>>>
>>>
>>>
>>>>ilambert wrote:
>>>>
>>>>
>>>>>Wrong guess.The bus is a '71,the engine is mexi.I would guess it uses the
>>>>>later style cam,hence the later style pump.
>>>>
>>>>Give the man a cigar -- CB Performance finally got back to me and
>>>>confirmed what you, and others, have said: use the later style. Thanks
>>>>for the help!
>>>>
>>>>
>>>>
>>>>>By the way.what is the advantage
>>>>>why did VW change the design?Curious.
>>>>
>>>>This, I reckon, is a Bob Hoover or Jan kinda question.
>>>
>>>
>>>OK, then I won't answer it... :-)
>>>
>>
>>Okay then. Make that a Bob Hoover, Jan, or Shaggie kinda question.
>>
>>Your move.
>>
>>--
>
>
> *knocks chess pieces all over the board with frustrated look*
> OK, where's Bob or Jan when you need them!?!? ;-)
> I dunno, dude. I was just feeling left out and trying to be a part of
> things. *sniffle* Wow, Dan Rather almost cried during the closing of
> the news just now. I'm kinda shook-up over that. :-/
>

Jeez, Shaggie -- I'm sorry! Didn't mean to overlook you! But now that
you've made a scene about it and everyone in class is looking at you,
come up to the front of the classroom and tell everyone what you know
about dished cams.

--
Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westphalia: "Mellow Yellow (The Electrical Banana)"
KG6RCR

On Wed, 10 Nov 2004 16:18:41 -0800, "Mike Rocket J. Squirrel Elliott"
et> wrote:

>Shaggie wrote:
>> On Wed, 10 Nov 2004 15:30:16 -0800, "Mike Rocket J. Squirrel Elliott"
>> et> wrote:
>>
>>
>>>Shaggie wrote:
>>>
>>>>On Wed, 10 Nov 2004 15:16:22 -0800, "Mike Rocket J. Squirrel Elliott"
>>>><j.michael.elliottAT@REMOVETHEOBVIOUSadelphiaD OT.net> wrote:
>>>>
>>>>
>>>>
>>>>>ilambert wrote:
>>>>>
>>>>>
>>>>>>Wrong guess.The bus is a '71,the engine is mexi.I would guess it uses the
>>>>>>later style cam,hence the later style pump.
>>>>>
>>>>>Give the man a cigar -- CB Performance finally got back to me and
>>>>>confirmed what you, and others, have said: use the later style. Thanks
>>>>>for the help!
>>>>>
>>>>>
>>>>>
>>>>>>By the way.what is the advantage
>>>>>>why did VW change the design?Curious.
>>>>>
>>>>>This, I reckon, is a Bob Hoover or Jan kinda question.
>>>>
>>>>
>>>>OK, then I won't answer it... :-)
>>>>
>>>
>>>Okay then. Make that a Bob Hoover, Jan, or Shaggie kinda question.
>>>
>>>Your move.
>>>
>>>--
>>
>>
>> *knocks chess pieces all over the board with frustrated look*
>> OK, where's Bob or Jan when you need them!?!? ;-)
>> I dunno, dude. I was just feeling left out and trying to be a part of
>> things. *sniffle* Wow, Dan Rather almost cried during the closing of
>> the news just now. I'm kinda shook-up over that. :-/
>>
>
>Jeez, Shaggie -- I'm sorry! Didn't mean to overlook you! But now that
>you've made a scene about it and everyone in class is looking at you,
>come up to the front of the classroom and tell everyone what you know
>about dished cams.

They're dished.
*shuffles feet, tries to hide boner that popped up at the worst time
like they always do*

--

Always carry a flagon of whiskey in case of snakebite,
and furthermore always carry a small snake.
- W.C. Fields

"Mike Rocket J. Squirrel Elliott"
et> wrote in message
...
>
> Jeez, Shaggie -- I'm sorry! Didn't mean to overlook you! But now that
> you've made a scene about it and everyone in class is looking at you,
> come up to the front of the classroom and tell everyone what you know
> about dished cams.
>
>


...............This is going to be good.

<getting my spitballs ready>

Shaggie wrote:
> On Wed, 10 Nov 2004 23:39:39 GMT, "Raymond Lowe" >
> wrote:
>

[BIG ol' discussion snipped]

> Thanks for at least trying to explain it to me. I'd love to know if I
> followed your explanation ok or if I missed something.
>

Keep askin' questions, Shaggie -- I'm totally drawing a blank on this
whole vacuum in case issue. Raymond: you took a good shot at explaining
it, and for someone sharper than me, a light bulb might have gone off,
indicating enlightenment. But as it stands, I am benighted in my
inability to understand how the case can have any vacuum at all. All I
picture is this big hot magnesium box with pistons going in and out,
those going out matching the swept volume of those going it, and bitty
bursts of hot gases leaking into the case on every power stroke. The
very concept of the case developing negative pressure w/r/t the outside
world boggles me.

--

Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westphalia: "Mellow Yellow (The Electrical Banana)"
KG6RCR
-=-=-
The fact that it works is immaterial.
-- L. Ogborn
------------------------------------

Umm.. because I'm a pain in the ass, and because I have nothing better to do, I
just thought I would point out that Jan said:

>The most important thing in my opinion will get
>adequately taken care of: pressure relief.

And:

>white creamy mayonnaise-like substance

in the same post. Just found that interesting.


Kidd


"We're friends. You smile, I smile. You hurt, I hurt. You cry, I cry. You jump
off a bridge.... I'm gonna miss your dumb ass."

How can it get pressurized Mike? Could it be that pressure in the combustion
chamber makes it's way past the rings and pressurizes the crankcase?

Under decelleration, you have an engine that's trying to turn fast, and a
closed throttle, resulting in a high vacuum. Now air in the crankcase is
sucked into the chamber (again, past the rings).

you can't assume the rings are 100% effective, then it makes some sense. The
entire reason you need a crankcase vent in the first place is because of
combustion gasses making their way past the rings. The same issue is present
under high vacuum.

John
Aircooled.Net Inc.

Kidd Andersson wrote:
> Umm.. because I'm a pain in the ass, and because I have nothing better to do, I
> just thought I would point out that Jan said:
>
>
>>The most important thing in my opinion will get
>>adequately taken care of: pressure relief.
>
> And:
>
>>white creamy mayonnaise-like substance
>
> in the same post. Just found that interesting.
>

Wow. And I thought that /I/ had a dirty little mind. But Kidd:
"Mayonnaise-like"? What's Jan been eating?

--
Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westphalia: "Mellow Yellow (The Electrical Banana)"
KG6RCR

John Connolly wrote:
> How can it get pressurized Mike? Could it be that pressure in the combustion
> chamber makes it's way past the rings and pressurizes the crankcase?
>
> Under decelleration, you have an engine that's trying to turn fast, and a
> closed throttle, resulting in a high vacuum. Now air in the crankcase is
> sucked into the chamber (again, past the rings).
>
> you can't assume the rings are 100% effective, then it makes some sense. The
> entire reason you need a crankcase vent in the first place is because of
> combustion gasses making their way past the rings. The same issue is present
> under high vacuum.

Hang on -- when a piston is pulling against a vacuum there certainly is
a pressure differential across it. And the most extreme case would be if
there was a total vacuum in the combustion chamber. The inside of the
case is pretty close to atmospheric pressure -- 16psi. So the maximum
pressure differential across the piston would be 16psi and not an ounce
more. That's several orders of magnitude less than the pressure on the
outside of the piston when the air/fuel mixture is burning during the
power stroke -- anyone got the figures for peak combustion chamber
pressure for these engines?

(Of course, if the rings leak a lot when there isn't much pressure
across the piston, and very little when the pressure is great, or if
they seal better in one direction than another, my whole argument
collapses like a bunch of broccoli.)

--
Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westphalia: "Mellow Yellow (The Electrical Banana)"
KG6RCR
-=-=-
Actual Test Answers Music Teachers Have Received, #27:
My favorite instrument is the bassoon. It is so hard to play
people seldom play it. That is why I like the bassoon best.
------------------------------------

Chris had already answered why they changed the design.Makes sense too.More
meat at the cam/pump interface.
"ilambert" > wrote in message
...
> Wrong guess.The bus is a '71,the engine is mexi.I would guess it uses the
> later style cam,hence the later style pump.By the way.what is the
> advantage why did VW change the design?Curious.
> "Chris Perdue" > wrote in message
> ...
>> >From: "Mike Rocket J. Squirrel
>>
>>>If I had to hazard a guess, I want the first type, the #1798 because
>>>their dating scheme is probably for bugs and the bus had the upright
>>>engine into 1971. Good guess?
>>>
>>
>> your late model replacement engine will contain the 71+ "dished"
>> cam....all
>> aftermarket performance cams are the "flat" (pre 71) cam...the dished cam
>> has
>> four rivets holding the cam gear on and is "dished" in the center...so
>> the pump
>> has a longer shaft(from the gear) to meet up with the slot in the cam,w
>> hich in
>> turn, um, turns the gear to pump the oil....the later ones can have the
>> gear
>> pressed further onto the shaft and the shaft ground down flush if for
>> some
>> reason you would have the early cam(VERY doubtful, as far as i know all
>> factory
>> cams(like in your factory longblock) had the dished cam from 71...i have
>> torn
>> down two in the past couple years that were replacement engines and they
>> were
>> dished....)
>> -------------------
>> Chris Perdue
>> "I'm ever so thankful for the Internet; it has allowed me to keep a
>> finger in
>> the pie and to make some small contribution to those younger who will
>> carry the
>> air-cooled legend forward"
>> Jim Mais
>> Feb. 2004
>
>