Date:         Mon, 5 Feb 2007 23:32:28 -0500
Reply-To:     Benny boy <huotb@VIDEOTRON.CA>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Benny boy <huotb@VIDEOTRON.CA>
Subject:      Oil pressure explain!

Noob stuff for those who have no idea of what is "oil pressure" is (Bob,
Dennis and other, feel free to join me) Let's keep that simple!

Oil is a lubricant, your engine is metal on metal mooving part, not good, it
need oil to cool down /lubricate parts (the center of your engine is NOT
cooled by coolant!!! only the heads and pistons/sleeve section are(top end),
now, some part are dificult to reach (like rod bearing, cam, crankshaft,
rockers (in heads)). The crankshaft movement (remember those old
locomotives, when  we saw all the moving parts around the wheels, well, same
thing now but it's inside the engine) will splash oil on the cylinder
(bottom part) and the pistons lower oil ring will bring back that oil in the
center of the engine, so, cylinder are oil cooled and water cooled (water
jacket around those = this is why we called them wasser). Heads are water
cooled (because  it's where the hottest point of the engine is and they
don't really need oil, oil is NOT enough). Now, oil won't make it's way to
small, far or tight places (like in between bearing and cam, crank)
http://www.benplace.com/engine_view.htm

http://www.benplace.com/bjp/100_0084_78k.jpg

In that picture, you see the inside of an aircooled engine (same as a
wasser, yea!), you see where i put #1 #2 number, those are connecting rods,
yea, they are the link between the center part of your engine call the
crankshaft and the pistons. They are attach to those, but in between, they
have "bearing", those are there to absorb wear! but they need lubrification!
so in the engine you have a oil pump! that force/ push oil in those
locations trough a series of channels machined into the engine block, so, in
those line, before and after that pump (depend on which engine) VW put a
sender to tell you if the oil is passing ok. Ok, now why would a sender tell
you that the oil is not passing ok! well, the fist obvious one would be that
you don't have oil, but, the more precise one would tell you that those
famous bearing are worned out and oil is going through those one to easily
and not creating pressure. tight bearing will make a restriction and of
course create pressure. Leak could be from the rod bigger or smaller end
bearing, cam bearing or the crank bearing. So, if the oil is passing without
creating pressure, it mean that those bearing are to loose...

The conclusion: If you have a REAL low oil pressure problem... $$$ wil be
needed, but, you drive a VW, and VW have a lot of electrical problems. Also,
 those engine DON'T like thin oil, even new i'm sure, so thick oil help
create pressure. Why do they need thick oil is the question! Boxer Design
and gap/tolerance. I think that just by the way those channel are design,
including oil going to the hydro lifters that oil pressure is more dificult
to built up.

Understand one thing, those senders are switchs, that mean ON or OFF only,
and that, only at a certain pressure they will react, that mean sadly, too
low! Sender are directly hooked to that famous red light / buzzer in the dash.

The good things now, i hate VW, many already know that, but the center of
that engine was well built! so cheers to VW for that! i have seen core/small
block with over than 300k miles still going strong.

oil pressure sender are telling you 2 things (if working good), you have
enough oil, and you have enough pressure! now, what is enough!

Now, what we like to call the "idiot light problem" is only because the
engine is turning too low at idle and not making enough pressure, the sender
goes on and also the light, mostly on hot summer days when the oil get to thin.

I hope you have enjoy that basic explanation.
Ben