Date:         Fri, 26 Apr 1996 06:16:27 -0400
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         "Kirk D. Hilliard" <kdh5j@emmy.math.virginia.edu>
Subject:      Re: Oil Press. Sender location(T4)

[ Concerning tight fit for oil pressure gauge sender on type IV engine ]
Aaron Wood <afn32620@freenet.ufl.edu> said:

> the threads on the sender are 1/8 in tapered National Pipe Threads(NPT).

Really?  Not some bizarre metric size?  Well, that should help.

> I went to the hardware store and bought a two inch piece of brass
> pipe and a brass "T", all having 1/8 in NPT.  I screwed the pipe
> into the existing hole, screwed the "T" onto the pipe(so that there
> was on horizontal and one vertical hole), screwed the original idiot
> switch into the top hole and the new sender in the horizontal hole.
> Everything fit just great.

Sounds good.

> As I looked at the setup my brain began to think on its own, 
> hmm, the pipe makes the two senders the highest point on the engine.  
> Air flows to the highest point.  Damn, air will get into the pipe and 
> screw up all the readings.
[ elaborate scheme to bleed air out of the extension deleted ]

As a fluid, shouldn't air be a fine medium to transmit the pressure?
In fact, due to its lower density resulting in lower head losses,
shouldn't the sender be getting a more accurate reading if there is
air in the extension.  (This is of no practical benefit since a few
inches of oil translates into only a fraction of a psi.)  Did you fire
the engine up with your first configuration?

I will speak to technical assistance at RMMW (from whom I bought my
VDO sender and gauge) and see what they have to say about the
situation.  I called my salesman yesterday (after the technical
representative had gone home) and he said that he sells the senders
all the time and has never heard of this problem.


David Schwarze <ddes@zeus.anet-dfw.com> wrote:

> VDO has an extension hose for this purpose.  I have used it for
> about 4 years with no problems.  Good VW parts places should stock
> it, or at least be able to order it.  If you get desperate, call Vee
> Parts in San Diego at 619-477-4787 and ask them if they will mail it
> to you.  I think it runs around $15-20.

Yesterday I spoke with a salesman at Vee Parts.  After I finally
convinced him that I was looking for an extension, not a new piece of
tin with a larger hole (him: "Oh, you want an extension!"  me, out
loud: "Yes!"  me, to my self: "Thats what I've been saying that I
wanted for the last half hour.") he said to call back after fifteen so
he could have a chance to ask around about it.  When I called back he
said that no one there had ever heard of such an animal.  "People buy
these senders all the time and nobody has ever called about this
problem before.  They must just use tin snips."


In a related note, my owner's manual says that the brake warning light
is supposed to come one whenever the oil warning light is on (only the
brake warning light will come on if the oil pressure is up and the
emergency brake is engaged or there is a brake circuit failure).  The
rationale is that the brake warning light will help attract the
attention of the driver in case of low oil pressure.  I don't know if
it is supposed to be done via a diode or a relay, but it doesn't work
with my 1977 camper.  Does this work for anyone else?

Kirk Hilliard
kdh5j@virginia.edu