[Vwdiesel] Oil Pressure Warning System on '84 Rabbit

[Terry Briggs]

The oil pressure on my '86 na is between 40 psi and 90 psi all the 
time. over 100 psi when it's really cold on start up. Never seen it 
below 40 psi even at idle. just running down the road at 70 mph and I 
have around 75 psi.
On Sep 1, 2006, at 9:24 AM, Bryan K Walton wrote:

> I'm trying to understand the oil pressure warning system on my '84
> (non-turbo) Rabbit.  According to Mr. Bentley, here is what I THINK
> I understand:
>
> There are two switches on my rabbit.  First, there is a normally
> closed oil pressure switch on the cylinder head that opens between 2.1
> and 6.4 psi.  Second, there is a normally open switch on the oil
> filter bracket that closes between 23-29psi.
>
> The first switch (on the cylinder head) causes the idiot light to
> light up for a few seconds after the car starts up, then the light
> should go out.  Then, if the car is above 2000rpms (and if I understand
> this correctly), and the pressure drops below 29 psi, the switch on the
> oil filter causes the idiot light to light up AND a buzzer to go off.
>
> Is this a correct summary of how this works?
>
> What I'm SURE I don't understand is the following:
>
> 1. If the first switch only operates between 2.1 and 6.4psi, and the
> second one only operates between 23-29psi, what happens if the
> engine is over 2000rpms BUT the pressure is somewhere between 6.4 and
> 23psi?
>
> 2. Bentley seems to say that there is a oil pressure bypass valve that
> sends oil back to the crankcase IF the pressure gets over 22psi.  That
> would seem to tell me that the pressure should NEVER be more than
> 22psi.  But Bentley also says that the minimally acceptable oil
> pressure at 2000rpms is 29psi.  So, what am I misunderstanding here?
>
> 3. Final question, if the ideal oil pressure at 2000 rpms is 29psi,
> can I extrapolate that ideal pressure at the following rpms is:
> 1000 rpms:	15psi
> 3000 rpms:	44psi
> 4000 rpms:	59psi
> etc...
>
> Can somebody please shine some light on my mental shortcomings here?
> Thanks!
> Bryan Walton
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Third Wheel engineering
Custom Design and Fabrication
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