MC engine - low oil pressure...Update 2

[ben swann]

Eliott,

AFAIK off hand, at least for the 4000's, the high pressure 1.8 bar
switch is in the top position.  That should be the same for all 5 cyl
motors, but I know it is for the 4kq, as I've encountered many lately.

I would not think the pump itself, but maybe the pressure relief valve
located in the housing, if I recall correctly.  Check to see if you
have one.  I had a pressure relief valve fail on a VW pump and lost oil
pressure entirely - the Castrol Syntec worked as advertised, an no
damage was done, fortunately.

I still maintain, the oil you are using is of to low a viscosity for
the type of "Non"-driving you are doing right now.  You should be using
crappy straight 30 weight for engine break in.  Good stuff won't let
your rings seat properly.

Ben
[Ok... I just did some more testing last night.

I conclude that:
-It's NOT the bearing clearances
-It's NOT the oil cooler circuit (length of lines, air, tempostat,
cooler obstructions)
-It's NOT the pickup tube sucking air or blocked

The only two things left for me to doubt are the oil squirters and the
oil pump itself.  I don't know what the problem could be with the
squirters unless they're stuck open and bleeding off a ton of
pressure.  The Bentley does say that the squirters regulate oil
pressure at idle and *should* only open above 35psi (might be wrong
about the exact figure).  Do these things go bad?

I'm leaning towards changing the oil pump based on the pressure when
cold.
Could it be that when the oil is thicker I see higher readings, but
when hot and the oil is thinner, the used pump might have a problem
trying to maintain adequate pressure?  I really didn't think the pumps
had any problems on these engines.

Speaking of oil, what is the ideal oil for these turbo motors? Others
have suggested that I'm using the wrong oil. I put in plane Jane 10W30
Castrol for the break-in period.

Next, I'm wondering about the setup of my oil pressure switches.  ET_KA
shows the two switches (the brown/black 0.3 bar unit and the white 1.8
bar unit) in varying positions.  It shows that on the 4kq the black 0.3
bar sender in top hole and that on the 5kt the white 1.8 bar sender is
in top hole.  Does the position of these senders matter at all?

The reason I ask is that I have my VDO gauge sender (two pin for gauge
and warning) in the top hole... Just wondering if the placement of
these things makes any difference.

Thanks again... Unless I have reason to think otherwise, I might be
changing oil pumps this weekend....

Elliott
86 4ktq
83 CGT
81 Coupe ITB
88 80 Fwd
Bunch of other VAG products]