i have VDO oil temperature and oil pressure sending units from an older audi.
Where do i install them? as far as i know the low oil pressure switch is on the driver side of the head and the high pressure switch is on the filter flange.
My pressure sender is a 2 pole type, 1 for the oil pressure gauge and the other for the switch i believe.
thanks, Sabi

>>the oil temp i m not sure, but you would put the pressure sending unit up on the head where the switch is now

That's correct.  My sending unit  came from a gas cabriolet that had the unit installed in the same location.

FWIW, the oil temp sending unit on the gas cars is on the oil filter flange.  I don't think there's a spot for it on the diesels.  I wonder if the gas engine flange would swap in directly.  Anyone have any info? Maybe there's a simpler solution...

 I'm going to use a GTI console / gauges in the caddy, so I'm interested in having a functional temp gauge as well.

There should be two "switches" on the engine... a low pressure switch for idle up to 2000 rpm or so and a high pressure switch for everything above that.

The low pressure switch has a limit of around 5-7psi (I believe), so if you go below that at idle, it'll blink or stay on.  If your light/buzzer goes on when your rev the engine (above 2k) normally, that's a wiring / sender problem with the high pressure switch.

The sender that we'll be using in the side of the head should have two poles as you said... one for the gauge output and one for the "idiot light".

Is it possible that your wiring got switched or there's a problem with the sender?

Hmmm...  Just found this on the net while searching...

"According the the Bentley manual there are 2 oil pressure switches. A
0.3 bar pressure switch which provides warning when the oil pressure
falls to near zero at any time, including at idle.  A 1.8 bar pressure
switch (1.4 bar on diesels) provides earlier warning, at elevated
rpm, whenever oil pressure falls below a minimum save level.  This is
for all Golf/Jetta 1985 - 1992. "

Do you only have one oil pressure sender or two?  My 1.5 only has one in the side of the head (I believe). You should be able to find the "specs" of your stock senders by looking at the wrench flats on the base of the sender.  It might be a bit dirty there, but clean it up and you'll see the pressures engraved there.

The dual sender that I have says 0 / 5 bar and 1.8 +/- 0.2 bar.  That would mean that you need to put the gauge sender in place of the stock high pressure sensor you took out that's closest to 1.8 bar.  

Incidentally, I found out the logic behind the markings on the two poles on the gauge sender.  One pin is marked 'G' (for "Geber", german for sender) and the other is marked 'WK'  for ""Warnkontakt", (German for "warning contact").    

If you do indeed have two senders, you could do a quick check by  temporarily connecting the wires the other way.  You could use some jumpers and see if the behavior changes.  

In other words,  leave the gauge sender installed as is for the moment and then connect the b/wh to the filter flange sender and the yellow one to the second pole on the gauge sender (marked "WK").

Let me know... I'm interested in this as well.

What about a "tee" for splitting out the location for use with both senders?  I know we both have the two pole senders, but this way you could retain your factory rated high pressure switch...

Here's one company that has something like that...(no affiliation)

http://www.42draftdesigns.com/product/42004.htm

http://194.242.159.246/brickyard/info/dop.htm

I have a T3 (Vanagon) with a 1.9 M-TDi
The VDO sender I have is fitted to the oil filter head.
The buzzer of doom works as it should.