Aux oil gauges fault.

[Nuvo]

Both my oil temp and pressure gauges display full scale deflection when the car is started up.
Oil pressure read ~1 bar with the ignition switch in the first position, temp is fsd.

Anyone seen this fault condition before?

Is it possible to identify the G and the WK terminals on the pressure sender/switch by which one has the protective rubber boot? I know they are stamped on the body but I can't read them. I would expect the signal wire (G) to be the protected terminal but I'd like that confirmed if possible.
The colouring of the wires doesn't correspond to the wiring diagram I'm using.

Any tips on freeing of the spade connector from the terminal I have tried soaking it with penetrating fluid and gently prising it with a flat blade screwdriver but it refuses to yield.

[newsh]

It might be one of those weird spade terminals with a catch, look for a small spring or lever at the wire end of the spade.

[Nuvo]

Thanks, that could be a possibility. I'll be sure to take a closer look.

[newsh]

Here's a couple of examples of the type, they can feel like they're loose but just not come off.

[UrS4boy]

Oil Pressure Sender, Switches, Wiring and Check Valves

When the oil pressure sender has wiring issues, the resulting gauge reading goes full on (5 Bar +) and stays there.

Oil Pressure Sender, Switches, Wiring and Check Valves:

http://forums.quattroworld.com/s4s6/msgs/96161.phtml

[andy10v]

Broken wire/disconnected pegs the gauge, I was surprised as I would have thought no signal no reading.

Check its connected, then check continuity or swap sender?

[Mikes2]

WK is the terminal for the pressure gauge

Interesting that the oil temp is off the scale also. There is only one wire for this and when you earth the wire you would expect to see full scale. Looking like a shorted wire somewhere

[K Simmonds]

I had very similar problem when I put my S2 back on the road a couple of years ago, the oil temp gauge read off the scale as soon the engine started and the oil pressure gauge had a mind of it's own occasionally reading off the scale or nothing at all.

I traced it to corroded connections in the plug behind the gauges themselves that connects the gauge loom to the main loom, I cleaned the male one's with a tiny file as well as tightening the female side's with a fine pick and they've been fine since.

Maybe worth a look at the condition of the pins in said connector, .

[UrS4boy]

WK is the terminal for the pressure gauge

Not according to the diagram I posted.

[Nuvo]

Thanks for the replies everyone.

Okay, Time to update my findings from this morning.

The single wire that runs to oil temp sender mounted in the oil pump was short circuit to ground via the block.
The insulation had evidently dried out and split from its exposure to heat cycling over the years. I repaired the insulation and the temp gauge now works as it should.

The wiring to the sender checked out fine, the pressure sender has a high resistance of >1KΩ between the G terminal and ground when measured cold.
Therefore the sender needs replacing.

@Newsh, I managed to free off the stubborn spade terminal with a series of what I will call "micro wiggles" after gently cleaning the verdigris with a small brass wire brush.

Did I read a post on here that VDO senders are NLA from Audi and the ones supplied from VDO have a tapered thread which doesn't fit?

So what are my options here aside from finding a good used one, can I possibly get one new from the Porsche parts bin, 944 or similar vintage maybe?

How about the idea recutting the threads of a VDO supplied sender to fit the block? Has anyone done this before with success?

Thanks chaps.

[UrS4boy]

Did I read a post on here that VDO senders are NLA from Audi and the ones supplied from VDO have a tapered thread which doesn't fit?

You would need an adapter which is male threads into the block with an NPT female hole for the VDO pressure sender.

The male threads would need to be M16 x 1.5 (like stock) into the block.

[Nuvo]

Is this adapter a readily available part?

[UrS4boy]

Is this adapter a readily available part?

Have you looked? I just googled "M16.5 x 1 to NPT adapter" and got several hits, including these:

http://www.egauges.com/Adapter-Bushing-1-8-NPT-female-x-M16-X-1-5-male-p/r7964.htm

http://www.threadtoolsupply.com/metric-to-npt-thread-adapters.html

[Nuvo]

Not readily available in the UK it would appear.

[UrS4boy]

Not readily available in the UK it would appear.

Bet if you can find them somewhere in Europe. In fact after a quick check on ebay.uk I found these. (You can send my finders fee through the post )

http://www.ebay.co.uk/itm/Brass-Sump...4lszR4lKT-nzHA
Item location:
Manchester, United Kingdom