VDO oil pressure sender issue

[1938vw]

hey guys i bought a VDO twin terminal 0-5bar oil pressure switch and replaced my existing switch. all was well until the oil got up to temperature. i noticed at first that the idiot light came on at idle and went off the second i reved it even a little and then back on at idle. i got the car home with it this way.

i decided to take it for a gentle drive down a quiet road near home to monitor what was happening, i noticed that it got worse, coming on below 2500rpm so i drove straight back in third keeping the revs up a touch and that kept the light off.

i first thought maybe my oil had thinned out from piston wash as its a kind of test engine to try out my turbo knowledge and to keep the cost down i didnt replace piston rings etc.
my oil was fine. still thick and didnt really smell of fuel.

so i put the old switch back in the next day, cranked it over light went out, tuned it off and the ignition back on, light was off for say 15-20 seconds then it came back on without the engine running as i understand it should.
driven it a few times got it nice and hot and no oil light on.
i have been told in the past, should a stock oil pressure light fail it will give a false LOW pressure reading (light on) so it must be fine.

my question is this, is the new VDO pressure switch no good or have i got this all wrong?
heres the switch i bought
http://i36.photobucket.com/albums/e16/r ... c71071.jpg

cheers ryan

[FJCamper]

Hi 1938VW,

The 80psi double-pole VDO-360-006 sender (G on sender pole indicates gauge, WK is oil warning light switch) can easily be bad. I'd had two or three bad ones over the past few years. I switched to single pole pressure guage senders, and run a standard pressure light switch off an adapter.

Oh -- don't use Teflon tape on the threads on any of them. The senders ground to the case!

FJC

[Marc]

Before you give up on the dual sender, try mounting it "upside-down" (so the terminals are pointed downward or as close to it as practical). These senders can trap a big air bubble when mounted posts-up, which can cause erratic/sluggish operation.
If that doesn't help, then the diaphragm inside is leaking internally (and the sender soon will be leaking to the outside world).

[1938vw]

Cheers for the input chaps. Sadly I fitted it without tape and it is already upside down to stop air being trapped! I may forget about the whole idea and just add a larger idiot light in there!

[kangaboy]

PIECE OF poop VDO!!!!!

sorry,
i had the saaaaaaame exact problem for a few months....i even added a new deep sump, re-clearanced my oil pump gears, used different types of oil weights. Just put on the STOCK idiot light and all my problems went away. I suggest you do the same and see what happens.

Its funny cause i could copy and paste your first post and title and it would be the same exact story as mine. No need to know your oil pressure, if you light stays off and you have a stock motor your more than likely good to go.

[HDSmkr]

I had the same problem, I ended up putting the stock sender back on and no light to date... From what I could gather is that the stock sending unit is supposed to set that light off at around 5psi and the Vdo unit is more like 10psi.

I think?

[Dangermouse]

Yep, the VDO units trigger the warning light at a higher pressure than the stock sender.

See http://vwparts.aircooled.net/VDO-80psi- ... 360006.htm

[1938vw]

It sucks!!? its out and going on ebay!!