Club 80-90 Forums

Had the van for five years, never a problem. Regularly serviced, etc. 2.1 petrol.
Haven't driven it for a week or so, so went to take it for some petrol, prior to the MOT. Drove about 200 yards and the Buzzer comes on, with the flashing oil light. Never seen or heard this before. Went home, checked and topped up the oil (it was a bit low), then tried again. Got a bit further this time - maybe 400 yards - and it starts again. Buzzer and flashing light. What's this all about then?
I know that light flashing with buzzer means low oil pressure, but why would it go off all of a sudden, when the engine is cold?
Seems unlikely to be a wiring fault either, as it doesn't come on straight away.
Any help gratefully received.

wire to the sensor between the pushrod tubes come adrift?

mrhutch wrote:wire to the sensor between the pushrod tubes come adrift?

Nope, the wire across the top to the sensor near the oil pump either become brittle and broken or the terminal come off. Possibly the twin connection near the black box become gnarly and horrible.

Ian

Well there will be many forum members who will know more about this than me. But having recently discovered that the Buzzer of Doom oil pressure switch lead has been deliberately grounded since I have had the my 2.1 DJ WBX - some ten years , I am starting to take an interest in the dark art of WBX electricks.

I did read in my Bentley's manual that the Buzzer of Doom box of tricks - not sure where it resides - takes it's input from more than one source - one being a registering of over 2,000 RPM from the ECU and another being the pressure switch (closes at 0.9 bar) low on the front (back of the van) of the engine.

The reason for the the delay might therefore be that the engine hasn't reached 2,000 RPM yet or that there is a deliberate delay in the circuit to reduce spurious activation.

I would be interested to know if the normal red oil warning light (opens at something like 0.3 bar) - which I believe takes it's input from the pressure switch under the left pair of cylinders - goes out immediately on starting the engine. I would be reluctant to drive the van should this light fail to extinguish as soon as the engine kicks in.

Let's see what the forum experts have to say though:

Mr Bean wrote: The reason for the the delay might therefore be that the engine hasn't reached 2,000 RPM yet or that there is a deliberate delay in the circuit to reduce spurious activation.

It has to reach a certain RPM before it's triggered.

Ian

It's pretty unlikely that the oil pressure is low on a cold engine, so more likely wiring.

There's a wire (should be yellow) that goes to the oil pressure switch near the fan pulley.

The buzzer only operates when the engine is doing over 2000 rpm, if you earth the lead to the engine (dizzy probably has a spade on it) this should defeat the buzzer, so it doesn't sound at all.

If that's what happens, then you have narrowed down the problem to either wiring or the oil pressure switch itself

Have a read here - http://forum.club8090.co.uk/viewtopic.php?f=39&t=163521 not from the beginning, but from the point where I recommissioned my DOPS system.

Can you confirm that on idle the oil pressure light is not illuminated (if it is on a cold engine switch the engine off) - this works on a different pressure switch

I can see the wire, but the sensor has so far eluded me. Are they particularly well hidden on a Syncro?

From bigbadbob76's post in the thread above

You can see the fan pulley in the Samba post, top right, I don't think they are different on a syncro

bigbadbob76 wrote:Hmmm......
Comparing the one on "the samba"



With mine...



It dosn't look like mine ever had a sender there, but it's a b suffix engine in a 1986 van, and has the yellow wire that someone has earthed.
I'm confussed dot com.

Unless someone stripped the thread and welded up the hole.

I would clean off the grot and see whats under there.

FYI, there are no "sensors" on a wbx, just a few passive senders (variable resistance for temperature) and some switches (such as those for oil pressure)

Both need a good earth return at the engine (earth strap to chassis) and the instrument pack (earth crowns) to function correctly.

The oil pressure lead on the switches (brown) is prone to the crimped terminals in the white plug going green with corrosion, causing the buzzer to sound in error due to poor continuity.

Sent from my S60 using Tapatalk

Sounds like a job for the weekend. I'll dig out my little wire brush.
Am I right in thinking that if I earth the sender wire to the spade on the distributor, and the buzzer stops, then the fault is in the sender?
But doesn't that also mean that if the fault is in the wire, then the buzzer will still sound?
And if the poor connection is somewhere else, it will still sound?
Just trying to work out the variables...

Yep, earth the sender wire on the dizzy and the DOPS/ buzzer function is defeated. It thinks oil pressure is good.

Yep, If there's a fault in the wire meaning that placing the wire on the dizzy isn't actually creating a circuit to earth, then DOPS buzzer will operate (above 2000 rpm), and you will know that it's a false warning.

You test the wiring by earthing / not earthing the wire and revving above 2000 rpm

Easy things first though - find the pressure switch and make sure the connection is good, as Silverbullet said above

It'll probably take longer to find the oil pressure switch than test out the wiring

I have all of this do to restore the wiring on our Doka WBX after some clown earthed it out...

Same clown earthed mine out and cut the tacho feed signal too

Found the sender, but had to undo the alternator belt to get at it. The connection seems good (and it had a cover on it), now I’m trying to earth it. No spade on the distributor, so trying to find somewhere else. Cable looks a little worn in places, and the casing seems to have melted at one point, but appears to be sound.

Does it have to be a fixed connection to earth? Could I hold it to ground, then move it away, then put it back, etc?
Sort of switch it on and off?