Club 80-90 Forums

OK, this one will bound to confuse you...

I have an '84 water cooled, 1.9l T25 Westie.

It runs a dream except every now and then the oil pressure warning light comes on when idling. It can go weeks without happening and then do it for days in a row. Then stop again for weeks. It never happens on cold. And most of the time will go away if I let the van cool for 20 mins.

(now the confusing part)

When trying to investigate the problem today, I found the lower pressure switch (by the push rods) has no wire connected to it. But the upper pressure switch does.

The van had a new DG engine put in 4 years ago by the previous owner at a VW garage. So I am assuming that the vans initial wiring (as its a '84) allowed for one pressure switch but the new engine had 2.

The wire is blue/black and then converted to brown as you would expect.

If I disconnect the top switch then I get no light on the dash on start up.

If I connect the wire to the bottom switch I also get no light on the dash on start up.

So my question is 2 part:

1. Why am I getting this random low pressure warning?

2. Is this engine wired up correctly considering it has two switches and only one wire?

Last point - I know the system works as I had a major oil leak problem when I first got the van and the warning light alerted me to it.

Help!

Hopefully you know switches are opposite
low pressure closed with no pressure and connects to blue black wire
high pressure open with no pressure which is your case should not be connected
connect the right switch and report back

Light should come on before you start (low pressure switch closed) then go out once started.



do check the switches with a multimeter, dont assume which is which by location or even colour, they can be fitted in either location and old switches are not all colourcoded

Itchyfeet I knew about the switch types but did not know that the location did not matter.

Light always comes on before I start then goes out once started. This is with the blue/black wire connected to the switch to the front of the engine.

If I try to connect the wire to the switch by the pushrods then I get nothing on the dash.

I had always assumed the pushrod switch was for low pressure and the other switch for high pressure.

CJRW42 wrote:Itchyfeet I knew about the switch types but did not know that the location did not matter.

Light always comes on before I start then goes out once started. This is with the blue/black wire connected to the switch to the front of the engine.

If I try to connect the wire to the switch by the pushrods then I get nothing on the dash.

I had always assumed the pushrod switch was for low pressure and the other switch for high pressure.

Push rod switch is usually low pressure and would be blue if you bought this one
http://www.brickwerks.co.uk/index.php/t ... -blue.html" onclick="window.open(this.href);return false;

but as said you dont know what switch is where so look at colours and measure with a multimeter

if the light comes on before starting chances are you have the right switch
if its showing low oil pressure then believe it and get the pressure checked or do it yourself

https://club8090.co.uk/forum/viewtopic.p ... e#p7960032" onclick="window.open(this.href);return false;

Thank you

really useful info -
how would you 'measure with a multi meter'?

edoh wrote:really useful info -
how would you 'measure with a multi meter'?

Set your multimeter to ohms or resistance then with the engine off take the wire off the switch and measure* resistance to ground/body, some meters have a buzzer which can be set to buzz with zero ohms or closed circuit/connection, same thing, conversely high resistance is open circuit

*we are talking one probe on the switch centre connection and one probe on the body, either way around polarity is not important with resistance

the low pressure switch should be closed circuit or low ohms or zero or buzz with the engine off, the high pressure switch is the other way around high resistance or open circuit with the engine off

ok so you may not want to be under the van with the engine running if you value your life so get a spare length of wire and a crimp spade on the end and connect it to the switch, then start it and check again to ground/body, the switches should change state, i.e the low pressure switch is now open circuit/ high resistance and the high pressure switch closed circuit i.e connected to ground so meter should buzz or show zero ohms

its not electrickery really

it is - til someone explains it as clearly as you

many thanks

I tested the high pressure switch which all seems to be working as it should (except it is the only switch connected to the dash)

The low pressure switch gave me nothing and so I ordered the recommended replacement part.

Once it arrives I will fit it and connect the wire to this switch.

Assuming this then works. What should I do with the high pressure switch which will now have no cable running to it. Leave it unconnected?