TOPIC:

Just getting the 1983 A5 beast back on the road after a long absence and have a final hurdle to overcome.

Oil warning light.

All systems flushed and fluids changed and ready for MOT when...started up and the oil pressure light stayed on! So I switched off, checked oil level and had a good look around and all seemed fine, started again and light went out as normal - phew.

But next day, started up - same again.

After the fourth start when the light went out, I left it running for 10 minutes to get to operating temperature and all seemed well. Switched off, started again - light on!

It has never comes on once running, it sometimes just fails to go out after start up.

It's not an oil level problem (it maybe the switch) and I can't imagine it's a pressure problem, but I don't think it's a faulty pressure switch either, they work or they don't - right?

So ready to get road legal but I daren't ride it. Any suggestions?

The Oil Pressure Switch is merely a pressure disc that breaks contact (OPENS) when the minimum pre-set pressure is recognised. It's possible that the contacts in yours are dirty/corroded. Nothing you can do to repair. OEM's can be pricey but any generic could be used provided the pre-set pressure rating to OPEN is within the value needed and the male MPT is the same - which is standard 1/8" MPT - I believe.
Perhaps someone can confirm, but I believe the Oil Pressure Light, goes OFF with as little as 4lbs PSI.
Something like this:
allstarperformance.com/pressure-switch-4-psi-all99058/

On the 1981's and up, Kawasaki also included a oil level sensor. The Oil warning light will go on and stay on if the oil pressure is low OR the oil level is low. The 1981 supplemental on page 310 describes the system. Have a read. The "Oil Pressure/Level Sensing System" uses the same indicating light to warn of an engine oil problem.

There have been a couple of reports over the last 3 years of the oil level warning system gumming up and giving a false reading. Just saying.

What Kawboy states is correct.
I had the same issue on an A3 I owned many years ago.
The oil LEVEL sensor is inside the sump (oil pan) at the rear and is not a good design at all. You will see the wire going inside the sump at the rear.
Under heavy acceleration or braking mine would flash on and off (giving me a heart attack) yet the oil level was more than ok.
It also did what yours did on start up.
Personally, I would give it some miles and use first before investigating, as it may just need to be used to right itself.

Pete F
UK (or whats left of it)

Someone suggested washing the float sensor in petrol as that worked for them & I did that the last time I had the sump off on my ZG. That didn't work for me though You'll find that when the oil light stays on when starting, turning the ignition off then back on again will clear it. I've just learned to live with it on mine, it's very common on all the models fitted with the oil level sensor.

Kawasaki built two systems controlling the same light. One is the oil pressure switch on the right hand side of the engine which turns the light off as soon as it senses oil pressure.
The other is oil level sensor inside the oil pan at the rear of it. That level sensor is connected to a relay which remembers the low oil level when you restart the engine and turns on the oil light in the panel.
It scares one when it happens.
You can either live with it or pull the yellow cable off the sensor at oil pan.
I removed the whole relay (under rear plastic cover, green multiconnector) from my A4.
Saves some weight. Ha ha