just been driven the ute around, and every now an then at low idle the oil light just comes on, there is plenty of oil and the filters new. what could cause this? its only the oil light

low oil preasure

Ditto

yeah that or the oil pressure switch could be stuffed also could be that the oil is 2 thick maby?

the oil switch is rather new, only a few months. i did an oil change on it about a month ago. and the oil i use is the same as always. whats it mean if its low oil pressure, as in wat needs fixing? it also doesnt come on all the time, and as soon as you give it a lil rev it goes off

Low oil pressure = ####ed oil pump! At least their easy to get at on a A series! Maybe get the oil pressure checked or do it yourself if you have a guage. Could be the wrong switch and coming on to early.

When you start it from cold does the light stay on for more then usual (5-10secs)?

Sounds like the pressure relief spring is getting stuck, so the pump can't build any oil pressure. As soon as you rev the engine, it unsticks & oil pressure comes back. It used to happen all the time with my race engines til i found a source of new oil pumps. So you can pull the pump apart & give it a could clean out, or fit a new oil pump.

This will also happen if your bearings are worn. Particularly if you've given it a hard time or driven it on low oil. Hope its not but it is a possibility!!

Quote:
Let me see if I understand, you are saying that if the oil is too thick, then the oil pressure could drop so low at idle that the oil pressure warning light comes on, but the oil pressure will rise when the revs rise & the light goes out, ....... with oil that is too thick.

Now I'm always up for learning new stuff, so perhaps you could explain the physics of how that could come to pass, because the logic of it completely defeats my tiny brain.

Looking forward to your simple yet comprehensive explanation.

I had a situation a while back where the 1200 engine in my wife's car was doing the same thing. I had reconditioned the engine within the previous 6 months & everything in it was new. There were no undue noises from the engine & it ran as sweet as you could wish.
I replaced the pressure switch & then the oil pump with new.

Eventually I switched a spare engine into the car & steadily dismantled the 1200 engine to find the cause.
I didn't need to look far as I found something strange in the sump. It was the rearmost camshaft bearing. These bearings had been replaced during the recondition job & the rear one must have been loose in the bore. It was presumably pushed out with the oil pressure from the welch plug side. Every time the rearmost cam lobe went round it reformed the bearing to lie flat against the back of the block until the whole thing eventually fell right out.
We put quite a few thousand miles on it with the last part of the camshaft completely unsupported at the rear end.

It was replaced under warranty & the engine was reassembled & reinstalled to give many years of reliable service after that.

The only symptom was the red light at idle, .... now that's Datsun tough.

haha yeh it is Datsun tough. Becuase when that happens to the commy V6 they snap a camshaft because it seizes the far end of the shaft while the chain keeps driving the other half.

Lets hope its not that severe this time!