Oil pressure confusion

[PoleDriver]

Last year I had a problem with my oil pressure (AJP 4.5). The low pressure light came on but there was plenty of pressure showing on the gauge??!! Booked her in for a service, oil changed, new filter and a new pressure relief spring. Turned out the old spring was considerably shorter than the new one! Everything back to normal.

Back to today. I took her out for a 'spirited' drive and after about 45 minutes the oil light came on again! the pressure was showing 65 at 2000 revs and went up to 75 at high revs. After a half-hour break I started up again and the light was out. 10 minutes driving later it came on again!

Any suggestions?

[ridds]

Oil pressure switch, back of the block. They fail and can be a pain to get hold of as they are made in batches.

[PoleDriver]

I'll have to check with my mechanic, I believe that this was changed. If the switch fails does it just mean that the indication is wrong and there is no actual problem?

[ridds]

The gauge and switch are 2 separate items.

The gauge will give you a slower response to changes in oil pressure. The light is there as a "Stop" indicator. However, these can fail.

If you have a prolonged lamp illumination with no change in gauge pressure then it's your switch gone again.

[gerradiuk]

Is the oil level at the top ?
If you gave it a good thrashing then the oil will be hot & thinner
so may flicker the light at lower revs, my guess is a bad earth to the switch.

[PoleDriver]

When light comes on it's permanent at any revs. Oil was checked before I went out and was full. Just checked again and is still full.

[ukkid35]

http://www.ebay.co.uk/itm/190584999695

£6 plus p&p

[PoleDriver]

[ridds]

ukkid35 said:

http://www.ebay.co.uk/itm/190584999695

£6 plus p&p

Handy! Hopefully your coil pack mounting plate and coil packs will come out OK if the switch has been changed recently.

Also, you could check the wire hasn't fallen off first.

[greenracing]

I would check the wire that is connected to the switch first. If the wire is earthing out because the plastic outer has been damaged/melted through/worn through the dash light will come on.

[ukkid35]

just swap out the switch.

I'm as cheap as hell, but even I can run to £6 (plus p&p).

While you're at it change the coil packs (if they look suspect) just £25 each for the cheap Chinese versions.

[Dazza N]

While you Guys are talking oil pressure , where should it be on idle and under load on the SP6 ? Cheers.

[optimax sniffer]

ridds said:

Handy! Hopefully your coil pack mounting plate and coil packs will come out OK if the switch has been changed recently.

Also, you could check the wire hasn't fallen off first.

Although I took the coil pack plate off when I did mine, I don't think that you have to.

[ukkid35]

optimax sniffer said:

Although I took the coil pack plate off when I did mine, I don't think that you have to.

Agree - It's shaped as if you can leave it undisturbed.

[ridds]

ukkid35 said:

optimax sniffer said:

Although I took the coil pack plate off when I did mine, I don't think that you have to.

Agree - It's shaped as if you can leave it undisturbed.

I'm sure I tried but couldn't access. Might have been my socket though.

[spongy]

access was limited on mine due to my fat belly.,and it was a loose wire on mine

[scotty_d]

Think my oil pressure switch is failing, drove from Ayrshire to Oxford today 400 odd miles via track v road for a geo set up, as I pulled in to the hotel for a nights stop the oil pressure light is flicking. The gauge is solid 40psi at tick over and climbs up when on the move. The light goes out when revs climb. Oil level is Max, think its just the switch but little worried as on route to le mans classic. Help!!

[Byff]

This is catching - my oil pressure light has come on too.

Not looking forward to digging around my mess of cables.