Thread: oil presure warning light on

There are four possibilities:-

1. Faulty oil pressure switch - best check would be to install a gauge as well, or swap with a known good one.

2. Wrong grade of oil - This engine was designed before modern multigrade oils, and it is quite likely that the grade of oil you are using is too light. You need to bear in mind that even the worst oil you can buy today is much better than anything available when this car was sold new.

3. Worn engine, either plenty of clearance on bearings or pump gears. As long as light goes out above idling speed, no problems are likely.

4. Throttle linkage is rubbing on harness and shorting wire to switch in some circumstances.

It is not uncommon for older engines to have the oil pressure light to come on when hot and idling, but as long as it goes out when engine revs are increased, disaster is very unlikely.

Hope this helps,

John

yes it dose,
kinda confirms what i was thinking.
ill check the wiring today and try and get an oil presure switch
I have a selection of smiths guages out of a seventies rangie, i might see if i can use that.

thanks

I agree it is most likely to be the oil, or the switch so change/check them first.

If that doesn't work, the pressure-relieve-valve is probably gummed up with old oil. The workshop manual explains how to remove it and clean it - it would be wise to fit a new ball and test the spring strength as well,

Cheers Charlie

anyone know the thread and size of the oil presure switch?

Put old engine oil in it and see what happens - by old I do not mean used old oil but oil for older worn engines - Shell certainly has a product as do most other oil brands.

garry

Originally Posted by garrycol

Put old engine oil in it and see what happens - by old I do not mean used old oil but oil for older worn engines - Shell certainly has a product as do most other oil brands.

garry

yea putting penrite classis medium in it, but ill try and check the switch and have a look at the oil presure releif valve while the sump is of{have to change a stud}
thanks mark

As stated use a 30/50 straight SAE oil
or one of the following
Thin or diluted oil
Low oil level
Choked pump intake filter
Faulty release valve
Excessive bearing clearance
Excessive camshaft bearing clearance
loose or restricted oil line
can not find any other reason
have fun fixing it
cheers
Iam

Originally Posted by garrycol

Put old engine oil in it and see what happens - by old I do not mean used old oil but oil for older worn engines - Shell certainly has a product as do most other oil brands.

garry

When I was getting my S1 on the road I visited Caltex and spoke to a technical guy. He claimed the 'oil for old engines' 20W60 or 20W75 was OK for a tired Falcon or Commodore but didn't recommend putting it in an 'old' vehicle.
Extra strain on the oil pump can cause even more problems.

If it's losing pressure because of worn bearings etc.....
I ran a 1973 BSA 650 for many years back in the UK. Towards the end of the time I had it, when it was hot the oil pressure warning light came on at tickover. Never had any issues but I did get replacement shell bearings (oversize), big end bolts, crank bush & bearing ready for the inevitable rebuild. Sold it along with all the new bits still running OK.
A hydrodynamic bearing will run with a gravity feed oil supply so as long as there is still some pressure it should be OK but ultimately it's telling you that the bearings are worn, oil is flowing out too easily so you cannot build up enough pressure in the system. If the bearing shells are worn they lose their ability to collect dirt (sticks in the white-metal) so you will be getting more wear on the journals.

Hopefully a 20W50 for older engines cures the problem or it turns out to be the pressure relief valve or pressure switch.


Colin