oil presure warning light on

[mfc]

ive got an issue where when at opperating temp i get the oil warning light come on when a/ you stop or b/ coast under no load

im thinking it may be crap multi grade oil ive been poring through the engine to clean it out {cheep 15/w 30 im only doing minimal kms between changes}

the sump has been off and oil screen cleaned etc , although im unshure of the oil presure switch as im not registered so not driving it more than a quick nocturnal buzz of 10 ks or so.

I recon its the oil, but i know bugger all............

any points to check prior to putting decent oil in her? {penrite classis medium} , really seems only to ocur with youre foot of the accelerator or under no load.
cheers mark
ps seems to run like a freight train up to 47mph{fear prevents further progress lol} handles realy well on rough dirt roads as well

[JDNSW]

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

[mfc]

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

[chazza]

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

[mfc]

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

[101RRS]

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

[mfc]

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

[back_in]

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

[gromit]

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

[incisor]

original recommendation was sae 30 oil above 32 deg sae 20 below 32deg

sae 50 is about as thick as sae 90 gear oil and is what was recommended for the gearbox and transfer cases in the early ones..

i agree with glen when he said penrite 20w-60 for the old girls power plants...

[gromit]

original recommendation was sae 30 oil above 32 deg sae 20 below 32deg

sae 50 is about as thick as sae 90 gear oil and is what was recommended for the gearbox and transfer cases in the early ones..

i agree with glen when he said penrite 20w-60 for the old girls power plants...


The 60 of the Penrite multigrade would be thicker at 100C than the originally specified sae 30 and also a 20W 50 multigrade.
I just visited their website and they push the 'extra 10' in viscosity index as a plus point for our climate. Thicker at temperature must also mean more effort to push round the engine ?

I don't know enough about oils to comment plus everyone has their own recommendations based on the fact it worked OK for them.


Colin

[mfc]

the penritte is equivelant to a 40 w,its in as we speak but it was to wet to run it last night, ill don the balaclava tonight and report back
I changed out the transfer and gear case with penrite classis 90w and its made a hell of an inprovement...heaps quieter, smother shifting.
ill telll you how it goes later

grommit.... yea i recon its worn but ive got a spare im building

[mfc]

just did the same run that would have the oil light on at power of or stopped,but with the classis oil in g box {90w} transfer and engine classis medium.....all seems sweet mutch easier changes in the box and no oil light untill you stop for 40 seconds, soon as you touch the accelerator its normal

[JDNSW]

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

Guessing - 5/16 or 3/8"BSF Not something you will find easily. I suggest you remove the switch and measure the diameter outside the threads and the number of threads per inch will identify it. But I would be surprised if it is not BSF. Once identified, you might want to consider getting or making an adapter to a more commonly available thread.

John

[gromit]

just did the same run that would have the oil light on at power of or stopped,but with the classis oil in g box {90w} transfer and engine classis medium.....all seems sweet mutch easier changes in the box and no oil light untill you stop for 40 seconds, soon as you touch the accelerator its normal

On my Series I the oil pressure light doesn't always go out until you blip the throttle. Sometimes it comes on at tickover and a blip of the throttle it goes out.
I'm putting it down to a 'sticky' pressure switch although the history of the motor is unknown.

I should put a pressure gauge in and check but I'd probably be frightened by the result !


Colin

[mfc]

same story here colin. undoughtably worn engine but with the older oil it only comes on after a spirited up hill run on dirt {as you stop} or on the flat rollling to a give way etc or pull up in driveway, any load or acceleration and its gone also speed up to 50 mph rather than 40 with all new fluids......{not terminal velocity either,i fear that}
on a positive note i mesured the bores on my other engine {new rings } and spot on spec for an unrebored engine and no lip on the top ....yay.... ill mesure the crank journels today, the bloke said they were fine{mesured} but the engine needs to come apart to be cleaned out..
...blinkers and all elecs working and minimal leaks when hot, steering seems good ,just need to touch up the brakes and find a 1955 horn....
cheers mark