Low Oil Pressure AU Fairmont 4L

[Bulandgoose]

Every now and again when I'm stopped stopped at the lights on a hot day, the oil sensor warning beeps and the oil light blinks. The pressure gauge doesn't quite touch the left side red bar and the reading comes back up to halfway if I touch the accelerator.
I changed the oil about 4 weeks ago. The store didn't have 5W-?? oil (?? means whatever it said in the manual) but they said 10W-?? would do, and it also said that on the oil container.
Is that the problem?

[Cam]

I would replace your oil pressure switch... They are prone to failure.. Can you hear any signs of there actually being no oil pressure? Or just the gauge reading?

[SLO247]

I agree, change the sensor.

Just ensure you get an oil pressure sensor, rather than an oil pressure switch. The switch is used in the basic Falcons with no oil pressure gauge, as it just operates a light.

I believe they are still available from Ford at a reasonable price.

[SSD-85]

Also, check for proper earthing. The gauges go all silly if you dont have a good earth.

[rowan194]

I had the same warning a couple of times in my EL Fairmont, idling in drive at a busy intersection with multiple light changes in other directions, very hot day...

The fact that it happens when you're stopped at the lights on a hot day, and revving slightly makes it go away (I did the same thing instinctively to try to bring up pressure), makes me think it's probably something you should take notice of... not just a dodgy sensor.

What series is your AU and what's the exact brand and grade of oil you put into your engine?

[mik]

done a lot of k`s? does it rattle?

[Bulandgoose]

Originally Posted by mik

done a lot of k`s? does it rattle?

No, it's only done about 240,000Ks.
Doesn't make any undue noises.
It did this just once about 7 months ago when I first got it. I found the oil was a bit low, and after I topped it up it didn't do it again until just now.
It has some sort of "active" oil leak, that is, it doesn't drip on the concrete, but it slowly loses it as you drive. (There's no sign it's burning it, the exhaust is very clean).
Since I got the car for nothing, I'm not going to be spending much on it, nice though it is. (It's still far faster and cheaper for me to catch the train to work, so it doesnt get a lot of use).
I don't see how it could be the sensor, since it always reads about half-scale when you move away from idle, no matter how fast the engine is revving.
Is there some sort of oil additive (Wynns etc) that will give extra protection if the pressure is low, or is that stuff basically Snake Oil?

[rowan194]

What series is your AU and what's the exact brand and grade of oil you put into your engine?

No point thinking about oil additives if you've got the wrong type in there in the first place!

[dieseltrain79]

My wifes car does the same thing . 150k on the clock and has ben doing it in summer since we have had it , bougth with 120k on it .

AU series 1 . Only now and then , i change oils at 5,000 and always run 5-30 in it .

I thought about changing the switch this time but wasnt sure if its a common issue .

[mik]

i would try the sensor myself, cheap an easy ones first ;), if that did`nt work i`d put a cheap capillary oil pressure gauge on the motor(0- 100 psi) and see what is really happening.

[Psi-Pop]

My motor on a hot day drops down to about 25psi on a low idle, bring revs up even 100rpm or less and pressure comes up to 40psi instantly. That's using a autometer mech gauge, so they will drop in pressure when hot and at idle.

I'm not overly concerned as its only at idle and there's no load on it when the pressures down.

[superroo]

What oil brand are the two guys with low oil pressure using?

If it's penrite, then there is your problem

Cheers

[mongrelEF]

Also, what revs are the engines doing? Are we talking very low idles, or a normal speed?
What oil levels in the motors?

[mik]

imo not really necessary to run the thin oil now, i believe they ran the thin stuff from the factory for tighter tolerances, i run mine a little thicker oil, 10/30 is recommended mine, presently running 15/40 iirc.

[david256]

My V8 does the same, Low Oil Pressure warning while sitting and after a lot of research I believe its the Volts/Alternator or gauges.

If you have a volt gauge watch the Volt gauge drop and at the same time the oil pressure drops, as my volts drop from 13.8/14 volts down to 12/12.5 volts the oil pressure drops. I suspect its either the gauges playing up or the Alternator is on its way out. Personally I think its the alternator as it plays up more when Im using the Air Con Fan on high and Head Lights.

btw I changed the Oil pressure switch/sender made no difference, so was just a waist of money.

[rowan194]

Originally Posted by mik

imo not really necessary to run the thin oil now, i believe they ran the thin stuff from the factory for tighter tolerances, i run mine a little thicker oil, 10/30 is recommended mine, presently running 15/40 iirc.

My Gregory's manual says...

AU -- 5W-30 ILSAC GF2
AU series II and III -- 10W 30 WSS-M2C-910-A2

So the grade of oil changed between S1 and S2. Which is why I asked what the OP has.

[Bulandgoose]

Originally Posted by rowan194

No point thinking about oil additives if you've got the wrong type in there in the first place!

The grade was 10W 30, which both the store owner and the label claim will do in place of 5W 30. I don't remember the brand; It wasn't one of the common ones, and it wasn't cheap. Since I needed the full 5 litres, I simply put the used oil back in the container for disposal, so I don't have the container. I'll have to go have a look in his window.
I've been topping it up with the correct grade: Shell Helix 5W-30.
$49.95 for 5 litres!
The oil on the dipstick is still very clean, looks like pale honey, so I don't think it's anywhere near its use-by date.
Just after I changed the oil I drove the car to Brisbane and back, and it never did it once on that trip.
The other thing is, it never actually drops quite down to the left red bar, so maybe the warning beeper is set too low.

[Bulandgoose]

Originally Posted by superroo

What oil brand are the two guys with low oil pressure using?

If it's penrite, then there is your problem

Cheers

That might be the brand! However, I tend to agree with Psi-Pop; it's probably not a real issue.
When you only have an oil light, you have no idea what the oil pressure is doing most of the time anyway, which seems perfectly fine for the vast majority of motorists in the world.
I have no idea what the benefit is of having an oil pressure gauge on a family sedan anyway.

[Bulandgoose]

Originally Posted by rowan194

My Gregory's manual says...

AU -- 5W-30 ILSAC GF2
AU series II and III -- 10W 30 WSS-M2C-910-A2

So the grade of oil changed between S1 and S2. Which is why I asked what the OP has.

I can't tell you off hand. I'll have to look it up.

[J.C.]

Quickly skimmed over the thread.
I'm with Cam and Mik (and whoever else suggested similiar). Purchase a gauge, tap it into the oil gallery and see what is truely happening. Grab a sensor as well and replace it if you end up finding it reading incorrectly........or just throw one at it anyway as they do fail. They are cheap enough.
Also wish to back up the suggestion of low system voltage at idle. Do not disregrade this. It is the cause of many a non existence faults and errors within electrical circuits. Leave a car or machine idling long enough and the current and voltage draw is higher then the alternator output at low RPM.
Idle speed? Is it to low due to parasistic loads such as worn and dragging pulley bearings for example, blah, blah, blah.
Heat soak plays havic with cars and stationary machinery where it's principle design was to have movement to remove heat and not souly rely on water jacket water or some ****y thermo fans.

If you can't find anything simple out of the suggestions in this thread, purchase yourself a new filter and filter cutter. Inspect engine oil filter ............with fingers crossed. Remember, inspect the outside of the filter. Not the inner area. Filters outside in, through the filter. Cut a section of the filter out once you have the element apart and squeeze excess oil out of it (use a vice if you have one available). Open it up and read it like a book. It tells a story.
My experience with AU 4L's is they are generally pretty bullet proof and screwed together well enough for a mass produced factory engine. But, like everything, they are only man made and components, sensors etc do fail.
Let us know how you go. I'm keen to hear the outcome. I sincerely hope it starts and stops with a simple engine oil pressure sensor.
Cheers.
JC

[rowan194]

Originally Posted by Keith Walters

I can't tell you off hand. I'll have to look it up.

What year is your car?

[Bulandgoose]

Originally Posted by rowan194

What year is your car?

2000

I'd get more details but the thing is parked half a mile away. (Which I why I usually travel by train!)

[Psi-Pop]

I'm using Sin 20 (20-60w). Which I'm sure most of you may freak out about but its working well for mine, coming from Edge 25-50w its a lot more stable after 5+ pulls on a dyno or a few 1/4 passes.

[5.0 ED]

Checked your earth points under neath the airbox, they cause the gauge to read low like your saying, in particular on hot days at traffic lights, the poor earth makes the gauge way over sensitive.

There is nothing wrong with running 20w-60 especially in summer.

The rule of thumb for oil pressure is 10psi per 1000rpm.

[Bulandgoose]

Originally Posted by 5.0whiteaughia

Checked your earth points under neath the airbox, they cause the gauge to read low like your saying, in particular on hot days at traffic lights, the poor earth makes the gauge way over sensitive.

There is nothing wrong with running 20w-60 especially in summer.

The rule of thumb for oil pressure is 10psi per 1000rpm.

Oho. I did actually do some work down there just recently, replacing the transistor in the fan controller. I'll look for earth leads with volts on them.
I actually had a problem very like this about 30 years ago in an XR 289 V8 if you can believe that. The temperature gauge used to read alarmingly high when you were driving along, but would return to normal when you stopped at the lights.
It turned out the engine block was about 3 Volts negative with respect to the chassis, because the block earthing lead bolts had come loose! Tightened them up, and everything was happy again.
And all of a sudden the lights were brighter, the indicators clicked at the normal speed, and the horn got a lot louder!