Technical Oil light

[LaverdaJota]

Hi,

Oil light came on today - oil level fine, car runs fine.

Read a oil thread for a diesel Panda but mine's petrol 1200. Home serviced for the past 167,000 miles & never reset anything.

Dodgy sensor perhaps (my engine warning comes on from time to time if it's a cold day)?

Thoughts gratefully rec'd.

Nick

 

[koalar]

If you have a multimeter it's easy to check

It right next to the oil filter

The switch itself is quite easy to see if it's working

It's located on the bit the oil filter screws into

With the engine off it should read close to a short, less than an ohm block to its terminal

With the engine running it should measure open

There rare to fail but not unknown


With the ignition on the disconnected oil pressure cable should measure 5V or over, again using the block for the other meter lead

 

[koalar]

I would not drive the car until it's been tested

The light could be correct and oil isn't circulating, less than 5 psi

Blocked filters, bumped sump, running with low oil pressure is going to cause more problems

Or it could just be a faulty switch or wiring, which is more likely


Is this just after cranking

"my engine warning comes on from time to time if it's a cold day"

Earth strap is another possibility

 

[LaverdaJota]

Hi thanks for the prompt reply. The light just doesn't disappear with the rest as normal. I'll get on it with the multi-metre as you suggest.
Thanks
Nick

 

[LaverdaJota]

So go out to put it on the ramps and the light ain't on no more! A self fixing car - perhaps if I ignore the fuel light it'll fill itself up!
Nick

 

[koalar]

I would do some preventative checks

Clean the top of the battery negative post
Multimeter reading volts if it's got a range selection something around 20V
Measure between the top of the battery negative and the engine block while cranking

Also check around the oil filter for leeks
And next to it is the oil pressure switch look to see if this is weeping oil

 

[LaverdaJota]

Hi, I agree with the suggestion to check about. My thoughts are dodgy switch as with m/c you tend to get low pressure warning at tickover forewarning of 'issues'. As it just came on (& went off) I'd think switch.
From memory it's damp round the filter so probably this is coming through the switch.
As ever big thanks & will report back on what I find.
Nick

 

[ultrasonic]

I have the oil pressure warning coming on for a second. It happens only when cold. It's not an electrical issue since it happens with a gauge connected instead of sensor: it takes a while for the pressure to go up. Once pressure is up specs are OK. It happens with both 5W 40 and 10W 40 oil and new oil filters. Any ideas??

 

[koalar]

I take it you have taken the switch out to use a pressure gauge


What psi are you getting at first switch on and idle


Has this started at the same time as the gearbox overhaul, it's easy to damage the dump doing this

 

[ultrasonic]

I take it you have taken the switch out to use a pressure gauge


What psi are you getting at first switch on and idle


Has this started at the same time as the gearbox overhaul, it's easy to damage the dump doing this

Thanks for the promt reply,

Gearbox issue was very recent, I have this oil pressure issue for a good while now (could be 1-2 years).

I am attaching a short video right at the moment of starting up when cold (car was sitting for a day or two). It seems that it's zero at first switch on and then directly jumps to 16-18psi, after the oil pressure warning is heard. Warning comes up 40-60% of start-ups.

I feel like it's the o-ring from the oil pickup sucking air but I don't have much experience on this.

 

[koalar]

Can't see the video on my phone unfortunately

Sorted it's 4K and does not play an my phone

 

[koalar]

Looks like the oil is draining from the filter


Are you sure it's the right part number with an anti drain back valve fitted, quite a lot of filters physically fit

 

[ultrasonic]

Looks like the oil is draining from the filter


Are you sure it's the right part number with an anti drain back valve fitted, quite a lot of filters physically fit

Yes, all filters fitted had drainback valves and matched the OEM part number. I've tested multiple brands, only Mann Filters (W610/3) limit the phenomenon. It seems manufacturers are nowadays using nitrile rubber in drainback valves which gets harder with oxidation and temperature circles. Silicone is superior but I couldn't find any filters using it. But I think this is secondary.

Another thought I had was a siphon phenomenon draining some of the oil in the filter through the oil pump bypass (if it is partially clogged). But the oil pressure at 4000 rpm gets up to 4,8 bar so I kind of doubt it.

Crud on the pick-up line mesh could be another culprit?

I was thinking of pulling the pan and replacing the oil pick-up line along with the o-ring. I am a bit hesitant though because FIAT does not list the torque specs of the pick-up line bolts and I am not sure how tight they should be.

 

[koalar]

Psi is right at idle
Psi is right at 4k

The filter is correct

Short answer no idea what's going on

I can't see it being a blocked gauze

I not the usual symptoms for sucking in air which are normally worse at idle when hot

Is the car parked on a slope
Is there any small dints in the bottom of the sump

Was anything done to the car before it failed

 

[ultrasonic]

Psi is right at idle
Psi is right at 4k

The filter is correct

View attachment 452481


Short answer no idea what's going on

I can't see it being a blocked gauze

I not the usual symptoms for sucking in air which are morally worse at idle when hot

Is the car parked on a slope
Is there any small dints in the bottom of the sump

Yes there are definitely dents in the sump and after checking the diagrams right where the oil pick-up is... Restricted oil flow! How did I miss this, thank you!

 

[koalar]

Good new we know what caused it, bad news it's still a big job

The pickup pipe to pump has a seal that can go hard, not a problem if everything stays still, but can cause problems if things get knocked, normally after a sump renewal

I'd be changing this at the same time

There's virtually no clearance on the pickup pipe, people have had problems just by jacking under the sump without some wood to spread the load

We can't tell if the pickup pipe is damaged as well untill the sump is off

 

[ultrasonic]

So I'll replace both. From what I see at mine is plastic, not metal like in the picture. Are there any special considerations? I can't find any torque specs for those two bolts...

 

[koalar]

So I'll replace both. From what I see at mine is plastic, not metal like in the picture. Are there any special considerations? I can't find any torque specs for those two bolts...

"If" is the same as the 500

Oil Pump Pick Up Tube to Oil Pump - M6 Bolt 10 newton meters

The photo is from the same engine but in the Punto, where sucking in air was far more common

The plastic is could be an upgrade, more forgiving

But that's just a guess on my part

 

[ultrasonic]

Just wanted to come back with an update.
I replaced the oil pick-up tube and had the sump hammered back into shape.
The oil light goes away very fast and some engine noise that I had which was attributed to piston slap is now gone! (was probably due to oil starvation). Also the car seems to have a little more torque now .
Thanks to this forum, and Koalar in particular, for all the help!