The red warning lamp of death. Game over?

[mk2]

You probably know which one I mean. The little oil can symbol. Flashing and beeping away while I was driving earlier. To be investigated, but I'm hoping it's the oil pressure switch. Else I've driven a few miles with NO oil pressure. 

Yeah, I pulled over straight away, with a lump in my throat. And a fair bit of cursing. Oil level perfect. No oil leaking anywhere. Oil filler cap covered in a good layer of oil- not dry. There's no quick way to know if there's any oil pressure. Oil and filter change only about 1500 miles ago.

But the wierd thing, is that once I switched off, and then restarted, the oil light went out. i let it idle for a minute or so, no light. All good. So drove off again. As soon as I hit about 1600rpm light came on again. And repeatable. So i drove with the engine revving under 1500 just in case.

So my hunch is either a dodgy pressure switch (hopefully) or maybe a stuck oil pump pressure relief valve. The oil going through the pump and relief valve is unfiltered, so it 'is' possible...

Thoughts?

 

 

[tchouki85]

hello indeed there is a problem somewhere, can you tell us the motorization of your Lupo please, then if it is a diesel I think that makes you look at the side of the connectors of your oil sensor which is  at your oil filter support

[decvalts]

Is this your SDI? Hope it's just the pressure switch! What's the mileage on it out of curiosity? 

Edited February 20, 2023 by decvalts

[mk2]

Yeah, one of my SDIs. 100k miles. Just run in...

Not the oil pressure sensor. Swapped it over with one from the other car. Same.

Exact same symptoms. Start, run, idle. No problem. All smooth and quiet, as normal. Rev the engine up to about 1600 then the oil light starts flashing and beeping. Back to idle, still flashing. Keeps flashing until switch off. Engine sounds the same when driving- no extra noise or smoke or anything. Everything feels and sounds normal.

But...

Yesterday, it stopped flashing and now everything is normal. No oil light at any RPM. What??? Can't get the oil light to come on again now, except when the engine is not running. Very strange. I have a feeling it was the oil pump pressure release valve. When oil pressure release valves open, they sometimes stay open and don't properly close until the oil flow completely stops. Same can happen with power steering pumps.

Question- if there is no oil pressure, how long does it take for the hydraulic tappets to start making a noise? They leak away slowly when you switch off, but if there is no pressure when running, they must slowly empty? I don't know. When the engine is hot, the oil is more runny, so maybe they empty quickly. But i didn't hear any tappet noise. I wonder if it is an electrical problem? Instruments? Loom? Main engine connector? Instrument connector?

[Trims]

I had a similar issue a couple of months back with my SDI. Restarted, light + buzzer returned initially, but now nothing.  Nothing logged on a basic OBD2 tool.

I understand it’s a single wire on/off switch system that doesn’t go through the CPU.  Initial light on and off is apparently a systems check (how?).  

Potentially could be either an actual low pressure issue (mechanical) or the system thinks so (electrical).  

Methinks oil pressure relief valve should open when the oil is cold (despite being, say, 10/40) but closes and stays closed once warmed up with the oil thinning.  Mine had been run a number of hours before light came on so hopefully would have already been closed for a while.  Suggest if it sticks open it would show symptoms when partially warmed up.

Tappets - would have thought the valve spring pushing against the cam will try and empty the bucket when there is no oil pressure and the engine turning, so as a total guess maybe within a minute or so, say by the time you’ve pulled up.

Contamination fleckles on the oil side of the switch (or in the gallery) can apparently cause switch malfunction.  

Wiring - loss of signal is a potential.  The loom underneath the battery tray is apparently a place to look, but I would have thought any of the connections in a hot engine bay also.   Has been suggested to run direct from switch to dashboard if needs be.  

Agreed the first port of call would be to change the switch and see if that sorts the issue.  Should go out with extra rpm potentially.

[mk2]

I like the analysis. Hmm. Yeah, I think the same, that it's (was) just electrical gremlins. Hasn't happened since. A least I hope that's what it was.

The oil pressure relief valve on all engines opens as soon as running oil pressure is reached, and stays in a state of partially open depending on temp and RPM. 

[Skezza]

I had it beep once or twice on my SDI. Usually right on starting the car for some reason (oil was never low). Never stayed on though.

@mattarosahad a Lupo 1.0 which had it intermittently for a while without engine failure. Maybe a dodgy design?

[mk2]

My other SDI has now the exact same thing! What is going on? Scares the cr@p out of me.

Here's what happens- So start hot engine, gradually rev it up in Neutral. When you hit about 1700RPM, all the warnings start going off. Exact same when driving- hit 1700, in any gear and all the whistles and bells and flashy things go off.

After lots of investigation in the first SDI, I couldn't find anything. It just went away after about a week.

I don't like it. What's the point of a warning indicator if you just ignore it?

Conjecture- I wonder if a failing alternator causes spikes to be induced on the oil sensor wire? On my first SDI with this fault, the alternator light started doing its thing about two months after the oil pressure warning thing (the alternator is close to failing IMO). They all fail in every vdub/audi/seat/skoda at around 125k miles. Usually the brushes have worn out.