What colour is the oil warning light you're seeing?

Level sensor only triggers a yellow warning light, pressure switch is what triggers red.

Pressure switch failure is often accompanied by oil within its single-wire connector.

Edited 25 September, 20241 yr by Breezy_Pete

2 hours ago, Breezy_Pete said:

What colour is the oil warning light you're seeing?

Level sensor only triggers a yellow warning light, pressure switch is what triggers red.

Pressure switch failure is often accompanied by oil within its single-wire connector.

Red, very red.  This may be good news you are bringing me because a switch could be very much cheaper than a sensor. I have yet to cross-reference parts with my car's chassis number though.

Reg plate number or VIN could allow me to research things a bit for you (tomorrow).

Before ordering a part I'd check the computers aren't on a brain-fart or need resetting from the previous incident with a VW appropriate scan tool making sure the scan tool program for you model and year has been fully updated.  IF the scan tool resets anything but there is an actual fault the fault will show with warnings again immediately you start the car so no worries about driving with an actual fault.

 

It's possible to have a coincidence of possibly overfilling oil and an oil switch faulty but 1.5 litres in a near empty engine and the dipstick showing full is strange.  I'd trust a correct dipstick used correctly more than any sensor or computer program.

 

Good luck, let us know the outcome of all of this.

 

6 hours ago, nta16 said:

I'd trust a correct dipstick used correctly more than any sensor or computer program.

But only when the sump is within -1l to "stupidly overfilled". Below that you may well not get oil on dipstick.

15 hours ago, Breezy_Pete said:

Reg plate number or VIN could allow me to research things a bit for you (tomorrow).

Will try to do that Pete but today completely given over to celebrating my wife's birthday. Inexplicably she takes these anniversaries seriously. I think of mine as an intrusion.

11 hours ago, nta16 said:

Before ordering a part I'd check the computers aren't on a brain-fart or need resetting from the previous incident with a VW appropriate scan tool making sure the scan tool program for you model and year has been fully updated.  IF the scan tool resets anything but there is an actual fault the fault will show with warnings again immediately you start the car so no worries about driving with an actual fault.

 

It's possible to have a coincidence of possibly overfilling oil and an oil switch faulty but 1.5 litres in a near empty engine and the dipstick showing full is strange.  I'd trust a correct dipstick used correctly more than any sensor or computer program.

 

Good luck, let us know the outcome of all of this.

 

Thanks, nta.

4 hours ago, Paws4Thot said:

But only when the sump is within -1l to "stupidly overfilled". Below that you may well not get oil on dipstick.

Thanks Paws. Nice to know you're still watching the progress here

On 22/09/2024 at 22:40, somean49 said:

I shall try to address all these queries and apparent discrepancies; but I can only say what I did and what I have seen. I know nothing of internals of the engine. I have owned the car for 11 years and do all my own maintenance.

1. I tried to change the oil [all references are to engine oil] before a long hard trip on holiday.

2. Because of disability I was unable to drain by the sump plug [this was replaced some years ago by a brass drain valve] I resorted to a Sealey Siphon TP69; and got out what I supposed to be about 3 litres.

3. Knowing the oil capacity to be 3.5 litres I introduced about 3 litres of fresh oil of the correct grade.

4. I set out on my trip. After about 100 yards the oil light and alarm began. My wife busily checked the handbook and internet for explanations while I negotiated traffic in South London.

5. As soon as possible I returned to base abandoning my journey until I could hire a car to continue on holiday.

6. 2 weeks later I returned and enlisted the help of a friend and mechanic. The TP69 was again used to extract about 3 litres of oil. The mech then jacked up front nearside of the car for access to the drain valve. About half a litre was drained.

The dipstick showed 'clean'.

7. I measured 2 litres of oil into a jug. I poured almost all of that into the engine. The dipstick shows overfull, ie the oil level is beyond the hatched area. It remains there. The TP69 will no longer enter the dipstick tube to the bafflement of Sealey Tech and me.

8. In desperation I started the engine today in neutral. (?I imagined something was blocking the oil galleries) I revved up to +/- 2000rpm whereupon the alarms started again.

9. This remains the state of play as of 6.30pm : the dipstick shows overfull and the alarms begin on revving the engine.

 

What is the missing component?

 

 

Respectfully, IMO it's time to stop faffing around with it yourself.

Take your car to a garage you trust and ask them to drain all the oil out, and put the correct oil in to the correct level.

Then ask them to see if there is a problem with your oil warning system and go on from there.

9 hours ago, EnterName said:

Respectfully, IMO it's time to stop faffing around with it yourself.

Take your car to a garage you trust and ask them to drain all the oil out, and put the correct oil in to the correct level.

Then ask them to see if there is a problem with your oil warning system and go on from there.

I have wanted to do that for the past few days but I am unwilling to risk damaging the car further by driving it.  My mechanic friend works a short walk away and should be willing to do this work - at price of course.

On 25/09/2024 at 18:12, Breezy_Pete said:

Reg plate number or VIN could allow me to research things a bit for you (tomorrow).

Reg is:

   SL10 GDU

29 minutes ago, somean49 said:

I have wanted to do that for the past few days but I am unwilling to risk damaging the car further by driving it.  My mechanic friend works a short walk away and should be willing to do this work - at price of course.

It sounds like it's stressing you out @somean49, so just pay the man to sort it out and throw that dead cat in his garden, as it were.

46 minutes ago, EnterName said:

It sounds like it's stressing you out @somean49, so just pay the man to sort it out and throw that dead cat in his garden, as it were.

You are definitely correct about the stress.  To ensure my family had the outing I had promised them for the wife's birthday I had to hire a car. A Merc CLA automatic. Not terribly comfortable for a car of that (supposed) quality.  And bloody expensive to hire.

1 hour ago, somean49 said:

Reg is:

   SL10 GDU

Pressure switch is on gearbox end of the engine, by the looks of this vid (see at around 1:30). Green plastic body with single wire connection.

https://youtu.be/3XXI-kpis4c?si=5NGqHCpaU-5dgx0F

Any traces of oil inside the detached connector would have me replacing the switch, part number is 03C 919 081.

 

0.3 to 0.6 bar? 😕

 

One or the other, - but both?

Hysteresis, I expect.

I'm sure you're familiar with the idea,  but for anyone not, this describes it in the context of  microswitches

 https://my.avnet.com/abacus/resources/article/understanding-micro-switches-and-hysteresis/.

 

Oil pressure switches and thermoswitches are variants of the above, I think. You tend to see more than one number quoted in both cases, a 'turn on' value and a 'turn off' one.

Edited 27 September, 20241 yr by Breezy_Pete

Yes very familiar, just surprised that it should be so consequent, mind you with electronic thermostats accurate to 1/10 of a degree Celcius having 3 or 4° of hysteresis I should not be surprised.

 

Thanks for pointing it out, I've never seen both numbers quoted (I sourced lots of super low pressure switches for race engines) but agree that must be the case, its good that they show the thresholds.

That was a good video (apart from shot in portrait instead of landscape) and if in somean49;s case it doesn't turn out to be the oil pressure switch at fault or there's another issue in addition to a faulty oil pressure switch I have another possible idea.  Using a screw in pressure gauge is a good idea to check the switch regardless, especially if mechanic mate is going to charge for his time and labour.

Actually on reflection its probably designed to have a higher hysteresis than a traditional oil pressure switch, that way it would switches on and remain on and not flicker at idle with hot oil.

13 hours ago, Breezy_Pete said:

Pressure switch is on gearbox end of the engine, by the looks of this vid (see at around 1:30). Green plastic body with single wire connection.

https://youtu.be/3XXI-kpis4c?si=5NGqHCpaU-5dgx0F

Any traces of oil inside the detached connector would have me replacing the switch, part number is 03C 919 081.

 

Well worth watching, thank you. And the advice is welcome too

8 minutes ago, nta16 said:

That was a good video (apart from shot in portrait instead of landscape) and if in somean49;s case it doesn't turn out to be the oil pressure switch at fault or there's another issue in addition to a faulty oil pressure switch I have another possible idea.  Using a screw in pressure gauge is a good idea to check the switch regardless, especially if mechanic mate is going to charge for his time and labour.

Which tool I luckily have from my earlier incarnation as an inveterate fiddler.

While searching without success for the VIN (online as well as in an extremely disorganised 'Steptoe & Son' heap of documents) I found this plate under the bonnet to add to my worries:

VIN can be discovered by entering your reg number at chipex.co.uk and reading from the resulting URL at the top of the page (may need to scroll across the length of it).

Also visible through windscreen from outside, just below passenger side wiper,  generally. 

9 hours ago, somean49 said:

Which tool I luckily have from my earlier incarnation as an inveterate fiddler.

In that case if your mechanic mate don't bring his charge him to use yours. 😄 

 

3 hours ago, somean49 said:

While searching without success for the VIN (online as well as in an extremely disorganised 'Steptoe & Son' heap of documents) I found this plate under the bonnet to add to my worries:

Yeah but you hardly drove it like that.  Another reason, among many, as soon as possible, to take the car for a good extended blow-out run and get the engine fully warmed up and give the car's mechanical systems good stretching exercises, blow out from intake, through engine and out the back get rid of the cobwebs and anything else.

 

For VIN on paperwork in the paper piles (a system I now use on the real-life desktop to match my wife's system of papers everywhere, Covid has a lot to answer for) any bill from a Dealership, or it's on your V5C (important paper documentation I keep in files, backed up as all this paper is a fire hazard 😆).

 

Edited 27 September, 20241 yr by nta16

Cheers nta. The paper is always at risk with my cooking skills. As soon as weather permits, my mech mate says, he will crawl about underneath to complete what he hasn't finished. Then he and I can take it from there.

And thanks to Breezy Pete. It's extraordinary what one forgets. There was the VIN staring at me. Perhaps I should clean the car more often.