Red oil warning light flashing

[Madmaninshed]

Hi, can anyone help me with this problem please?
our van has just been fully serviced, including new oil and filter. Total mileage is a genuine 56K miles.
Yesterday, we travelled about 100 Km, and very occasionally, I noticed the oil warning lamp do one quick flash.  I thought I was imagining it, but it happened again. Then, the warning light flashed continuously.  We stopped, and I checked the (by then, very hot) oil.  It seemed ok, so we drove the last 15Km home. The light did not flash again, and we made it.
This morning, I checked the oil, and it is mid way between the high and low marks. The van has a Brickwerks dash PCB replacement kit.  Can anyone advise things I should check please?
Many thanks.

[pirate-pete]

Obvious suggestion (and one I used to sometimes see in my old van on bumpy roads) but is there a loose connection behind the dash?  Your wired  in PCB replacement should cut down on the chances of that though and living in France you won't come across as many potholes to shake it too much as we get here.

Next thing is your oil too thin?  You want no thinner than 15W40 and if you don't drive in cold winters maybe even go to 20W50. Modern cars tend to use much thinner oils than we used to use in the 70's and 80's so they are not really suitable for our engines.

Some of the vans - I'd guess from mid 80's on have a fancy oil warning buzzer.  Lift the cover off your dash clocks and see if the PCB feeds some little circuit behind the speedo at the top.  Early PCBs I don't think cover the speedo, but on the later ones the PCB does stretch over to the speedo. Some of the later ones don't have the connector on that part of the pcb so will just be a simple oil warning light but if there is another secondary pcb connected to the main flexi one behind the speedo then I think that should warn you if you have a serious problem.  I can't add too much there about how it works as my old van did not have this and my current one seems to have had the dash swapped out for a lesser spec petrol one without the circuit board nor tacho etc.

Search for "T25 Buzzer of Doom" for more info or try this thread buzzer of doom and I see the advice there is to get  the oil pressure checked.  

[Madmaninshed]

Hi Pirate Pete,  The oil is new Castrol GTX 15W40.  I thought the occasional warning lamp flash might be a connection issue, but then it flashed continually, so now I’m not so sure. I will do as you suggest and check the pressure.  I prefer to do everything I can myself, after my ex mechanic burst the original radiator with a vacuum pump. Not sure if I have a buzzer of doom. I think Brickwerks may have added one after my dash pub was supplied to the previous owner. Cheers.

[pirate-pete]

If you go to top of the page and click on downloads.  Then under the technical section click on the link for Electrics Instruments it should open the Bentley chapter for the instuments.   Scroll down to page 90.22 and it will give you some info and a troubleshooting guide.  I see that page mentions the light flashes with the buzzer of doom circuit. You also say yours is flashing so that may be related.

That page is for petrol 1986 on but the circuit will be similar for diesels if that is what you have.

As I mentioned before my van does not have this feature so I think on mine the LED just acts as a simple low pressure warning so lights continuously if no oil pressure as there are no fancy electronics to make it flash. So on mine if ignition is on and engine off my oil light stays on continuously.  If yours does flash with engine off then it would suggest you do have the buzzer of doom fitted so the troubleshooting guide may help.

[Madmaninshed]

Thanks Pirate Pete,  The light flashes on mine with ignition switch on, and goes off after about 4 seconds (without starting the engine).  It would seem that we have the buzzer of doom I will have a good read of the troubleshooting guide this weekend.  We’re doomed we’re doomed…..or hopefully not Thank you for all the information - really appreciate it.

[silverbullet]

Electrical instruments are as good as their earth returns. High resistance at the terminals can upset the warning system and give false alarms, not forgetting that there are 40 year old electronic components such as capacators that will now be well beyond their design life.

[Madmaninshed]

Quick update: I ordered 20W50 oil, but this afternoon, we took the van for a short drive.  On came the oil light.  It just flashed occasionally.  Then it came on constantly. If I stopped and restarted the engine, it went out for a while. The next time it came on, I bashed the top of the dash, and it went out immediately. This was repeated several times. It seems to be a loose connection - just got to find it…….phew!!

[Madmaninshed]

Hi, Has anyone fitted one of these please? It seems rather cheap….
Story, the picture seems rather big.

[pirate-pete]

That does look cheap for what it is

Previous owner of my van fitted a similar one but it is by VDO and has an analogue display.  Those cost a lot more and the sender unit itself is more than twice your complete package is. See VDO sender.   

I have a diesel and this sender unit  goes into the back of the head.  The Brickwerks link suggests it replaces the blue sender but whoever fitted mine used a T-adapter so I still have the original blue sender for the dashboard oil light.

If you have a place to put the gauge then go for it at that price.  The advantage of yours is that you have the digital display.  With mine the gauge reads mid scale when oil is cool but once warmed it settles to 2 bar or whatever is normal for the JX engine the reading pretty low on the scale so not easy to see if it is the needle is showing a normal reading or one too low.

See this write up to if you have a JX engine https://brickwerks.co.uk/tech/t3-techni ... -switches/.   That shows the pressure for most engines should be a minimum of 2bar but for a JX it needs to be at least only 1 bar.  That is quite close to the 0.8bar reading your gauge will start flashing to warn you of low pressure.

[Aidan]

Hi, Has anyone fitted one of these please? It seems rather cheap….
Story, the picture seems rather big.

pic is not visible in the UK so we can't see what it is

[pirate-pete]

Here you go Aidan - he posted a screenshot from French Amazon to this  https://www.amazon.co.uk/Vega-Pressure- ... B07HWYR8X3at a cost of 29.90 Euros.

Even cheaper over here on UK Amazon at £23.80

[Aidan]

dirt cheap but obviously meant for fwd car and not really clear if there is a NPT to 10mm parallel thread adapter, but the sender might not fit without a extension remote hose, so there will be a bit to do to make it work in terms of fitting and wiring

the banging the dash fix suggests it's either a poor contact on the 14 pin connector, likely because the supporting frame for the plug is missing, or the previous repair(s) aren't great - I'd always repair the original stuff so that it is all reliable and just do a wet gauge test to confirm op is okay if in any doubt

[Madmaninshed]

Hi Aidan, Thanks, I reseated the connectors, and so far so good
Took it for a run, and no flashing light. I ordered the oil pressure gauge, and will post how it goes. A mechanic friend suggested that the standard warning light on many vehicles tends to come on too late, after damage may have already occurred.  The gauge should flash all the LED’s earlier I believe.

[Aidan]

the non buzzer of doom oil p set up was a bit too late to the party, as the low pressure switch is only like 4psi - hence VW came up with the dops set up which is checking you have 1.8 bar of oil pressure at 2000 rpm in a wbx or 1.4 bar in a oil burner, which is plenty of headroom, long before engine is damaged in real world driving
the 0.9bar sensor is a bit low - it was meant for tired old engines to stop peeps constantly coming to the VW dealer worrying about the oil light