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.