Blackbird BEC - Oil pressure warning

[RogNeedham]

Just changed the oil in the BB. Used 10W40 Rock Oil Semi Synth. Put 3ltrs in to start and removed the plugs to crank the engine. The Stack dash seems ot be playing up, but cranked the engine for c. 1 min.

Just been out for a quick run round the block. At idle everything is ok, but once revs rise, the digital read out on the Stack reads 'Low Oil Pressure' and the numbers are down at 0-7psi!! Red warning light also comes on. As the revs fall (idling at lights etc), pressure warnings disappear. 

Car ran no problems at Cadwell last year - no warning lights etc across a full day.

Just wonder if the Stack / sender etc is playing up? thoughts ?

Booked in at CP on Friday

Rog

[Jonathan Kay]

Read the sensor directly with a multimeter: that should tell you whether the output of the sensor thinks the pressure is dropping or whether there's something funny happening with the electronics. If the former it could be genuine or a fault in the sensor.

Do you know the part number or anything else that would identify the sensor?

Jonathan

[RogNeedham]

...should have added to the above. Topped up oil further to 4.25 ltrs. Oil level hot at about 1.5 inches above the baffle plate, 3 mins after switching off engine

Rog

[RogNeedham]

Thx Jonathan,

I've sorted out the stack buttons now, so with the Stack readout set on Oil P & Oil T, at idle pressure reads 0. I left car warming up for 6 mins at still the pressure read 0. Raising the revs gradually to c.4-5k and the Low Pressure words light up, red light comes on and it reads c.6psi

off to do some more tests

Rog

[Ivaan]

If you had a friend with another Blackbird ( NC ), with the two cars stood side by side, couldn't you use a temporary extension wire to feed from the sensor on one car to the Stack on the other, and vice versa?

Then you'd find out which was faulty.

 

[Nick Chan]

No such fancy stuff on my blackbird. It doesn't even have a pressure gauge just a light - what more do bikers want!! :)

[elie boone]

Is the oil for motorbikes ? that would make a difference if not, also for the correct operation of the clutch

[bluenose]

Did you put all 4 litres in?  Changed the oil on mine, i.e. Drained dry sump pan and reservoir by detaching bottom hose.  Refilled with 4 litres and it is fine.  Done Brands GP trackday and oil pressure was good.  Should only drop to 15psi on idle when really hot.  When I do the oil change I remove the LT leads and crank it for a few minutes before reconnecting and starting.

Nick

[bluenose]

Ah sorry just read your second post.  4.25 litres should be fine if you did not empty the oil cooler.

 

[RogNeedham]

Well a new pressure sender hasn't done the trick either*mad*

[Jonathan Kay]

New one behaving just the same: indicated pressure falling with increasing engine speed?

Jonathan

[charlie_pank]

That is not ok.

Oil pressure should rise with revs.

I know it's not the same engine, but my R1 is up around 100psi (really!) read on a mechanical gauge.

If it was not like this before you changed the oil, id be inclined to suspect you disturbed something to do with the gauge when you did the oil-change. Any other instruments going weird? Earthing problem?

[Jonathan Kay]

Let's start with something relatively simple.

Does it have a bike-type charging system? What's the battery voltage at tickover and at the engine speed where the indicated pressure has dropped?

Jonathan

PS: Here's a very complete process for investigating charging problems on bike engines.

[p.mole1]

Whilst on the point of oil you should be careful using car oils in bike engines with a wet clutch because of the friction modifiers in car oils.

It may cause the clutch to slip,assuming its using the standard blackbird clutch

[RogNeedham]

thank again guys...sorry for the delay. Decided I had to abandon the BEC and get the SLR ready for CP last Friday.

Just to recap:

New pressure sender fitted and I'm getting the same problem. 0 PSI indicated on Stack at idle - red warning light on Stack comes on as revs reach c.4k "Low Pressure'

I called Rich Price who guided me through another instrumentation check by removing the main Stack connector from the dash. Based on the readings, he believed the instruments to be ok, particularly with new sender fitted and oil present at the sender. I did not previously disconnect the Stack, so struggle to see how previous actions may have resulted in problems.

I also re-drained the oil from the DS tank to check the hoses that had been removed were free from blockages etc. Nothing found. Hoses can only be reconnected in the right sequence due to the length of the hoses and the 'directional' nature of the JIC fittings.

So....Rich suggests the fault could be a jammed / open pressure relief valve

great fun......

Rog