Odd oil pressure gauge indication

[Hilux]

Took the old girl out today (1st time in a month as I`m so busy) and gave her a damn good thrashing to blow out the cobwebs. Faultless, brilliant, apart from a bit of overboost I`d forgotten how dynamic she is to drive.

However I noted today that when I am driving along (briskly) the oil pressure is just under 5 BUT when I accelerate hard it drops slightly and then builds back up. It drops to about 4.3 and then creeps back up with the revs??????????, go back to driving normally and it sits at just under 5 all the time.

Any idea why this might be happening? I`ve never noticed it before or is it normal for a 951 as I`ve never seen that before on any car I`ve owned?? Cant see any blue (turbo seal) smoke when I accelerate, and mates have told me she coughs a bit black but not blue when accelerating hard under full throttle, mind you she drinks the top limits of oil when thoroughly thrashed.

 

[PJS917]

Possibly the start of a faulty oil pressure sender, when my sender was failing as the engine was put under load the pressure dropped and built back up with the revs. Once I replaced the sender all was back to normal. The only ting is this was on my 968 not a turbo, so I would wait and see what the turbo guys say, if it is the sender it is only a £20. fix[][][]

 

[edh]

mine's doing something like this - dropping when accelerating & more marked on track with pressure showing 3 bar - I'm going to change the sensor this week sometime.

FWIW, there seems to be a different part no. for later models & is more expensive - IRO £40 from OPC Exeter

 

[Guest]

Mine drops when accelerating too...

 

[nick_968]

Mine too.....

 

[edh]

Top tips when doing this job on a turbo...

1. Read Clarks Garage first - yes the power steering pump really needs to come off its bracket to get good access
2. When they say short 24mm spanner, they do mean short...
3. It's much easier on an n/a 944

I'll see if there's any difference in the behaviour of the gauge tomorrow

 

[edh]

Well the new pressure sender does exactly the same - more marked when the oil is hot, dropping by about half a bar under load & then returning when you lift your foot.

So is this normal?

 

[edh]

I spoke to Jon M about this - his view is that it's likely to be electrical

either
a) engine earth strap - will test mine later
or
b) bad earthing in the instrument cluster - voltage changes in boost gauge affecting the oil pressure gauge. I know for sure that my instrument cluster wiring is a bit dodgy - I can move the needle on the boost gauge by flexing the steering column []