Hello everybody,
So I'm not sure here, is the digital oil gauge for the digital dashes an oil level or pressure? Mine shows 8 most of the time, wanting to know if this is normal?

 

Pressure. I haven't the digital in mine. I do believe 89-91 gauges were accurate and changed with pressure, after that they just went to high noon and didn't change with a pressure change.

 

Hi,
the digital gauges went up to vin594575. They changed back to conventional style gauges from vin594576 to vin629285 and changed again from the '91 on, vin629286 to the end of the XJ40.
My vin is 629388 and my gauge varies from about 5 at idle, slightly higher around town and about 6 at high rpm and faster motorway driving. The gauge is in x100kpa. My 4.0 Jaguar/Daimler handbook is worded to say that the gauge does vary depending on pressure and it is to not drop below 275kpa.
BTW my gauage's maximum is 8.
You may find that your oil pressure sender is faulty.
To test it remove the wire from the sender with the engine running and the gauge should go to zero. Touch the wire from the sender to the engine or somewhere else to get a good earth to the wire and it should go to the guages maximum (8 on mine). If you get both results that I just mentioned than it is the sender. If you get no change and it stays on maximum (if 8 is maximum on yours) than you have a short somewhere between the sender and the gauge.
Never connect a live positive wire to the sender side of the pressure gauge as it will probably blow you gauge. The sender side works of earth.
The oil pressure sender that doesn't change the gauge reading is one that is either on or off depending on the pressure. A gauge needs one that has a variable resister that allows a different voltage flow through it depending on the oil pressure, this varying flow is what changes the gauges reading.
Up to vin594575 the senders part number is DBC4418. From vin594576 to engine number 103370 the part number is DBC5513. From engine number 103370 on the part number is DAC7879.
An optional part with number LMD5640AB was introduced to stop the oil pressure gauge from "fluctuating", this one is the one that just reads an unchanging pressure unless you get low pressure then it drops to zero, on/off only.

Picture on the left is LMD5640AB. Picture on the right is DBC4418, all the senders that vary the gauge reading look basically the same.

Hope this helps, and to anyone else that wonders why there gauge never changes. It's the sender not the gauge.

Valguard.

 

Thanks so much, very helpful post indeed