Oil pressure sender unit?

Hi you english guys! Today when I took my car for going home there was no Oil pressure when I started. The pressure was just fine in the morning. Fine for me is on the middle of the scale. I think it means 4 bars or that what it reads, when OK.

But this evening the pressure was slowly raising to just

1 bars, just enough to let the lamp go off. I stopped and checked the oil level with the dipstick and the level was OK, just 1 or 2 mm below the "normall" marking. After a second start the oil pressure was still that low but when i opend the oil filler cap on top of the engine I could clearly see that the oil is flooding the cam shafts. It seams that there is pressure and there is no noise from any bearings or valvetrain. A thing I notised is that it takes about 5 seconds for the oil pressure to drop from 1 bars to 0 bars.

Is there a problem with the Oil pressure sender unit? Has anyone out there had the same problem? What size is it on the thread for the sender unit? I would like to check the pressure with a manometre. What tool is recommended for removing the sender unit? I can see, there is not too much space in there...

Jaguar XJ 40 -94 4.0 litre 6-cyl. 145000Km on the meter.

Pepe in Sweden Jaguar XJ 40 -94 Soverign (Winter car) Jaguar XJS 6.0 -95 conv (Summer car)

Reply to
Pepe
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Electrically operated oil pressure gauges are notorious for giving wrong readings. First thing to do is remove the connectors from the sender, clean and replace making sure they are a tight fit.

The sender is removed with a spanner of the correct size - sorry not to be more helpful, but they're not normally difficult or tight. It's certainly a good idea to check with a known good gauge anyway.

Reply to
Dave Plowman (News)

I once had this problem with a Hillman Imp. The pressure read low, and got lower as the engine warmed up. A close look at the unit showed that there was a small seepage of oil near the electrical connection. A new sender unit made a lot of difference.

Not sure, but it is a common size - try 7/16 AF or 12mm and see if you need to go bigger or smaller. The unit normally has a slight taper on the thread, so once you have started it moving, it comes out easily by hand.

Have a close look at it too. It is OK to be dusty but it should not be oily.

The other possibility, though less likely, is a wrong reading from a good sender because the gauge has a problem. I don't know Jaguar electrics, but many British cars provided power to the gauges through a voltage regulator. If the regulator is faulty, then the gauges will not read accurately. Have a look at the fuel gauge. Is that reading low as well as the oil pressure gauge?

Jim

Reply to
Jim Warren

"Jim Warren" skrev i meddelandet news:63yud.34783$ snipped-for-privacy@text.news.blueyonder.co.uk...

Thanks guys for good advices.

I have to get under the car and see what I can find out.

I don't think there is a problem with the electrics.

The tank level and water temp has a normal acting.

I hope I can find a nipple for the manometer and see

if I can read the pressure before taking next action.

Thanks again

Pepe

Reply to
Pepe

Yes, but if it's an electrical sensor, could be a poor connection to it. Which wouldn't effect other gauges.

Reply to
Dave Plowman (News)

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