Lost Oil pressure!

Hi, 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 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?
Jaguar XJ 40 -94 4.0 litre 6-cyl. 145000Km on the meter.
Pepe Jaguar XJ 40 -94 Soverign (Winter car) Jaguar XJS 6.0 -95 conv (Summer car)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Pepe, Probably everyone with an XJ40 has had the same problem with the oil sending unit. It is a common problem with these cars. Pick up a new one and it should cure the problem. Keep in mind that there are two different types. One that is like the original and sends bars up and down the scale and the other that is either on or off -- no gradients.
The caveat to all this is that you need to make sure that it is indeed a sender problem and not a pump problem. Seeing oil on the cams is a pretty good indication that it is a sender, but I would make haste to replace it.
Webserve

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thanks for your reply. I would like to check the pressure with a manometre. Do you know what tread there is on the sender unit? Is it 1/8" or 1/4" to fit to the block? Only when I can read the pressure on the manometre I can relay on the sender unit or the gauge. I hope there will be "good" pressure when I connect the manometre.
Pepe Jaguar XJ 40 -94 Soverign (Winter car) Jaguar XJS 6.0 -95 conv (Summer car)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.