Just got an oil pressure gauge installed tonight. My Disco II is in the death vin range for the oil pump. Took the rover for a little drive. Everything appeared to be working fine, but I recall reading somewhere that pressure should be around 40 when traveling 55 MPH. Mine stayed more along the lines of low 40's.

After 5 miles, I stopped at a light and the low warning came on, but only on the pressure gauge, not the oil pressure light in the dash (so estimating 6-9 on pressure) Then when I go again, it comes back up. At every stop though it drops. Came home checked the oil, still full and no signs of leakage at all. So I assume this means I need a new oil pump? Starting to do research on this now but thought I would post as any info is greatly appreciated.

 

Well, you have a D2. The spec from the RAVE general data secton is 50 PSI at speed, and 10 at idle. The same 4.0 block and oil pump in a D1 is speced for 30-40 PSI at speed. I don't know why. The light does not go on until you drop below 7 PSI or as low as 3.5 PSI (switch is another electrical part made to brain dead engineer quality control standards - if the spec is 10 PSI minimum, why have a switch that goes off when you get 30 to 60% below spec???).
What do you have your low pressure alarm point set for, and what kind of reading are you getting at idle? What type and weight oil are you running? Please look at this posting: https://landroverforums.com/forum/di...estions-46975/. It shows a jumbo filter (there are a couple of Purolator numbers, read the whole thread) and shows readings with oils like Shell Rotella 15W40. Your type of oil and type of filter can have an impact. I did get a higher number at idle (low 20's, but not fully warmed up - only at 160F). Oops, forgot, that is another factor, how hot the engine is wher you are. Usually not a problem wih D2 engines....

Specs for D2

Low oil pressure switch opening pressure 0.24-0.41 bar (3.5-6.0 lbf.in2)

You may want to swap filter and repeat tests. Also, there is the question of the accuracy of your oil PSI sender. Don't know if you have something it could be tested against. And the kit of parts for oil pump is http://www.roverparts.com/Parts/8979K.cfm.

Another point - it certainly could be that low oil PSI is the result of worn lower end bearings. One owner detailed how he replaced his in-truck. See https://landroverforums.com/forum/di...earings-45707/ - but he was 20 PSI running....