re : 1987 LAND ROVER LR 90 DEFENDER

When driving the oil pressure is ok but on idle its about 5 to 10 on the gauge - the bottom end sounds ok ? Is this a major cause for concern ?

Many thanks
NB.

 

The drop in oil pressure at idle is typically due to increased rod and main bearing clearance.
Extra clearance due to wear in the oil pump housing will also create this situation.

At higher engine speeds the pump moves enough oil to maintain pressure dispite the wear.

The engine may operate like this for extended periods.

Replacing the pump may postpone the needed rebuild.

 

You need to do a mechanical oil pressure test to verify the real pressure numbers, then you might consider doing a good engine flush to see it it will improve, if that doesn't help, pull the oil pan, clean and inspect, especially the oil pick up tube that are known to plug up.
Mike