Land Rover Repair: oil leak from oil filter, time jody, misty spray

Question
Hello,
I have a 2000 TD5. It has an oil leak. It was leaking mildly for a while, then started increasing. then i put it in for  a service and to have the injector harness replaced (I was told by previous owner that it needed doing soon). That all went fine, but the oil leak increased and was actually quite bad. I took it back to the mechanic (they had cleaned down the engine at the service and said that perhaps just replacing the injecotr harness would fix the oil leak,but if not, at least the engine is clean so they can find the leak). At this stage there was actually enough oil coming out that there was a misty spray on the rear window. THey thought they fixed it. they said that the leak was coming out of the oil filter due to built up pressure because of a blockage in the breather system, so the pressure was blowing oil back through the filter. anyway, they replaced the oil filter and blew out the blockage. it seemed to have worked for a couple of weeks, but just this weekend i took it away on quite a long trip (5 hour drive) and noticed the smell of burning oil. when i lifted the bonnet to look, there was oil overflowing from the top of the oil filter (probably the top seal of the oil filter because it was drizzling down the filter itself). it isn't bad yet, but i suspect it will worsen again. do you have any ideas what could be happening?
THanks for your time,
Jody

Answer
Hi Jody,

interesting problem.  At first I thought blown headgasket and thus oil is being blown back.  Could it be as simple as a badly scored mating surface for the oil filter? How about a clogged pickup tube? I hope its not a cracked engine block.

From LR workshop manual:

Oil is drawn from the sump through a strainer and into the oil pump via the oil pick-up pipe. Pressurised oil from the pump passes through the oil cooler (if fitted) mounted in front of the radiator and returns to the full flow oil filter element. Oil from the filter passes into the main oil gallery and through internal drillings to
the crankshaft where it is directed to each main bearing and to the big-end bearings via numbers 1, 3 and 5 main bearings. An internal drilling in the cylinder block directs oil to the camshaft where it passes through further internal drillings to the hydraulic tappets, camshaft bearing journals and rocker shafts. Lubrication to the pistons, small ends and cylinder bores is by oil grooves machined in the connecting rods and by splash.

Lubrication:
Type Wet sump, pressure fed
Pump type Crankshaft driven eccentric rotor
Oil filter Disposable canister with full flow by-pass
Pressure at idle - minimum 0.7 bar (10 lbf.in 2 )
Pressure at 2000 rev/min (hot) 3.4 bar (50 lbf.in 2 )
Relief valve opening pressure 3.4 bar (50 lbf.in 2 )
Low oil pressure switch opening pressure 0.24-0.41 bar (3.5-6.0 lbf.in 2 )

Have the oil pressure checked, then remove the sump and check the tube, then pressure test the cylinders and then the coolant system to be sure you don't have hidden problems.

Just thought of something else, do you have high crankcase pressure?  If so, it could be crankcase vent relief valve/tube could be clogged.  It could damage the rear main seal and give you oil leaks galore.

Best of luck,

JohnMc