Low oil pressure and blue smoke from exhaust

All of a sudden my oil pressure (standard gauges) has gone from

7 at cold start
2 at hot idle
4 while cruising

To

4 at cold start
0 at hot idle (oil light also comes on dash)
2 while cruising

Also occasionally accompanied by blue smoke on the overrun?

I have drained and replaced the oil (10w 50 Fuchs)
Cleaned the oil pick up pipe
Checked hot compression (all 4 were between 125 - 135 psi)
Checked turbo play, was minimal movement and only a light coating of oil in the intake pipes

Any ideas on where next to check??

Oil pump mate ? Any history on it ?

What's the condition of your sump pan?
Has it been flattened at all? Even a slight nock can effect the oil pickup.

Have you had any work done on the car recently or anything changed?

Johnny, no history on the oil pump so must be old?

Stu, put another sump pan with no dents or knocks on it when I changed the oil but still got the same symptoms?

Aaron, only swapped the rocker cover over recently.

Did you clean the rocker cover? Or have it sandblasted and painted ?

A mate done this years ago and didn't clean it after it was blasted and painted and all the beads went round the engine and had the same issues as you mate

Sounds like oil pump unless you have any internal hemorage, are the camshaft spray bars tight? Any strange noises?
Did you change the oil filter?

oil pumps themselves are quite rare for problems, bypass valves can be an issues.
worn mains big ends etc leak more oil & thus reduce potential of oil pressure.
As thermal mentions, loose/broken/missing spray nozzles & chain spray gallery cap reduce oil pressures.
Highly likely going be stripping that engine to find problem & check/resolve damage done.
point on 5hit from rocker cover fitting is good one, blasting grit is superb at killing an engine.

Ring me today rocker cover could as said have been contaminated takes very little to do damage. It's under the rivited part that hides stuff. My oil pump parted after a lot of miles someone had it to bits tightened it up without lock tight on screws lots of miles later pressure dropped I check as much as possible few hundred mile later blown bottom end wish I had stripped engine soon as I noticed before it trashed it but you live and learn expensive and gutting tho to say the least. I certainly recomend a good mechanical oil pressure gauge to people. And I have adapters so you can run one and still keep the standard gauge so you don't loose stock look

Well phase 1 of the rebuild is now complete, dropped the engine and gearbox out of the car so will start the engine strip down at the weekend to see what's wrong?

Got a bad feeling it's going to be the main crank bearings that have gone though

We had a few issues when testing engines on the dyno at work, low oil pressure with worn main bearings, seemed to be related to over fuelling so diluting the oil and thus causing the wear, it would be worth checking it's all mapped OK regarding the fuelling when it's sorted. I always thought the big ends would knock first if there was any wear on any crank bearings but not always the case, but probably worth replacing big ends while it's all in bits.

Well fully stripped the engine down and found the following problems

2 of the shims had come loose from their rocker, one was sat in the head and the other had made it's way down to the bottom of the timing chain area by the oil pump.

Most of the crank and rod bearings were loose and worn in their seatings so there is my problem, JE pistons were all ok though.

Now got to get the crank checked over, the block bores checked and get rebuilding it again for the 4th time

Bob normally gives great advice on stuff like this so hopefully he sees post

Blimey, lots of loose bits then, good job you stripped it when you did, could of been really nasty it you kept driving it.

Mains appear to have picked up more so than bigends but does not look too bad tbh, maybe a good polish will get the marks out, but all guess work until it's checked out properly at engineers.

If you have previously honed cylinders you need to pay special attention to make sure piston to cylinder clearance is now not too large as every time it's honed that will pull a fair bit off cylinder walls and je pistons are noisy enough in a cold state as it is lol, so last thing you want is an overly sized bore to fit them in, in which case you may well be better off sourcing another block

Yes Bob, going to get the crank and block checked over at the engineers, got a spare block and head from the last rebuild I did so will use that if this one needs a rebore.

SORNED the car last night so I will do it all in slow time as a winter project now and also sort out the other little jobs that need doing ready for next years meets

Will keep you all updated with the progress

Good luck and keep us posted mate

Rebuild No4 in progress

Now to fit all the ancillaries and then get it back in the car and up and running

Some more pics of the rebuild.

Get in good man keep up the good work

Wow the fourth rebuild

Looking fresh mate

All looking shiney .... was it the main bearing that was worn ????

How to king bearings compare with Nissan bearings?