Oil Pressure Tests
Correction on first post - Idle in *DRIVE* - waiting at the stop light, after coming off the highway - oil light flickers - when oil good and hot, and nearing time for oil change.
The Oil Light flickers - sometimes, under these conditions - for several years now.
Anyway - so I have a ticking valve, or rocker, in the front bank, confirmed by listening carefully,
and by pulling off the front valve cover to have a look.
Nothing broken, in front bank valves, but all rockers have a little play, but I have read this may be normal.
[ Some manuals indicate something like a 2 to 4 mm gap between valve stem and rocker end - is spec'd when engine is off, and
when hydraulic roller lifters are not pumped up / bled down / no oil pressure / when engine is not running.
So I figure a little rocker looseness on engine stop - is normal. Not totally sure. But that is what I noticed.
This play is taken up, in theory, when the engine runs with oil pressure, and the lifters pump up - to zero valve lash.
All 6 rockers on the front bank - do indeed have a little "play". ]
I figure I have one or two roller hydraulic lifters, stuck, or not totally pumping up, or maybe one or two of
the valves worn more, due to high mileage, ie. stem, rocker, pushrod - or something in the mechanism worn a little more than the others - so ticking.
And this ticking valve has been going on for awhile now - couple years, and not too serious yet. Otherwise engine runs well enough.
Given the car has near 275,000 km - I may have a few contributing issues.
But given the flickering oil light, sometimes - I decided to start to investigate my Oil Pressure.
Since Proper Oil pressure is needed to operate / pump up the hydraulic roller lifters - and proper Oil Pressure is important
generally for your engine to operate well.
So I start with Oil Pressure tests.
I Get a good Mechanical Pressure Gauge - and improvise an oil pressure gauge.
[ Lee Instruments, 0-100 PSI
gauge, for around $20 at Princess Auto, and with a few brass fittings, nipples and
a short piece of good rubber hose, screw clamps - and improvise a gauge. ]
I remove the oil pressure sender, top of block, driver side, behind thermostat housing, and thread in my tester / improvised gauge.
I get to it more easily, by removing the black plastic air cleaner box, after the air filter and before the intake.
Install the mechanical gauge, put the air cleaner box back.
Start warming up the engine and I take readings.
A mirror strapped on the driver's side headrest and a light to light it up better, help me look at the reflection of the Tach on the dash,
to see RPM
s. Tilting down the steering wheel, helps the mirror see through the big opening in the steering wheel, to see the Tach in the mirror,
from the driver's side of the front engine bay - where I am working.
ie. I'm working in the engine bay, looking at the pressure gauge, and looking through the windshield at the Tachometer on the dash
through a medium sized mirror, maybe 10 x 14 " square mirror, I have strapped up on the driver's seat headrest. A light helps see the tach better.
I am able to rev up the engine from the engine bay, because I have discovered that under the black plastic throttle cover on top of the engine,
if you put your fingers in the gap on the side, you find a metal tab, and if you push it, you rotate and activate the throttle - reving up the engine.
To make a long story short - YES - I definitely have lower than normal oil pressure - mostly when the oil is very hot.
Spec for this engine says you should have between 40 - 60 PSI
oil pressure at 2500 rpm
And there is a BIG BIG difference in readings - between cold oil and hot oil.
IMPORTANT - you must get the oil and engine GOOD AND HOT - to get meaningful readings.
Cold oil - I have 40 PSI
at Idle ! 600 rpm
- dropping down slowly as the engine and oil warm up.
But imagine this ... after a warm up and a 15 minute highway run, oil good and HOT now ...
HOT OIL and HOT ENGINE. dropping down to TWO (2) PSI
at idle 600 rpm
and only Thirty (30) PSI
- at 2500 rpm
So this is significantly below spec. Should be at least 40 PSI
- when hot.
at 2500 rpm
HOT. Not enough. Definitely low.
at 600 rpm
idle HOT ! this is surely too low, and is why the oil light flickers under this condition.
Not killing the engine - but I think I have some issue.
Maybe a weak / worn oil pump (not surprising, given mileage of car)/ or some obstructions / restrictions.
So low oil pressure is confirmed - when hot.
Reading more and researching the subject online - indicates lots of people have sludged up / plugged up Oil Pump intake screens - at the bottom of the oil pan.
I decided to try and check that out first.
I would not be surprised - given the age of the car - if there is some sludge - bottom of oil pan - and plugging up bottom of pump intake screen.
Oil changes always done on time - by me - always had good oil, so figure oil pump probably not that bad.
And read that the oil pumps are pretty bullet-proof in these cars. So I figure oil pump may be ok.
But I did a sludge out treatment before last oil change - 4-5 months ago.
So I figure some sludge may have migrated near the bottom of the oil pan.
And I see many pictures online of sludged up intake oil pump screen.
I'm investigate this next - since I can do this myself.
Let's see if I may have sludged up / restricted oil pump intake screen.
posts will follow.