The only
REAL Way to know what your Oil Pressure is from a Cold Start through to a Warmed Up Engine condition is to install a
TRUE Analog Oil Pressure Gauge with a LONG enough Hose to allow the Gauge Head to rest nearest the Windshield and be able to observe the Rise and-or Fall Off of Oil Pressure during your Test Drives.
The Nominal Range of Oil Pressure for the GMT360 4.2L LL8 Engine is 12 PSI at Idle near 600 RPM and 65 PSI at around 3,000 RPM
. An Excessively Dirty, Clogged Oil Filter can raise Oil Pressure at Idle and even allow the Gerotor Oil Pump By-Pass Valve to open wide and allow Un-Filtered Motor Oil to pass directly into the Oil Galleries.
After you Check Your Oil Level FIRST... "Follow The Bouncing Ball" of what follows to get this job done:
(1) Purchase THIS M16 X 1.5 to 1/4" NPT Oil Gallery Adapter Plug with Copper Sealing Washer:
(2) Purchase a DECENT Oil Pressure Gauge Kit with a LONG Hose that can reach from the Oil Filter Manifold up and over the Engine Block and allow the Gauge Head to rest adjacent the Windshield in Plain View:
(3) Remove the Hex (H-8) Plug from the Right Front Passenger Side of the Lower Engine Block:
(4) Install the Auto Meter Brass M16 X 1.5 to 1/4" Adapter...
Do NOT Over-Tighten this Item:
(5) Thread in the 1/4" NPT Male Hose End and snug it up TIGHTLY to a Leak-Proof condition:
(6) Run that Black Hose upwards and then snake it over the engine block and out from under the Rear Hood to a position where you can observe it while taking Test Drives:
(7) Observe the Gauge
BEFORE Starting the Engine:
(8) Observe the Analog Oil Pressure rise
( or fall off and become intermittent and unreliable) AFTER Starting the Engine
and compare what you see with the Dashboard OPG at the same time to know
precisely what the Engine Oil Pressure is on the Analog Gauge as the Motor Warms Up
...For The MOST Reliable Indications of Actual Oil Pressure:
(9) After these Test Drives(s) Reverse - Remove all of this Rig and carefully re-install the H-8 Oil Gallery Plug after touching up the Threads with a Non-Hardening Permatex Sealer. Then Re-Start the Engine and Check the area for any Oil Leaks.
(10) Large Fluctuations in Oil Pressure at any time; whether at idle or whenever observing Rising RPM, can indicate problems with a Worn, Torn or Failing Gerotor Oil Pump Rubber Grommet (Orange for later Model LL8 Motors ) or Blue Viton Rubber "O" Ring Type Seals on the 2002-2003 Model LL8 Motors in between the base of the Oil Pump Pick Up Tube and the Gerotor Oil Pump Manifold. A Clogged, Blocked Off and-or Occluded Oil Pick Up Tube Screen can be caused by an excessive build up of Gas-Gum Varnish and Carbon Build Up therein can also cause Oil Starvation and Air Cavitation at the Gerotor Oil Pump interface and create a catastrophic Oil Starvation condition .
Images Courtesy Amazon and @MAY03LT YouTube Video...