This is a Controversial Topic... and perhaps this is so because
So Few of US have ever completely Torn Down Any Used GM LL8 Motors and actually completely Cleaned This Crap off of EVERY Single Engine Surface... Right Down to Bare, Shiny Metal.
"Engine Builder Clean Freaks" ? Perhaps... But if so... I AM One of THEM:
ALL of these Engine Parts were once COMPLETELY Coated In Black Carbon MUNG:
These Images show the Before and After efforts of De-Glazing the GM 4.2L Engine Block of all Gas Gum Varnish and Carbon Build up on a 2004 Vintage Engine with around 160,000 Miles of Wear & Tear. I used (5) cans of ACDelco Top Engine Cleaner OUTDOORS with a Chemical Gas Mask, Nitrile Gloves...
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What also compounds this
'General Lack of Hands-On Experience' is NOT knowing
which Chemical Cleaners will Work Best
Without Destroying the Motor. I have worked though ALL of these issues, but before advising you to
"Go Ahead and DO THIS... And THEN ...Go Ahead and DO THAT..."
Please ...Consider
ALL of this Information Very Carefully:
(1) You should be Realistic with estimating just
How Much Longer you intend to Drive this SUV. If you take any Drastic Actions with attempts at performing
"Internal Cleaning" and the Motor suffers paradoxical problems as a result,
You Could Make Present Matters Even WORSE.
(2) Before taking ANY Actions whatsoever...
.YOU SHOULD INSTALL AN ANALOG OIL PRESSURE GAUGE AS DESCRIBED IN YOUR OTHER THREAD AND TAKE A BATTERY OF MEASUREMENTS FOR OIL PRESSURE OVER A WIDE RANGE OF OPERATING CONDITIONS.
(3) As I mentioned to you over in your other Parallel Thread on this Same Topic...
Nominal Oil Pressures for this GM 4.2L LL8 Engine are from 12 PSI at 600 RPM near Idle...and around 65 PSI at 3,000 RPM when the Gerotor Oil Pump can move over 11 Gallons of Oil Per Minute through this Motor.
(4) If the Oil Pressure(s) remain Nominal under these operating parameters and conditions...
Then DO NOTHING in the way of taking extravagant measures to 'Clean Up the Bottom End' of all this Black Mung Junk.
(5) If your Oil Pressure drops precipitously low and does so RANDOMLY... More than Likely...One of Two things (or BOTH) are happening:
(A)
The Oil Pick Up Tube has Clogged Up and has gotten so covered over with Black Mung Crap that the Gerotor Oil Pump is suffering from Oil Starvation. Oil Pressure? Nope... Then it becomes... Non-Existent!
(B)
Oil Starvation CAN create such a substantial Suction and Vacuum upon that Old, Tired, Flattened Out "Blue" Viton "O" Ring in between the Oil Pick Up Tube and the Base Inlet of the Gerotor Oil Pump... that it TOO Can Completely FAIL and become 'Open To Atmosphere' down inside of the Crank-Case. No Suction? NO OIL PRESSURE!
If either One or Both of THESE conditions have prevailed... then Removal of the Crank-Case - Oil Pan and probably removing the Front Timing Cover as well will become necessary too, as the Timing Chain Set is almost certainly in need of replacement on any such High Mileage Motor.
THIS WORK IS NEVER TRIVIAL TO DO!
(6) During any "Engine Tear Down"...Soaking the removed Oil Pick Up Tube in Berryman's Chem-Dip for up to Three Hours
would completely clean all of this junk out of the Piping and Off of the Screen Pick Up areas. And replacing the
"Blue" Viton "O" Ring will solve the problem of No Suction in between the Gerotor Oil Pump Lower Manifold and the OPT Mounting Flange.
(7) If your Motor is of a Later Vintage, then using the 2nd Generation
"Orange" Silicone Rubber-impregnated Flange Gasket would need to be replaced instead of the "Blue" "O" Ring Style Seal. You must NOT Mix-N-Match these two Sealing Methods in between the Early and late Model Engine Front Timing Cover-Gerotor Oil Pump Combos...
EVER.
(8) So...... In the Fewest Words Possible...
"IF IT WORKS.... DON'T FIX IT!"