Atlas 4.2L LL8 Timing-Bare-Bones-Bulletproof-Cyclopedic-Set&Reset

[808]

!!!!Salutations Wrenching Family!!!!

In my recent days of extreme review,
it has been my pleasure to quest for:
mechanical grasp of this timing system.

The data set is exceedingly vast, and the methodology is surgically acute.

It is my desire here to synthesize & exact a list of -panoramic steps-.

The scrupulous invulnerability of this meticulous approach is given in full view of the drastic profundity of this procedure.


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1/11/2023: 4.2L LL8 Timing: Rigorous Mechanical Practicum Methodology Update
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-A.- ACCESS ZONE:
INITIAL STEPS

1. *Complete All RATIOCINATIVE steps in pre-cleaning outer Engine Case & removal of Camshaft Cover.*
(If -In Vehicle-, All Accessories, Radiator, A/C Condenser, Hood and Front End Removal *Should* Be Anticipated)

2. Remove all spark plugs.

3. Approximate engine clockwise, observing Cyl. #4 for TDC approach & zenith: 1-5-3-6-2-4 = #1 TDC = NEXT.

4. Observe Cyl. #1 approaching TDC, install TDC indicator to Cyl.#1, install Dial Gauge above TDC indicator.

5. Continue rotation towards zenith @ circa 23 mm of *TOTAL* TDC plunger travel expression.

6. Begin scribe index of orientation relationship degree marks with harmonic balancer pulley outer lip & front cover.

7. Confirm, note TDC zenith degree, record mm @ calipers, rotate past this point until TDC plunger fully retracts.

8. Remove the dial gauge & TDC indicator, complete 13&1/2 rotations of the engine, reinstall TDC indicator&dial gauge.

9. Observe absolute zenith @ cylinder #1 TDC, remove dial gauge.

10. *If In-Vehicle* : place J44226-3 @ oil pan access hole to flex plate bolt.

11. *If On-Stand* : restrain flywheel orientation braced opposing *counterclockwise* rotation.

12. Mark relationships of camshaft sprockets to chain.

13. Complete the counterclockwise removal of the harmonic balancer bolt.
***THIS BOLT MOST LIKELY WILL REQUIRE A SERIES OF 4LB SLEDGE HAMMER SHOCKS WITH A BLIND PUNCH***
***THIS 24MM FITTING WILL REQUIRE DEAD LOAD PATIENCE, AND POTENTIALLY 4 FT. OF ADDED LEVERAGE ON A 3/4" RATCHET***
***IF ON STAND, THE ENGINE BRACKET REQUIRES FALSEWORK RESTRAINT BRACE AGAINST THE SLAB***

***AT EVERY *CRACK* OF THIS TTY FASTENER, HAULT THE LEVERAGE LOAD & ***
***DELIVER FURTHER *DIRECT* SHOCKS AT THE CENTER OF HEAD OF THE FASTENER***

14. Complete the removal of the harmonic balancer pulley & front cover oil seal.

15. Mark Oil Pump Gear Orientation.


-FOR COMPLETE ACCESS TO THE TIMING SYSTEM, THE OIL PAN *MUST* BE REMOVED-


16. *If On-Stand* : Invert the engine orientation for ease of removal.
16. *If In-Vehicle*: remove the J44226-3, break all oil pan bolts loose, back off fasteners halfway or less.

17. Gently tap the oil cover if necessary to aid in breaking the RTV bead, use caution not to pry excessively.

18. Use jackscrew locations provided to begin separating the pan from the block, allowing for the fasteners to "catch the pan".

19. Template Fasteners, Remove the oil pan, shim pan if necessary - no heavy leverage angle/eccentric force to pan edges.
(RECOMMENDED PURCHASE OF NEW OIL PAN FOR EXPEDIENCY)



******************UNBOLT THE OIL PUMP PICKUP TUBE **********************************
********FROM THE CRANKSHAFT CRADLE/OIL PUMP RELATIONSHIP*********************
(RECOMMENDED PURCHASE OF MELLING PICKUP TUBE)

********************DO NOT SCORE THE PICKUP TUBE DECK********************************

*If In-Vehicle* : Replace J44226-3 @ flex plate bolt& or 15mm to starter port&shim accordingly.

*If On-Stand* : restrain flywheel orientation braced opposing *counterclockwise* rotation.

-Reset Engine In Plan View Orientation-
-MARK FRONT COVER RELATIONSHIP TO BLOCK-
20. Removing front cover center bolt first, template remaining fasteners and note condition. All reused threads require cleaning.
(RECOMMENDED PURCHASE OF *NEW FRONT COVER BOLTS/INNER SPACER BOLT* & *NEW FRONT COVER* FOR EXPEDIENCY)

21. Using jackscrew locations, introduce cover fasteners, allow time between jackscrew turns, -gently- pry case @ given overlaps.

22. Remove the cover forwards without tilt, crankshaft sprocket mandates straight line forward removal.



COMPLETE TIMING SYSTEM ACCESS HAS BEEN ACHIEVED.

 

[808]

B: BAREBONES BULLETPROOF

-REMOVAL-
-VVT CMP FINAL ORIENTATION-
-RESETTING CAMSHAFT TIMING-
-CHAIN ORIENTATION/TENSION-
#1: FIRST ORDER
-REMOVAL-

1. Assess presentation of: camshaft flats, sprocket relationships to dark chain links, chain tensioner, and guides.

2. Clean Face&Side of VVT CMP Actuator, mark reluctor ring relationship to sprocket hub, check for initial play.
(IF THE VVT ACTUATOR IS FOUND TO BE UNLOCKED, THE POSSIBILITY OF IT'S FATIGUE FAILURE MODE IS HIGH)
(FOLLOW SI DIAGNOSTICS TO ASCERTAIN THE LOCKING FORWARD ADVANCE ABILITY IF REUSE IS DESIRED)

****AUTHOR'S NOTE: THE REPLACEMENT OF THE VVT ACTUATOR IS STRONGLY RECOMMENDED****

3. Mark/note/define all sprocket to chain relationships desired.


****AUTHOR'S NOTE: THE REPLACEMENT OF ALL TIMING COMPONENTS SHOULD BE CONDUCTED AS A WHOLE****

(THIS INCLUDES ALL SPROCKET BOLTS - PREVIOUS TTY FASTENERS HAVE REACHED THEIR ***YIELD ZONE*** UPON INSTALL)

(ALL BOLTS DIRECTLY RELATIVE TO THE SHOE, GUIDE, TENSIONER, RECOMMENDED NEWLY PURCHASED)


4. Install the J44221 to the camshaft flats if possible. If not possible, clamp restrain the camshafts against sudden rotation.
(This is a safety factor for the technician & the valve seats-the valve train springs are in stored tension)

-->Theory Note: At this point, *localized restraint* has been executed to the camshaft flats.

The J44221 is not a flatness verification *timing tool*.
The J44221 is a camshaft flat *holder*.
The J44221 cannot verify camshaft flats at flatness.
The J44221 is a redundancy restraint.

-->Theory Note: At this point, the crankshaft main pin/sprocket should be at 12:00 high.

The relationship of engine timing is defined by the exacting position of cylinder #1 at TDC.
The hierarchical consideration of the engine position is defined by the crank orientation.
There is no additional authority on the relationship of the timing of the engine.
The crankshaft, at 12:00 high, requires capitulation of camshaft flatness.
The crankshaft pin rules the the entirety of the final timing orientation.
The crankshaft describes the relationship of camshaft flats.

5. Collapse The Timing Chain Tensioner by manipulating the lock lever counter clockwise if possible.
(The Tensioner Pawl May Be Locked Hydraulically Extended By Dirty Internal Oil Compaction)

6. Assess the condition of the Tensioner Bolts.
(These Bolts May Require Heavy Blind Punching & Shocking)
*EXTREME CARE MUST BE TAKEN NOT TO DAMAGE THE TENSIONER DECK*

7. Remove The Timing Chain Tensioner.

-->Theory Note: At this point, The Crankshaft Sprocket to The Exhaust VVT Sprocket tension has been "removed".

The 3 potential points of pending "vulnerability" at this immediate point in removal are:

a.Plausible "Damage" To The Exhaust VVT - If restraint at the camshaft hex is not maintained.
b.Stored Tension At The Intake Camshaft
c.Gouging The Camshaft Snouts

8. Remove The Exhaust VVT Sprocket Bolt in restraint, remove the Sprocket.

9. Remove The Crankshaft Sprocket.

10. Remove The Intake Sprocket Bolt in restraint, remove the Sprocket and chain.

11.*DISCARD ORIGINAL TTY BOLTS FROM EXHAUST & INTAKE CAMSHAFT SPROCKETS*.

12. Remove Timing Guides & Shoes, Note Characteristics, Relationships, Orientation. Deposit Bolts in Template.

-->Theory Note: At this point, the only stored tension in this system should be held in the Valve Train Springs.

-->Theory Note: Protocols Stated Accordant To The Observance Of All PIP's & TSB Relative To Developmental Concern

 

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#2: SECOND ORDER
-VVT CMP FINAL ORIENTATION-
-->OPERATION NOTE: From this point, configuration proceeds with added checksum opportunites in redundancy
1. Assess the condition of the New CMP VVT Actuator Sprocket. Surface area detail solvent cleaning may be necessary.
(If desired, perform SI Diagnostic Bench Testing before final install - Unlocked Max Travel Range Spec: 14-15mm.)

2. Ensure CMP VVT is in a *FULLY ADVANCED* POSITION prior to installation.
(Redundancy Check Calibration Opportunities Follow - There should be 0% play @ "Fully Advanced ZERO°)

3. Mark The Relationship Of The New CMP Reluctor Face to the Sprocket Hub to denote 0° orientation.

3. Assess the condition of the New Timing System Components. Ensure all members are in dust/particulate free status.
(Verify That The Timing Chain Tensioner Is Without Error/Surface Damage To It's Block Flatness Mounting Agreement)

4. All block ports for components picked/solvent cleaned/vacuumed or blasted with *dessicant* shop-dry air supply.
(THIS EXCLUDES THE SPROCKET TTY BOLT PORTS - WHICH CARRY OIL AND MUST REMAIN DUST FREE)

5. Install The Timing Chain Tensioner, leave retracted(do not pull the pin yet).

6. Install The Timing Shoe and The Timing Guide.

7. These components need to be verified in their mating surface relationship orientations before proceeding.

8. Torque these components to spec. Mark/Record Bolts Torqued.

9. Introduce The Exhaust VVT Actuator factory timing line into the center of a *New* Timing Chain mark dark link.

10. With the chain draped over the Exhaust Sprocket, feed the chain down into the block, route the chain over the
crankshaft snout without side loading bend or stress to the chain.

11. Using a *NEW* Exhaust Camshaft TTY bolt, Introduce the CMP sprocket pin to the exhaust camshaft snout race,
taking care not to score the snout surface.

- Hand Tighten The Bolt. -

11. Apply a finger skim coating of fresh motor oil to the interior surface of The Crank Sprocket. Install onto the Crank Snout.

12. Verify the chain *IS* traveling centered in the black plastic shoe.

13. Mate a dark timing chain link with the crankshaft sprocket factory line from the CMP draped orientation.

+Verify The Chain Is Centered & Routed On The Plastic Shoe & Guide-NOT THE SHOULDER LIPS+
+This Is Imperative For Routing Geometry.+

13. Draw the slack chain up and through the center of the intake guide plastic, and mock hang the chain in place on the top of the camshaft cover lip using a plastic handle screw driver or rigid plastic shaft.
+Verify The Chain Dark Links Are Mated @ Crankshaft & CMP Factory Marks.

-->OPERATION NOTE PROVISO: THE STORED TENSION IN THE INTAKE CAMSHAFT SPRINGS IS PRESENTLY ANTICIPATED.
HERE ADOPTS COMBATIVE PROTOCOL FROM TSB 07-06-01-018A@Engine Cylinder Head Installation STEP 15:
&"This may require removal and reinstallation of one or both camshaft sprockets"&

The Exhaust VVT Sprocket -in this order of installation- should not have required any camshaft rotation.

The Intake Sprocket - in this order of installation - with all timing marks correctly associated,
*SHOULD* require intake camshaft rotation.

*FRESH* Chain Length w/fresh component dimensions *SHOULD* require reorientation of the cams.

The impending J44221 removal does not constitute an emergent concern.

The technician needs to be aware that:
only camshaft hex manipulation provides sudden spring release of cam lobe base circle rotation.

The technician can "rest easy" with the essential movement of the camshafts during this phase.

14. Remove the camshafts from clamping restraint/remove the J44221.

15. Locate a 1" box wrench to the intake camshaft hex.

 

[808]

#3: THIRD ORDER
-RESETTING CAMSHAFT TIMING-
-->OPERATION NOTE: At this point, primary set & laggard camshaft timing requiring reset is adressed.


There is no additional procedure for setting this fundamental camshaft flat relationship.

With the restrained crankshaft ring gear holding the engine at TDC,
camshaft flats are now mandated to be described in flatness @ .005/0.13mm
ENGINE AT TDC MANDATES = CAMSHAFT FLATS LOCATED @ .005 / 0.13mm

The camshaft flats, at this point, should be orientated as close as possible to flatness.
____________________________________________________________________________________________________________
This is not the only opportunity to achieve flatness in this procedure.
____________________________________________________________________________________________________________
Full regard need be given to any notable movement of counterclockwise exhaust
camshaft rotation, as this may constitute slackening/unlocking/retardation of the CMP.
____________________________________________________________________________________________________________
This is not the last opportunity for a fully advanced VVT CMP in this procedure.
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Adjusting Camshaft Timing:

1. Both Camshaft hexes may be simultaneously manipulated if desired by the technician.
2. Using a flat edge in testing, manipulate the exhaust camshaft to advance towards flatness first, if possible.
3. Using a flat edge, holding mindful wrench restraint, manipulate the intake camshaft to flatness agreement.
4. Verify "primary final" check @ flatness agreement(This is Best Case)

5. Use elevated tables if possible, place the intake sprocket and bolt within reach.
(IF THE TECHNICIAN HAS UNCERTAINTY SURROUNDING ORIENTATIONS OF THE CAMSHAFTS-
(MARK RELATIONSHIP OF THE CLOSEST POINT OF THE CAMSHAFT ENDO TO BEARING/CAMSHAFT PILLAR CAP
(WITH A FELT TIP PEN) - (This is also erroneous, but may be used to measure agreement frequency if desired)

6. Introduce the Intake Camshaft Sprocket Factory Line into the corresponding dark chain link at the chain mock up.

+Visual Check Verify That All Sprocket Factory Lines Agree With Dark Chain Links Before Proceeding+

7. Hold the Intake Sprocket in position with the left hand, taking care not to score the intake camshaft snout,
manipulate The Intake Camshaft into position with the right hand, adjusting the intake camshaft accordingly.
The degree of manipulation to introduce the Intake Sprocket Pin to the Intake Camshaft Snout should not be excessive.

+IF DIFFICULTY IS DUE TO A CLEARANCE CONFLICT INDICATION -> RE-VERIFY GEOMETRY+
+THE VALVE TRAIN SEATS MUST BE PROTECTED FROM SUDDEN INTERFERENCE+
+HALT THE PROCEDURE, EXAMINE ALL PORTS, QUESTION ALL CRITICAL PATH STEPS IF INDICATED+
+WAS THE STATUS OF THE VALVE TRAIN VERIFIED AND INSPECTED, ETC.+

8. Using the *FRESH* Intake TTY Fastener positioned nearby, secure The Intake Sprocket to the Intake Camshaft Snout.

- Hand Tighten The Bolt -

9.14. Return the camshafts to clamping restraint/replace the J44221

****AUTHOR'S NOTE:

At This Juncture, The "Hair Raising" Events Have Truly Culminated.
This only by provision that all lines of effective consideration have been addressed.

Here follow the "Bulletproof" Steps that give any technician as many "chances" to finalize these orientations as needed.

From this point in the protocol,
there follow an innumerable quantity of available "opportunities" to complete finalized orientation of this system.


***PROVIDED***:


The Technician *IS* willing to complete further rotations of the engine.


In departure from factory service normalcy,
and all scenarios proceeding to immediate
torque to torque angle geometry.

IN FULL VIEW OF: 1st Clamp : Intake Sprocket Primary Torque @15 lbf-ft First Pass
100° T.A. Final Pass

2nd Clamp: VVT CMP Sprocket Torque @18 lbf-ft First Pass
135°T.A. Final Pass

This application of exacted structural theory is as follows:


TTY BOLTS MAY BE FREELY ADJUSTED
***BEFORE REACHING THEIR YIELD ZONE***

++++++Primary bolting could be conducted If a target zone safety factor of 30% at minimum is retained++++++++
This provides the opportunity to torque an exact clamping force:
Sufficient To Subsequent Observation Sequencing.

Adopting a 50% safety factor (*TO TORQUE, NOT TORQUE ANGLE*)(Safe x Safety)
7.5 lbf-ft (*This Be Conservative By An Order Of Magnitude^s*)
9 lbf-ft
Adopting a 40% safety factor,
9 lbf-ft
11 lbf-ft
At these minimal values of *extreme over compensation* for the application of these fresh bolts,
Any Number Of Adjustments May Be Made

*WITHIN THIS ZONE OF REPEATABILITY*

At no point would these bolts approach stretch.



***PROVIDED***: The practitioner is in agreement with these figures of presentation,


#4: FOURTH ORDER
-CHAIN ORIENTATION/TENSION-

1. Holding The Intake Camshaft Hex, tighten The Intake Sprocket to 9 lbf-ft.

2. Holding The Exhaust Camshaft Hex, tighten The Exhaust VVT CMP to 11 lbf-ft.

3. Reintroduce the Antiquated Harmonic Balancer Bolt to The Crankshaft Snout and snug gently.

+Remove The Tensioner Locking Pin+

4. Remove the camshafts from clamping restraint/remove the J44221.

5. *If In-Vehicle* : Remove J44226-3 @ flex plate bolt & or starter port.

*If On-Stand* : Unlock flywheel restraint.

6. Complete 13 clockwise engine rotations and prepare to locate TDC with the TDC Indicator Tool &Calipers & Dial Gauge.

7. Achieve TDC Zenith again following another rotation @ recorded mm expression of TDC plunger / Dial Gauge

If unsatisfied with accuracy of reading, or uncertain, repeat rotations w/adopted degrees to crank bolt orientation sweep.

8. Verify:
= All Timing Chain Dark Links In Relationship With Camshaft & Crank Sprocket Lines to *OEM CHAIN DIAGRAM*

= Cam Flatness Sustained Condition @ .005/0.13mm

= CMP FULL ADVANCE SUSTAIN ORIENTATION - CLOCKWISE CAMSHAFT ROTATION "SHOULD LOCK" THE CMP @ 0°

= Appropriate Timing Chain Tension To Intake Sprocket VS Crank Sprocket & VS CMP Sprocket.

This Redundantly addresses:

A. Inappropriate chain installation concerned with misconfigured cogs.

B. Insufficient flatness at Cam Flats that:

*MAY* be directly relative to fine orientation of the camshaft to sprocket ^^^^clamping relationships^^^^

C. A CMP That may have been inadvertently retarded during manipulation or installation:

COUNTERCLOCKWISE ROTATION OF THE TIMING CHAIN OR EXHAUST CAMSHAFT CAUSES THE VVT CMP TO RETARD

D. Any Timing Chain SLACK OR SLOP that indicates a serious configuration issue is apparent.


______________________________________________________________________________________________________________
REFERENCE TSB 07-06-01-018A@Engine Cylinder Head Installation STEP 4:

Notice: Tension must be always kept on the intake side of the timing chain to properly keep the engine in time. If the chain is loose the timing will be off, which may cause internal engine damage or set DTC P0017.

REFERENCE 2008 4.2L Engine Mechanical:

Fig. 149: Rotating Engine Clockwise

Courtesy of GENERAL MOTORS CORP.
23. Rotate the engine clockwise by hand two complete revolutions to TDC number 1 on the compression stroke. Refer to First Method or Second Method for TDC. If you go past TDC, rotate the engine back approximately 45 degrees before TDC and then rotate clockwise up to TDC to ensure that the timing chain is tight (no slack) between the crank sprocket and the timing gears.
_______________________________________________________________________________________________________________

^^^As stated, and well noted most specifically - (NO SLACK) - need be "defined" in it's nature of relativity to the chain to sprocket relationship. These rotations will provide exactly that, giving the repetitive opportunity to monitor & adjust for the ***exacting*** of the desired chain tension^^^


****AUTHOR'S NOTE:

In This Bench Test configuration, any exhaustive number of modifications, adjustments and reorientations could be conducted "endlessly" within the clamping values prescribed above. - & - Manual Oiling

Fine adjustments and demonstration of the camshaft flatness uniformity can be conducted at length.

Adjusting the Timing Chain Tension, the Tensioner pawl could be gently retracted a number of instances if desired, however, I would encourage a modicum of restraint to that opportunity. (Only hydraulic actuation demonstrates it's comprehensive actuation) -

***Each uninstall/install of this mechanism provides the potential for particulate introduction to the Tensioner Deck*****

Sweeping this mechanism back and forth on the fulcrum of it's fasteners could score the face of the block deck - %By The Tensioner itself%
The particulate potentially created from disturbing the fastener thread schedule mating relationship may become trapped between the deck surfaces.

This specific relationship is iron ore vs aluminum.
The Tensioner Deck surface "Flatness" *COULD* infringe on the block deck mating surface.
-Verify All Deck Mating Surfaces Before Mating-

14 Full Rotations give the fullest opportunity of review intervals to monitor all of these performance variables.

The only necessity of application for "pausing" this ongoing bench testing
for fundamental sprocket or chain removal
would be reintroducing restraint at the crankshaft.

The additional added benefit for the mechanic without the opportunity for use the J-44226-3 (or the desire) is depicted in the heightened ability to apply ring gear restraint in *direct opposition* to the specific force of rotation required for final torque down procedures @ camshaft sprockets in clockwise torque angle.

Halting the procedure may occur when the number of bench test rotations has sufficed to demonstrate:

BULLETPROOF.

May These Contingencies Assist Expansive Potential.

Best Regards,
808