808's 4.2L LL8 TOME

808

Original poster
Member
May 5, 2022
209
Georgia
Gentlemen!!!

As Sir MRRSM has so aptly stated previously, now begins a "TOME."
(I had thought of entitling this "4.2L LL8 Comprehensive "TTY-FREE" Valve Train Day Spa R&R Becomes "TTY-INEXORABLE")

Herein Begins:

"The Tale Of 808's Road Dog"

I took ownership of this 2008 Chevrolet Trailblazer LT rig circa 27K miles in 2010. What began in 2015/6 with an Exhaust Manifold crack at the vane radius to collector directly associated with Cylinder #3 had been approaching and now has finally reached the pinnacle of it's existence as a *sustained* mechanical condition that will forever code without a valve job intervention.

Dr. Borescope Said: "Crispy. Tribological Brutality. Fatiguey No Seatey."

Tribology Series 27, Dissipative Processes In Tribology: Page #445 begins here.


Oddly enough, this specific anomaly occurred in 2015/6 after I performed a -((regarded appropriately in hindsight now that I'm aware of the *ABSOLUTE* Necessity of the AC-Delco 41-103 Gospel))- *HEATHEN* tune up with NGK plugs after being steered into wayward waters by some well meaning creature employed at Auto Zone. Immediately following the completion of this "update" of the plugs, I ^even now^ recall the marked sound of the exhaust manifold rupturing/cracking at turnover.

+
Before I go further, I pose the question to the community: "HOW could those NGK iridium plugs have caused that?"

This occurred on a hot Texas summer day.

Precedent weak fatigue space in the casting exploited by random calamity from the Godless NGK Idolatry??? lol

It would seem plausible that a misfire on that specific cylinder would possibly present an issue, but cracking an exhaust manifold?

The consideration of "coincidence" as a plausible explanation fetches unlikely for my review considering acute *condition change*.
+

During that period of time, I had a "WELD EVERYTHING" approach, which yielded a number of solid developments, but this, unfortunately, would not be one of those advances. Cast iron castings are (very much so) super, ultra, obscenely finicky, and as most welders would state, an obvious "DON'T" for the alternative of a $165 no-brainer "viable" cast iron casting. Regardless of pre/post heat, using an oven, going nickel based, band sawing an excess outer piece of the casting for use as Tig filler metal rod, and going through the rigamarole of not 1, not 2, but 3 attempts to weld that POS 5,000... It cracked on each post install. First attempt lasted 3-4 weeks, next was about 1 week, the third, of which had *every* aspect of appropriate spiffy convexity/light penetration and surface prep ad-infinitum cracked -DURING- the bolt up.

Obviously, that was it.

I caught a ride to the local O'Reilly's, came back with the fresh, and *HURLED* that bastard into shop dumpster catharsis.

This "Solved" the ****P303**** condition plague.

New Exhaust Manifold quieted all the racket, and no more leaky leaky, no more codey code code.

Unfortunately, that was an: "At that time, in those moments, those months, that year, won't code not *RIGHT NOW* " story.

My harsh lesson of maturation here was: BITE THE BULLET KID, IT'S CAST IRON. (I also had no clue at the time about the existence of hardfacing *powder* surface brazing application to cast irons, etc.)

What "would" have been an absolute memory would then become a fluctuating condition that, based on atmosphere, elevation, and overall engine build "temperment", this code would crop up, then disappear, and then sustain over the course of the following years, all specifically relative to P303 as the problem child. Due to the intermittent nature of the code throwing, my desire not to tear the head off, and previously sheer wanton ignorance of how intimately related cracked manifolds and burned valves are, I sold myself into all manner of other circuitous gymnastics to address everything else possibly related to the code in hope to perform "the mystery" to annihilate the misfire. Recently Previous Maint. In Vehicle Targeting Cylinder #3: coil pack swaps, plug swap, verifying voltage at terminal, exhaust manifold replacement of the replacement w/fresh gaskets, intake manifold cleaning/ fresh gaskets, manifold port cleaning , fuel rail flush, injector swap, verifying injector voltage, camshaft cover service/gasket/spark gaskets, valve train appearance, etc. All confirmed the mechanical seal indication.

Had I been coached toward decarbonizing the acute exhaust valves&seats in question on Cylinder #3 with a course of ultra direct solvent applied in excruciating, agonizing Q TIP detail during that immediate contemporary time frame during the cast iron welding malarkey, I do believe that this calamity could have been absolved completely, and the brutal toll avoided.

So.
Now Some Years Later.

Switching tone to concision:
Said Engine @220,000 miles has 1 specific sustained code: P303.
Absolute Confirmation at the *definitely* burned margin/seat/face with *potential* --deposition-- noted to the ^head^.

Option#1: 17 Head Bolts & 17 Potential TTY Laffy Taffy Snappies.

Option#2: R&R My Dad's Nissan Titan with wheel bearing roar & 16 years of neglect, torch and chisel hubs off, explore Willy Wonka's Wonderland Of Nightmare Schmoo and Dire Gondola of Undulating Seal Failures & NO CRANK and Drive to Ft. Worth from North Georgia. - Dig 6 ignition switches out of Pick-N-Pull Dallas - '06 Titan switches were out *Nationwide*.

(First Titan -> journey -> TB engine foray @ "Riteway Auto Sales" in Munford Alabama for a " " 65K " " 4.2L LL8 2008)
(-AVOID- That engine looked like it'd been dug up. The sludge beneath the cap was no surprise. )
(Y'all looked guilty when I walked in.)

Find a fresh 2008 wreck w/somethin' special In FT. Worth, buy a shop crane in TX, use it to juggle the engine and my heavy shop & tools & stock In Texas into said truck, leave that crane in TX, bring the engine and the shop back to GA, *finish* discovered unfinished weldments on previously purchased GA shop crane lying in sub pair wait, redesign engine stand #2 away from assly bolt configuration designed to mate bolts in pure shear plane w/fresh casters/gusset/elevation.

Begin Fundamental Engine Teardown Review @ Pre Swap

#1 Discover @ Exhaust Manifold Heat Shroud Removal:

-.EXHAUST MANIFOLD VANE ON CYLINDER #3 IS CRACKED.-

-Revel In Amazement-
-Regroup-
-Pray To God-


-I'll pick this up again tomorrow-
:biggrin: !!!CHEERS!!! :biggrin:
 

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808

Original poster
Member
May 5, 2022
209
Georgia
"We've got an engine stand" They said.

-Mad Max : Fury Road - Immortan Joe Evangelical Pamphlet

-Gas Up on engine reception day in Ft. Worth

-The sweet crackle lying in wait beneath the heat shroud of the "Newly Wrecked"
(But Only Fender Bender Status) 185,000 Mile - New Recruit

Tool Appropriation Station HATH COME: x=(MOAR)

Massive Thanks again to @Mooseman & @mrrsm for their exceptional project logs.
-DEEPLY APPRECIATED-

Moar to come.
 

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