P0305, AWD failure, and loss of cruise control

[TollKeeper]

I am not certain a valve cover gasket change is in order..

If a valve cover gasket was needed, your spark plug wells would be full of oil

Your appear to be water logged. That means the gasket on the bottom of the coil is the culprit.

 

[HMan_Rainier]

There was some oil on the spark plug on cylinder 3, and it looked like it had spashed onto the coil too. But it was not a ton of oil - maybe around a teaspoon.

I've read people saying that can be normal with these engines - is that true? And if its on top by the coil too is that enough to start worrying about the valve cover gasket?
Would you expect to see oil on all, or at least most, of the plug wells if the gasket had gone bad?

 

[mrrsm]

As for performing what should seem like a very straightforward Valve Cover Gasket R&R... doing so on these Atlas Engines gets to be "A LONG ROAD...WITH NO TURNS...". The process is complicated by the need to remove the Throttle Body and Intake Manifold and work around a Weird Harness Brace and PCM Wiring on the Driver's Side of the Engine Bay (and perhaps, working through the Driver's Side Wheel Well). THIS Thread itemizes the OP's 13 Hour efforts:

Valve cover gasket replacement on 4.2L

I got some oil in #3 spark plug well so the infamous gasket is beginning to leak. I read a post that talks about the valve cover gasket and how to change it. It has good detail but one thing I didn't read was anything about the 2 hoses that wrap around valve cover at the firewall end of the...

gmtnation.com

Some More Information:

The Oil is definitely leaking in from around the "Pear Shaped" "O" Ring Like Grommets surrounding the Spark Plug Wells... Not from the Likewise Pear-Shaped Foam Seals around the Coil Over Plug COPS. To illustrate the issues, consider that back in 1998, the GM Atlas LL8 Engine Design Team (under Mr. Ron Kociba) decided that rather than use the Old Cork or Rubber Style Valve Cover gaskets of old (265, 283, 307, 327, 350 CID Motors) they took a novel approach by "Never Allowing the Valve Cover to EVER actually Touch the Aluminum Head... NOR Allowing the Fasteners to Directly Touch the Valve Cover."

They were Clever Dudes, Yes? They arrayed (21) of these Trapped Fasteners around the perimeter and when calculating 21 X 89 Inch Pounds of FORCE...Well ...You can get the Idea that regardless of Engine Temperature and the radical expansion and contractions that the Aluminum Head experiences over its operational life... when properly installed (and "PLUMP") this is a VERY successful method for joining the Valve Cover atop the Engine Head... and almost NEVER having the two loosen or separate their seals. :>)

They did this using a unique "O" Ring Style hemispheric outer shape nested into the Valve Cover with an "I" Beam like shape holding them buried deep into the Outer Valve Cover Inlay Slotting. And for the Fasteners...they opted to stabilize the Torque need to fix the two items together... almost floating... by spreading out a uniform mere 89 Inch Pounds of Torque around the Outer Rim and thus achieved a HUGE, Squeeze Down Force that would simply Bottom Out the Inner Steel Trapped Fasteners into the Upper Engine Head... and still allow the Valve Cover to literally "Float" upon those squished down, half-moon shaped "O" Ring Seals.

However... as mentioned by @Chickenhawk ... Excessive Engine Vibrations from Failed Gel-Filled Motor Mounts will shake the Valve Cover back and forth enough over time to gradually flatten out and wear down those rounded outer shapes and allow the Combustion Blow-By Gasses and Engine Oil Cast Off by the the Rotating Camshaft Hardware to eventually force their way inside and even fill the Spark Plug Chambers by and by with a LOT of Motor Oil and the other by-product that is always created when Burning Gasoline...Water Vapor. Thus, that Upper Primary Cadmium Plated Coil Over Plug Cover showed the evidence of the second possible source of the invading Water Vapor ...as RUST.

Here are some Images to bear out these observations:



And THESE Videos take you visually through the R&R Steps from a few different approaches, while providing More Proof of what is causing the Oil to Invade inside those Spark Plug Wells:

THIS Dude has a Great look at the differences in the "PLUMPNESS" of the Before vs. the After Views of the New vs. the Old, Sloppy, Worn Flat Gaskets once they are fully pressed into place. Be Fastidious when doing this part... You don't want to casually install any of them and it DOES take a bit of effort to do this part of this Non-Trivial Job...RIGHT:

And more information about "Blow-By":

So... Performing this involved job should NOT be attempted without considering these issues if you don't feel comfortable "Doing ALL THIS Dirty Work..."

Oh...And do the Intake Manifold Swap of the Three Figure Eight Gaskets on the Intake Manifold as well...again...Same "Trapped Fastener" Design and Caution to use ONLY 89 Inch Pounds on them.

 

[Mooseman]

If you have oil in the plug well, it's the gasket. Worse part is removing the intake manifold. Try my washer trick first. Might just give that little extra pressure to reseal it.

 

[HMan_Rainier]

Would I only put the washer on the #3 coil (the one with oil), or on all of them?

 

[Mooseman]

Might as well do it to all of them. If one is leaking, the others aren't too far behind.

 

[mrrsm]

Given the remaining possibility of having isolated issues with the EFI serving in the #5 Cylinder… in lieu of using an Oscilloscope for Testing the ELECTRICAL behavior of the Circuit… Using a NOID LIGHT would also be useful as a Diagnostic Tool when looking for the following potential artifacts of failure:



IF THE NOID LIGHT DOES NOT FLASH:

(1) If you can physically palpate the body of the EFI… you might notice that you not only can Hear the EFI Clicking… but You can sense it Clicking under your finger tips... or NOT.

(2) Once the NOID Light is installed into the Harness Connector, if the LIGHT DOES NOT FLASH… Check for Power on the Circuit… OR ...Check the Control Wires for OPENS.

(3) Check that the PCM Driver is functioning properly ….AFTER… Verifying that there is POWER at the EFI… AND ... Measure the DC Voltage AT THE PCM on the EFI Control Wire with a KNOWN GOOD INJECTOR. If SYSTEM VOLTAGE is present, it means there is a Problem with the PCM Driver. But, if you measure “0” Volts at the PCM, it means the Control Wire is having an OPEN Circuit .

IF THE NOID LIGHT FLASHES:

(1) It means the the Electrical Circuit is sound, but the EFI is BAD.

IF THE NOID LINE STAYS ON ALL THE TIME:

(1) The EFI will have a CONSTANT SPRAY, creating an Excessive RICH Condition

(2) Check for a SHORT TO GROUND on the Control Wire at the EFI.

(3) Check for a Shorted PCM Driver by Un-Plugging the PCM with the KOEO (Key On Engine OFF) if the NOID Light Goes OUT… It means the PCM Driver is SHORTED.

(4) Check for a Shorted PCM Driver by Un-Plugging the PCM with the KOEO (Key On Engine OFF) if the NOID Light stays ON… It means the Control Wire has a SHORT TO GROUND.

Follow all of this NOID Light Diagnostic Logic as explained by Paul "Scanner" Danner during an Automotive Training School Session at Rosedale College:

EDIT:

Forgot to mention that the Felpro Valve Cover Gasket Set (inclusive of the 21 Fastener Grommets) is available now at 51% Off on Wednesday June 7th, 2023 over on Amazon via THIS Link:

https://www.amazon.com/dp/B000HURIX0/?tag=gmtnation-20

 

[mrrsm]

An important follow up to Post #43 and Post #47 concerns what you will GET if you have the chance to decide between ordering either the GM OEM Valve Cover Gasket Kit vs. ordering the Felpro Version. The distinctions between them are NOT trivial if you intend to be thorough in "rebuilding" the Valve Cover AFTER soaking it in a 50/50 solution of Purple Power Carbon and Oil Busting Hot Water Bath... submerged long enough to dissolve and dislodge anything that might prevent seating these gaskets correctly and avoid inadvertent Oil Leaks:

THIS is all you get when you order the ACDelco GM 4.2L Valve Cover Kit. Notice... There is NO collection of the Requisite (21) Trapped Fastener Grommets included here. There is also no explanation or description of WHY the Six Pear Shaped Isolation Gaskets for the Spark Plug Wells are BLACK... while the Valve Cover Outer Perimeter Gasket is GRAY. :




Compare THAT to this thoughtful and complete arrangement and packaging of the Felpro GM 4.2L Valve Cover Gasket linked back in Post #43 and Post #47 to the Amazon "51% OFF" Sale:



Choose Wisely... :>)

 

[mrrsm]

Amazon has THIS NOID Light Test KIt available for Under $20.00:

https://www.amazon.com/dp/B0028QGU6C/?tag=gmtnation-20

Here is what the Gear Looks Like:



...and HERE is the GEAR ...In ACTION on a Chevrolet Tahoe:

And here sis a GREAT WHITE BOARD IFI OPERATIONAL EXPLANATIONl... on a Honda Transverse Engine WITH a FUBAR'd EFI...? (...Maybe...) NOID Light vs. Incandescent Test Light vs. Using a Power Probe 4 with a Built-In EFI Mode instead:

 

[HMan_Rainier]

Well, bad news.
Decided to get a compression test just to rule that out and it was way down on #5.
Pulling the head is well beyond my ability, so brought to a trusted shop.
The carbon build up was absolutely insane, and if you held up a flashlight to the valve you can see through it.
Head bolts snapped (expected) but they having a really hard time getting them out and they are worried about damaging the aluminum block, so right now it's looking like I might be putting a whole new engine in - Good times.

 

[Mooseman]

Ya. For the cost of the work and machining, it's actually easier to replace the whole engine. It can be done, just a lot of work. For the best results, there is a special tool to remove the broken head bolts from this engine. And if there are a lot of them, you're still ahead to replace the whole thing.

 

[TollKeeper]

Yea... Do the whole engine.. Low mile versions are still out there.

There was a 04 Trailblazer in my local yard with 70k miles. T-boned hard in the drivers side.

I doubt its still there, and I dont know what year you have.

 

[TollKeeper]

Found it.. 2005 Buick..

Whole truck for 850. Sounds like its rusted out pretty good. 171k.

2003 Chevy Trailblazer LTZ - auto parts - by owner - vehicle...

FOR PARTS/AS IS !!!! 2003 Chevy Trailblazer LTZ Odometer: 171,661 Transmission: Automatic No Lights are on in the car but has problems. Car starts and can drives but has work thats needed in order...

southcoast.craigslist.org

Whole truck for 650. Sounds like its rusted out pretty good. 121k.

Dam Shame..2003 GMC Envoy - auto parts - by owner - vehicle...

Fully loaded 112K 3rd owner. Still registered but unable to sticker. Still drive able but needs metal work

boston.craigslist.org

and others.

I might be interested in some parts off the 650 truck, if the interior is in good shape.

 

[HMan_Rainier]

Wanted to give an update for posterity if anyone is looking at this in the future.

Ended up having the shop I go to put a new to me engine in from a local yard. It cost about 4400 all said and done, which was honestly better than expected.
It is absolutely wild how much smoother the idle and ride is, and the computer is reporting about 2mpgs better across the board - haven't had to chance to calculate it to confirm that yet. I love this car and it is so clean, I am confident it was worth the replacement.

I put a new encoder motor on the transferase, which seems to have solved that problem and the AWD is working like it should.

Thank you for everyone who helped me figure this all out, it's a bummer that I had to get another engine, but I am glad that it is working like it's supposed to and I have my car back!

 

[mrrsm]

I've been thinking about One, Last Ditch Effort to change the dynamics of the dissimilar metals between the Mild Steel Spark Plug Threads vs. the Female Aluminum Threads inside of the Engine Head:

How about Drowning the Spark Plug in THIS Stuff for just a Few Minutes and then trying to unwind it ...very carefully. If this Chemical gets COLD enough ...SOON enough ...it just might work to Shrink the Plug enough to Break it LOOSE:

https://www.amazon.com/dp/B000KKCQUW/?tag=gmtnation-20