Spark plug cross threaded

PiErOe1347

Original poster
Member
Jul 21, 2018
6
Wichita Kansas USA
Specs 2005 trailblazer 4.2L I6 197k miles

This last weekend while replacing my spark plugs I found #5 was crooked... And had a motorcraft platinium AGSF 22WM 9D(shorter threads) spark plug jammed in. So now I need help with reccomendations for an insert kit to repair the threads. The insert kits that I have found are much shorter(1.25 X 14) than the threads for the AC 41-103 spark plug which looks like it needs 2.5 X 14 or so. Any help would be appreciated.
20180721_195453-1.jpg
 

littleblazer

Member
Jul 6, 2014
9,265
Hmm. It would be possible to just use two inserts. I may be thinking helicoil type though.
 

PiErOe1347

Original poster
Member
Jul 21, 2018
6
Wichita Kansas USA
Did it just kill the upper threads?

There's a not-particularly-cheap tool you can get. It drops down the hole, then expands, and lets you chase the threads (starting with the good ones) from the underside!

This is the only one I could find quickly... there are many others!
https://www.lasertools.co.uk/product/5278

Interesting that's the first time I have seen a tool like that, I unfortunately I believe the threads are bad the majority of the way through.


Hmm. It would be possible to just use two inserts. I may be thinking helicoil type though.

I'm not sure if two would work but the length would make sense as long as nothing is hanging down too far. Helicoil seemed to be the favored in pull tests, although timesert seemed to be the favorite pick among people. It held the worst on the pull test I found.
 

littleblazer

Member
Jul 6, 2014
9,265
Interesting that's the first time I have seen a tool like that, I unfortunately I believe the threads are bad the majority of the way through.




I'm not sure if two would work but the length would make sense as long as nothing is hanging down too far. Helicoil seemed to be the favored in pull tests, although timesert seemed to be the favorite pick among people. It held the worst on the pull test I found.
Generally the threads of a helicoil are stronger than what was there originally...
 
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djthumper

Administrator
Nov 20, 2011
14,950
North Las Vegas
Do not try to stack helicoils on top of each other and expect the threads to be lined up. You should be able to find a little deeper helicoil to do the job.
 

mrrsm

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Arguably… the Best Thread Repair Kits in the entire world for this sort of problem are made by the TIME-SERT Company. They make Kits specific to Spark Plug Thread lines by their EXACT Length with the proper Thread Pitch and Thread Count. I have a lot of experience using their Kit designed to repair FUBARed Bolt Holes in the GM LL8 Engine Block to very great success. I suspect that these Spark Plug Kits are not cheap by any means… but probably not in the $500.00 category that their more complex products cost. TIME-SERT inserts Do NOT get adjusted for length...what you "Wind UP" with is a PERFECT REPAIR:

Here is the link to their Main Site:
http://www.timesert.com/html/sparkplug.html

Here is good Basic Demonstration Video:

..and one from the Wurth Company (The Mother Ship for TIME-SERT):
 

mrrsm

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Yes...But... Using the TIME-SERT Kit will "Wind Up" being MUCH less of an Expensive PITA than having to:

(1) Pull The Useless Engine Head
(2) Perform the Spark Plug Hole Repair in a Machine Shop
(3) Completely Replace The FUBARed Engine Head
(4) Re-Install the Repaired/New Engine Head

:>)
 

PiErOe1347

Original poster
Member
Jul 21, 2018
6
Wichita Kansas USA
Thanks everyone. I'll update once I get the kit put in(or try). I got the domestic kit 4412E-187 $244.00 on its way.

P. S. Mooseman Thanks $150 for the service manuals I've used that so many times already.

Feel free to remove need help banner I'm not sure how to.
 
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Mooseman

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Dec 4, 2011
25,317
Ottawa, ON
You're welcome and banner removed.

Please keep us updated. It must have run like crap with the wrong plug like that.
 

mrrsm

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https://www.flickr.com/photos/126111508@N07/albums/72157671220350188/page1

Since I am not alone among the few Members who have been troubled with this very same problem... and conquered that sinking emotional feeling that comes with knowing it must be done... I'll help you with some additional guidance ...if I may:

(1) Foremost in your Mind... before you begin this repair ...is to remember One Word:

PREPARATION

(2) Prepare The Work Field—by obtaining the right kind and height of a Foot Stand to elevate your position stable enough over the Engine Block to be able to stand and look right down inside of the involved Spark Plug Well. Doing this will increase your Mechanical Advantage over all of the tools you will be working with and ensure that your Tap and Thread work occurs at a Perfect Right Angle to the Spark Plug Hole.

(3 Prepare The Work Field-- by obtaining a large Pure White Cotton Terry Cloth Towel to lay around every other area of the top of the engine ...to Isolate the Spark Plug Well. In this manner... all of the Aluminum Sprue that you extricate with the Time-Sert Tap can be wiped off at a distance...and prevent as much of the Aluminum Sprue from failing back down inside of the naked Cylinder/Piston Head Below or invade other open places on the Engine.

(4) Prepare The Tools-- While The Time-Sert Kit might seem like the Most Important Tool involved in this Repairit is NOT The next Tool to obtain will be a Proper Machinist Tap and Die Holder and NOT the inexpensive one from Harbor Freight or anywhere else. I have attached a link to my "Flickr-Bucket" so you can SEE this device In Action performing this very same type of repair, This Tool will properly HOLD the various Taps-Bits firmly enough NOT to allow any wobbly play once you begin to do the work. You will not regret the expense.

(5) Protect the Piston and Cylinder-- The Piston Head must be put in a position lower than the Time-Sert Drill Nose to avoid being Damaged. You will need to use a Very Thick Grease applied to the flutes of the Tap in order to Get the Aluminum Metal Chips, Shavings and Sprue to adhere to the Tool and avoid having this trash dropping down inside of the Cylinder. Work Slowly and ONLY MAKE TWO OR THREE TURNS AT A TIME before unwinding the Tap and CLEANING OUT THAT CRAP WITH A FRESH WIPE RAG AND SOME SPRAY BRAKE CLEANER. Then re-apply Fresh Grease and carefully Re-Thread the Tool Tap down the hole to continue. THIS is the only way to ensure that all of the Aluminum Metal Trash will NOT drop inside of the Cylinder Head. Prepare the means to blow out the Spark Plug Well...Before… During and only Afterwards should you induce the Air Spray Tube down inside of the Cylinder to find and eject any particles of the Aluminum Metal left overs.

(6) Prepare Yourself-- Double Check Your Instructions. The night before you perform this repair… Lay out these Time-Sert Tools and with the Instructions at Hand… Practice going over what you intend to do for real. Walk everything through in Steps … and get familiar with all of them… this Repair is like nothing else you have ever worked with… So your Practice and Familiarity will Make for Perfection ...once you begin this work. READ OVER THE INSTRUCTIONS more than Once and when performed… your work results will be Amazing.

(7) Have Confidence in The Outcome-- You have the support and understanding of all of the Members of GMT Nation behind you in this matter. As daunting as it might seem right now… This Elephant can easily be eaten… if you take it Only One Bite at a Time. Clear your Calendar and Turn Off your Cell Phone. Tell the Wife to take the Kids to a Friend’s house ..or wherever they can be happy and safe for the amount of time it takes to allow you to work uninterrupted. Nosy Neighbors? Shine them on that you have “The Spider Flu” .. or something dreadful like that ...scary enough to shoo them away. And unless you have a Sole, Trusted Friend to assist you possessed of enough Mechanical Chops and Know-How to Keep His Hands in his Pockets and his Mouth Shut once the Operation Begins… Then perform this work by yourself after you Open Up a Fresh Can of PATIENCE... Then you are going to be fine!

Please Visit and View ALL of the images at this link to see how the job gets done. While you will be working essentially blind in the Spark Plug Well… YOUR Tools will be a bit different for the Deep Well Access necessary here... but will also be much less cumbersome to use than the ones needed to perform an R&R of an Engine Block Bolt Hole.

https://www.flickr.com/photos/126111508@N07/albums/72157671220350188/page1

Good Luck, Brother!
 
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PiErOe1347

Original poster
Member
Jul 21, 2018
6
Wichita Kansas USA
Great advice that I'll definitely be using to the fullest extent

1. With about 1 more week til I can do the fix (job permitting 6 days a week trucker) I'll continue studying and practicing the process and procedures outilned.

2. Great idea I usually forget until 10 minutes into jobs lol

3. Great idea I'll even extend with towels to completely covered entire engine compartment.

4. Luckily my dad has a great set for this type of things. Also he usually uses the set on bolt threads so the tools I'll be using will be in great shape.

5. How do I(with some degree of control better than crank and hope) turn the engine over to achieve desired piston position?

6. Will do.

7. Luckily again, I for sure will be doing this alone in a roomy shop with no neighbors for 2 miles at my dads. Sadly I won't get to go home until it's fixed, cured, and back together. We only have this one car so I've been extra careful with doing things to the car. Aside from after pulling the short plug out and going ahead and putting the new one in (probably wasn't the best idea). It has ran fine so far, but I want to fix it right for another 100k miles.
 

mrrsm

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Oct 22, 2015
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Answer to your Number (5) Question:

Normally, this is the Very Best Method and Tool (Innova TDC Tool) in order to find TDC (Top Dead Center) of the Piston Head... and then follow the Graduated Center Rod as it moves downwards during the continued Clockwise Hand-Cranking of the Engine via the Harmonic Balancer Bolt using a Large Socket and a 1/2” Breaker Bar. NEVER turn the inner rotating engine assembly of this or any engine Counter-Clockwise.

Here is what this Innova TDC Tool looks like when fully threaded into the Spark Plug Hole of the #1 Cylinder with the Piston at TDC... Remember... the portion that is touching the Piston Top down inside of the Motor is under internal Spring Tension... so when you get past TDC, that long Brass Tipped Plunger will begin to go DOWN... following the descending Piston.

1532376838925.png

Here is Where to Get One:

https://www.amazon.com/dp/B000FMSU9Q/?tag=gmtnation-20

The Piston only needs to move downwards about one to two inches inside of the Cylinder Bore to be far enough away from the Time-Sert Drill Bit. Use caution with your Hand Drill by carefully controlling the downward pressure and speed. Don't over-do the Pressure... Just Once all the way In ...and Once all the way Out. Before you start... ensure that the Drill Bit Flutes get liberally filled with enough Thick Grease to catch all of the Aluminum Crap being Drilled out, This approach will allow you to avoid damaging the top of the Piston and dropping a handful of the soft, Aluminum detritus down inside of the Cylinder.

If the Innova TDC Tool cannot get any thread purchase inside of the FUBARed Spark Plug Hole... You can also accomplish the very same task inside of this vertical cylinder engine by using a Long McDonald's Soda Straw. Better yet... Think "Crazy Straw" Length here; one that is VERY LONG so it will NOT Drop Down Inside of The Motor... or damage-scratch the Piston Head. Once you locate TDC... mark the outside of the Straw with a Magic marker. The Procedure is the same as for the Innova TDC Tool which, God Forbid... that you would need to perform the TDC Check if it becomes necessary to R&R the Engine Head. But... I certainly hope NOT.

Comment on the Number (7) Question:

A Word to The Wise...If you can avoid having to re-build this Engine Top End ... by all means... follow the KISS Principle and do just exactly that. If you tear this thing completely down and then any other asymmetric problems should develop and interfere with your ability to complete the work within a reasonable time frame... You will be more likely to avoid any interruptions by not tackling the job until your have EVERY LAST THING THAT YOU REQUIRE . Life has a way of throwing Curve Balls at the Guys who can only hit Fast Balls Right out of the Park All Day Long... So just keep an open mind ...and keep your wits about you as you proceed.
 
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Mooseman

Moderator
Dec 4, 2011
25,317
Ottawa, ON
I just stick a screwdriver in the plug hole to see the piston move.
 
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Sparky

Member
Dec 4, 2011
12,927
Yeah, screwdriver works fine. Been there done that.
 

mrrsm

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Oct 22, 2015
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For Stateside access to the TIME-SERT Kit being used for this particular Spark Plug Hole Repair on the GM LL8 4.2L Engine… Amazon carries The Kit as Part# 4412E-187 :

https://www.amazon.com/dp/B01D1R8JK6/?tag=gmtnation-20


Generic Image of the Spark Plug Repair Tools and "Serts"

61tvpChrJ4L._SL1024_.jpg
 
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