Question about the spark plug threads in the cylinder head - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Kiowa88 · 11-06-2011, 02:46 PM

Just curious to know the probability of the threads being cross threaded from the factory. Pulled the factory plug out, and threaded the new one until it was seated. No unusual resistance seeing as how the other 7 went it without a snag. Well I thought it was fully seated. Turns out about half the threads where cross threaded and mangled with the plug in just far enough to appear ok. Ran into this nasty suprise during my cam swap.

Russell James · 11-06-2011, 03:10 PM

Normally when cross threaded, it will be very hard to pull out the entire thread distance. And the plug will be in at a funky angle with a compression puff puff noise.

Have you tried a thread chaser? Auto parts stores will have a spark plug thread chaser. Put some grease in the groove and crank it in. I've fixed several just chasing the threads. If it won't hold tq after that, then a heli-coil is needed.

BowlingSS · 11-06-2011, 03:12 PM

I have never heard of threads messed up from the factory but it could of happen. Good luck on the fix.

Bill

bannonm · 11-06-2011, 05:23 PM

I would think you would have leakage around the plug if it were cross-threaded from the factory. I am assuming you have been driving the car for a while?

A few tips for replacing plugs. Always use anti-seize and always start the plug by hand. Meaning start the thread using only your fingers so you know it's going in correctly. You may need to use the plug socket and an extension and spin it in by hand if you can't reach the threads, but never use a ratchet to start a plug. Hope it works out for you.

Kiowa88 · 11-06-2011, 06:58 PM

Thanks for the suggestions. I really appreciate it. I ended up pulling the head off. I've never done a heli-coil before so I'm going to take it to my machine shop. Thanks again guys!

MikeOD · 11-06-2011, 10:03 PM

It's very unlikely to be factory cross-threaded...they are tapped on CNC machines, not by hand. What is more likely, is a damaged thread on a new plug causing a problem with a head, or (not trying to be mean to you) operator error when changing the plugs.

Juiced1 · 11-06-2011, 10:07 PM

Quote:

Originally Posted by Kiowa88

Thanks for the suggestions. I really appreciate it. I ended up pulling the head off. I've never done a heli-coil before so I'm going to take it to my machine shop. Thanks again guys!

Might as well get them ported while they are there.

Kiowa88 · 11-06-2011, 10:11 PM

Haha no offense taken. Either way I got to spend the better part of the past three weeks taking this engine apart and putting her back together. Some serious bonding time. I think I'll be able to do this blind-folded soon!

11-06-2011, 02:46 PM	#1
Kiowa88 Out Front! Drives: OH-58D (R) Join Date: Jan 2011 Location: Savannah, GA Posts: 139 View My Garage	Question about the spark plug threads in the cylinder head Just curious to know the probability of the threads being cross threaded from the factory. Pulled the factory plug out, and threaded the new one until it was seated. No unusual resistance seeing as how the other 7 went it without a snag. Well I thought it was fully seated. Turns out about half the threads where cross threaded and mangled with the plug in just far enough to appear ok. Ran into this nasty suprise during my cam swap. __________________ B Troop, 3-17CAV - Out Front

11-06-2011, 06:58 PM	#5
Kiowa88 Out Front! Drives: OH-58D (R) Join Date: Jan 2011 Location: Savannah, GA Posts: 139 View My Garage	Thanks for the suggestions. I really appreciate it. I ended up pulling the head off. I've never done a heli-coil before so I'm going to take it to my machine shop. Thanks again guys! __________________ B Troop, 3-17CAV - Out Front

11-06-2011, 10:03 PM	#6
MikeOD Drives: 2010 M6 2SS Join Date: Mar 2011 Location: South Windsor, CT Posts: 1,202	It's very unlikely to be factory cross-threaded...they are tapped on CNC machines, not by hand. What is more likely, is a damaged thread on a new plug causing a problem with a head, or (not trying to be mean to you) operator error when changing the plugs. __________________ 2010 Camaro SS M6. Heads/Cam/Intake/Headers/Exhaust/Suspension

11-06-2011, 10:11 PM	#8
Kiowa88 Out Front! Drives: OH-58D (R) Join Date: Jan 2011 Location: Savannah, GA Posts: 139 View My Garage	Haha no offense taken. Either way I got to spend the better part of the past three weeks taking this engine apart and putting her back together. Some serious bonding time. I think I'll be able to do this blind-folded soon! __________________ B Troop, 3-17CAV - Out Front

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11-06-2011, 03:10 PM	#2
Russell James Drives: '15 SS 1LE, '69 Z28 drag car Join Date: Dec 2009 Location: Mich Posts: 4,482	Normally when cross threaded, it will be very hard to pull out the entire thread distance. And the plug will be in at a funky angle with a compression puff puff noise. Have you tried a thread chaser? Auto parts stores will have a spark plug thread chaser. Put some grease in the groove and crank it in. I've fixed several just chasing the threads. If it won't hold tq after that, then a heli-coil is needed.

11-06-2011, 03:12 PM	#3
BowlingSS Camaro Owner Since 1987 Drives: 2011 2SS/RS L99 RJT Join Date: Jun 2006 Location: Lawrenceville, GA Posts: 2,185	I have never heard of threads messed up from the factory but it could of happen. Good luck on the fix. Bill

11-06-2011, 05:23 PM	#4
bannonm Drives: 2011 2SS/RS M6 VR Join Date: Aug 2011 Location: Chicagoland Posts: 1,536	I would think you would have leakage around the plug if it were cross-threaded from the factory. I am assuming you have been driving the car for a while? A few tips for replacing plugs. Always use anti-seize and always start the plug by hand. Meaning start the thread using only your fingers so you know it's going in correctly. You may need to use the plug socket and an extension and spin it in by hand if you can't reach the threads, but never use a ratchet to start a plug. Hope it works out for you.