sparkplug thread heli-coil?
Thread Starter
Advanced
Joined: Aug 2006
Posts: 96
Likes: 0
From: Spokane Washington
sparkplug thread heli-coil?
I changed sparkplugs today and ran into a problem. #2 plug appears to be held by some type of cream colored putty. The hole is filled all around the body of the plug. I'm guessing the po stripped out the threads. The car is a 91 L98 and has 40,000 miles.
I left the #2 plug untouched. Assuming I run into a thread problem, does anyone have any experience with inserting a heli-coil?
Thnaks for the help. Gary R
I left the #2 plug untouched. Assuming I run into a thread problem, does anyone have any experience with inserting a heli-coil?
Thnaks for the help. Gary R
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
No, I've never used a heli-coil in a spark plug hole, but I have in a block's head bolt hole.
Only time I had a spark plug hole thread problem I used a thread chaser to clean up the stock threads. Worked like a charm.
Jake
Only time I had a spark plug hole thread problem I used a thread chaser to clean up the stock threads. Worked like a charm.
Jake
Melting Slicks
Joined: Apr 2002
Posts: 2,118
Likes: 0
From: St. Charles, MO Route 66 Corvette Club
Gary: The putty material you see may be anti-sieze compound. This is a lubricant that is commonly used when you insert steel threads into aluminum material. I am confused with the term "cream colored" material. Anti-sieze is usually silver in color and has the consistancy of tooth paste. Did you find this cream colored material on the other seven plugs?
Team Owner
Joined: Jan 2003
Posts: 20,297
Likes: 240
From: Summerland B.C. Canada
I have used a heli-coil insert before, it's not like a typical helicoil as it's a solid threaded insert. I was able to do the repair on the vehicle. It was not a vette, but it was an aluminum head. 
Safety Car
Joined: Jul 2001
Posts: 4,871
Likes: 15
From: Detroit's West Side MI
Heli-coils are a gift from above.
I guess given the option I wouldn't want to use one on a spark plug hole, I'd try the suggestion of cleaning up the threads with a tap first.
But if you have to do so, I don't see why it wouldn't work.
I have one on my aluminum flywheel, it's held strong for two years of racing now...and the clutch / flywheel oviously see extreme temps and abuse.
The only thing I'd worry about is getting a perfect seal, you don't want to lose compression because a plug is cross threaded.
I guess given the option I wouldn't want to use one on a spark plug hole, I'd try the suggestion of cleaning up the threads with a tap first.
But if you have to do so, I don't see why it wouldn't work.
I have one on my aluminum flywheel, it's held strong for two years of racing now...and the clutch / flywheel oviously see extreme temps and abuse.
The only thing I'd worry about is getting a perfect seal, you don't want to lose compression because a plug is cross threaded.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
Le Mans Master
Joined: Dec 2004
Posts: 5,488
Likes: 1,352
http://www.sjdiscounttools.com/kdt3545.html
Here's a back tap it goes down into the sparkplug hole and rethreads the hole comming out so you aren't dumping metal shavings into the cylinder.
Here's a back tap it goes down into the sparkplug hole and rethreads the hole comming out so you aren't dumping metal shavings into the cylinder.
Safety Car
Joined: Jul 2001
Posts: 4,871
Likes: 15
From: Detroit's West Side MI
But...how do you get it in there? Does it somehow expand once you stick it through?
Le Mans Master
Joined: Dec 2004
Posts: 5,488
Likes: 1,352
Thread Starter
Advanced
Joined: Aug 2006
Posts: 96
Likes: 0
From: Spokane Washington
Sam,
Thanks for the reply. The other plugs did not have the cream colored putty around them and they came out without any problem. The anti-seize compound I used was silver in color. I was afraid to disturb the putty around #2 until I talked to you guys and a mechanic I trust. I hope it is not an epoxy or something similar.
I talked to my mechanic today and he has done a number of heli-coil inserts. I think I'll take it to him so that it can be cleaned out and chase the threads or what ever is needed. He'll have all the tools on hand and has had experience with such problems. I probably better hold on to my shorts.
Gary R
Thanks for the reply. The other plugs did not have the cream colored putty around them and they came out without any problem. The anti-seize compound I used was silver in color. I was afraid to disturb the putty around #2 until I talked to you guys and a mechanic I trust. I hope it is not an epoxy or something similar.
I talked to my mechanic today and he has done a number of heli-coil inserts. I think I'll take it to him so that it can be cleaned out and chase the threads or what ever is needed. He'll have all the tools on hand and has had experience with such problems. I probably better hold on to my shorts.
Gary R
Gary: The putty material you see may be anti-sieze compound. This is a lubricant that is commonly used when you insert steel threads into aluminum material. I am confused with the term "cream colored" material. Anti-sieze is usually silver in color and has the consistancy of tooth paste. Did you find this cream colored material on the other seven plugs?
Le Mans Master
Joined: Dec 2004
Posts: 5,488
Likes: 1,352
Sam,
Thanks for the reply. The other plugs did not have the cream colored putty around them and they came out without any problem. The anti-seize compound I used was silver in color. I was afraid to disturb the putty around #2 until I talked to you guys and a mechanic I trust. I hope it is not an epoxy or something similar.
I talked to my mechanic today and he has done a number of heli-coil inserts. I think I'll take it to him so that it can be cleaned out and chase the threads or what ever is needed. He'll have all the tools on hand and has had experience with such problems. I probably better hold on to my shorts.
Gary R
Thanks for the reply. The other plugs did not have the cream colored putty around them and they came out without any problem. The anti-seize compound I used was silver in color. I was afraid to disturb the putty around #2 until I talked to you guys and a mechanic I trust. I hope it is not an epoxy or something similar.
I talked to my mechanic today and he has done a number of heli-coil inserts. I think I'll take it to him so that it can be cleaned out and chase the threads or what ever is needed. He'll have all the tools on hand and has had experience with such problems. I probably better hold on to my shorts.
Gary R
