Spark Plug question
Thread Starter
Instructor
Joined: Sep 2008
Posts: 233
Likes: 17
From: Macon GA
Spark Plug question
My 2000 Coupe just turned 40,000 miles and is completely stock under the hood; original hoses, belts and spark plugs. I am going to do some preventative maintenance things like replace the hoses and belts and was wondering about replacing the plugs and wires.
I know the book says you need to change the spark plugs only every 100,000 miles but the car is 12 years old. I have heard that plugs will seize to the heads if they are left in too long. Does this refer to miles, years, both, or is this an urban legend?
Do plugs that have been in the heads for 12 years need to be replaced as a preventative maintenance measure even though they only have 40,000 miles on them?
I know the book says you need to change the spark plugs only every 100,000 miles but the car is 12 years old. I have heard that plugs will seize to the heads if they are left in too long. Does this refer to miles, years, both, or is this an urban legend?
Do plugs that have been in the heads for 12 years need to be replaced as a preventative maintenance measure even though they only have 40,000 miles on them?
Melting Slicks
Joined: Jun 2010
Posts: 2,809
Likes: 3
From: Yorktown Virginia
I dont see a problem in you replacing them at 40k but there is probably no need in it unless you are worried about them seizing. I had no trouble at all getting mine out and I had ~103k on it when I did them earlier this year. Just change them on a cold engine and you should be fine, I let mine sit over night just to be sure and I was putting headers on so I had the time.
Melting Slicks
Joined: Jan 2007
Posts: 2,170
Likes: 6
From: Oilerville Edmonton
St. Jude Donor '08
I changed the plugs on my 2000 this spring at about 55k miles on it. the plugs were in terrible shape. the gaps were waaaay out. you may want to pull the plugs and look at them. if they look fine, add some anti seize and put them back. since you've gone to all the trouble of puling them, you'll likely want to replace them though. also, you'd better plan to put new wires on. some on here got them off without damaging them but most haven't. I also did the change while I was installing headers.
Drifting
Joined: Dec 2002
Posts: 1,474
Likes: 4
From: Tracy CA
AC Delco 41-110. They don't lose pucks and last forever. I just inspected mine at 90,000 miles. They still look great and went right back in.
Edit - I also use anti-seize.
Edit - I also use anti-seize.
Last edited by mitchcole; Dec 17, 2011 at 01:00 PM.
Tech Contributor
Joined: Jan 2007
Posts: 19,115
Likes: 1,038
From: Dyer, IN
Are you suggesting that after doing a head/cam upgrade(with all that work involved) to increase performance, that you reused 90K mile spark plugs??
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 326
From: CA.
St. Jude Donor '13-'14-'15
NO it's not a myth---If you don't remove them every 30k or so the carbon builds up on the threads and the sorta weld themselves into the heads---On Fords with the "high thread model pulgs "they actually will break off in the head--rare on an Ls engine but I've seen it happen as well---Yes replace the wires too--- Both miles and age allow them to deteriorate
GM make some nice performance wires avail at the dealer--they are red in color---To me the best plugs you can buy is the NGK TR-55---It's a basic copper core plug but copper is the best material to remove heat from a plug--the new popular alternate material plugs don't add any HP--that is a myth--they only add longivity-but it's a catch 22 as you still should remove them to break them loose every 30k miles or so---So why not use the more engine friendly copper cores gap the TR-55's at .040
GM make some nice performance wires avail at the dealer--they are red in color---To me the best plugs you can buy is the NGK TR-55---It's a basic copper core plug but copper is the best material to remove heat from a plug--the new popular alternate material plugs don't add any HP--that is a myth--they only add longivity-but it's a catch 22 as you still should remove them to break them loose every 30k miles or so---So why not use the more engine friendly copper cores gap the TR-55's at .040
Melting Slicks
Joined: Jun 2010
Posts: 2,809
Likes: 3
From: Yorktown Virginia
NO it's not a myth---If you don't remove them every 30k or so the carbon builds up on the threads and the sorta weld themselves into the heads---On Fords with the "high thread model pulgs "they actually will break off in the head--rare on an Ls engine but I've seen it happen as well---Yes replace the wires too--- Both miles and age allow them to deteriorate
GM make some nice performance wires avail at the dealer--they are red in color---To me the best plugs you can buy is the NGK TR-55---It's a basic copper core plug but copper is the best material to remove heat from a plug--the new popular alternate material plugs don't add any HP--that is a myth--they only add longivity-but it's a catch 22 as you still should remove them to break them loose every 30k miles or so---So why not use the more engine friendly copper cores gap the TR-55's at .040
GM make some nice performance wires avail at the dealer--they are red in color---To me the best plugs you can buy is the NGK TR-55---It's a basic copper core plug but copper is the best material to remove heat from a plug--the new popular alternate material plugs don't add any HP--that is a myth--they only add longivity-but it's a catch 22 as you still should remove them to break them loose every 30k miles or so---So why not use the more engine friendly copper cores gap the TR-55's at .040
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Le Mans Master
Joined: Mar 2002
Posts: 5,955
Likes: 161
From: PNW
GM make some nice performance wires avail at the dealer--they are red in color---To me the best plugs you can buy is the NGK TR-55---It's a basic copper core plug but copper is the best material to remove heat from a plug--the new popular alternate material plugs don't add any HP--that is a myth--they only add longivity-but it's a catch 22 as you still should remove them to break them loose every 30k miles or so---So why not use the more engine friendly copper cores gap the TR-55's at .040
See #5 in link below:
http://www.ngksparkplugs.com/pdf/DYK_5Points.pdf
Other spark plug tech info from NGK.
http://www.ngksparkplugs.com/tech_su...w.asp?mode=nml
Le Mans Master
Joined: Mar 2002
Posts: 5,955
Likes: 161
From: PNW
BTW - TR-55s are factory gapped at 0.060" and TR-5s are the same spark plug, except they are factory gapped at 0.040". No use gapping TR-55s down from 0.060" to 0.040" when you can buy TR-5s already factory gapped at 0.040".
Last edited by ZeeOSix; Dec 16, 2011 at 05:35 PM.
Safety Car
Joined: Jul 2005
Posts: 3,572
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From: Jackson Tn
St. Jude Donor '06-'07-'08-'09
So why are "copper core" TR-55s more "engine friendly" when all NGKs are copper core?
BTW - TR-55s are factory gapped at 0.060" and TR-5s are the same spark plug, except they are factory gapped at 0.040". No use gapping TR-55s down from 0.060" to 0.040" when you can buy TR-5s already factory gapped at 0.040".
BTW - TR-55s are factory gapped at 0.060" and TR-5s are the same spark plug, except they are factory gapped at 0.040". No use gapping TR-55s down from 0.060" to 0.040" when you can buy TR-5s already factory gapped at 0.040".
Drifting
Joined: Apr 2011
Posts: 1,454
Likes: 6
From: Pittsburgh PA
Changed mine (and the wires) at 71,000 simply because the engine was sitting on the floor. No problems removing them, threads were fine and the plugs didn't look much different than the new ones. I have no reason to believe they wouldn't go the 100k. Mines a 99 BTW.
If you decide to change them, figure on wires too. Not cause they are bad but they are a bugger to get off without pulling them apart.
What is the purpose of gapping at .040 when the manual calls for .060 ?
If you decide to change them, figure on wires too. Not cause they are bad but they are a bugger to get off without pulling them apart.
What is the purpose of gapping at .040 when the manual calls for .060 ?
Melting Slicks
Joined: Jun 2010
Posts: 2,809
Likes: 3
From: Yorktown Virginia
Changed mine (and the wires) at 71,000 simply because the engine was sitting on the floor. No problems removing them, threads were fine and the plugs didn't look much different than the new ones. I have no reason to believe they wouldn't go the 100k. Mines a 99 BTW.
If you decide to change them, figure on wires too. Not cause they are bad but they are a bugger to get off without pulling them apart.
What is the purpose of gapping at .040 when the manual calls for .060 ?
If you decide to change them, figure on wires too. Not cause they are bad but they are a bugger to get off without pulling them apart.
What is the purpose of gapping at .040 when the manual calls for .060 ?
Tech Contributor
Joined: Jan 2007
Posts: 19,115
Likes: 1,038
From: Dyer, IN
Changed mine (and the wires) at 71,000 simply because the engine was sitting on the floor. No problems removing them, threads were fine and the plugs didn't look much different than the new ones. I have no reason to believe they wouldn't go the 100k. Mines a 99 BTW.
If you decide to change them, figure on wires too. Not cause they are bad but they are a bugger to get off without pulling them apart.
What is the purpose of gapping at .040 when the manual calls for .060 ?
If you decide to change them, figure on wires too. Not cause they are bad but they are a bugger to get off without pulling them apart.
What is the purpose of gapping at .040 when the manual calls for .060 ?
Tech Contributor
Joined: May 2008
Posts: 2,843
Likes: 16
From: Howell Michigan
St. Jude Donor '09-'10-'11
I know the book says you need to change the spark plugs only every 100,000 miles but the car is 12 years old. I have heard that plugs will seize to the heads if they are left in too long. Does this refer to miles, years, both, or is this an urban legend?
Do plugs that have been in the heads for 12 years need to be replaced as a preventative maintenance measure even though they only have 40,000 miles on them?
Do plugs that have been in the heads for 12 years need to be replaced as a preventative maintenance measure even though they only have 40,000 miles on them?
#PIP3069C: Information - Iridium and Platinum Tip Spark Plug Maintenance - keywords 30K major minor preventative removal remove replacement tune up - (Apr 4, 2006)
Subject: Information - Iridium and Platinum Tip Spark Plug Maintenance
Models: All GM Passenger Cars and Trucks
with Iridium or Platinum Tipped Spark Plugs
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
The information below was originally sent to all GM Dealers on October 14, 1999 as a DCS message. This information applies to all vehicles equipped with Iridium or Platinum Tipped Spark Plugs.
Recommendation/Instructions:
Iridium and Platinum tipped spark plugs are designed to operate under normal vehicle operating conditions for up to 100,000 miles (160,000 kilometers) without periodic maintenance. As stated in the owner's manual, maintenance needs may vary because of all the different ways people use their vehicles. As a result, more frequent inspections and replacements may be needed if the vehicle is operated in extreme conditions.
When no engine performance concerns are present, Iridium and Platinum tipped spark plugs should not be removed for periodic inspection and cleaning of threads, doing so may compromise the spark plug's ability to withstand their corrosive environment. The threaded area, although not sealed, serves as a protective environment against most harmful elements. Removing and cleaning spark plugs will introduce metallic debris and brush scrapings into the thread area which may further the corrosion process.
Chromate coated spark plugs should not be wire brushed or handled in any way once they are put in service. Chromium topcoats form a protective oxide on spark plugs that is not effective if scratched. Both coated and uncoated spark plugs will have the best chance of surviving a corrosive environment if they are left in position. Attempts to maintain spark plugs by removing them and cleaning the threads can actually create the corrosive condition that the procedure was intended to prevent.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
Last edited by Eric D; Dec 17, 2011 at 01:10 PM.
Drifting
Joined: Dec 2002
Posts: 1,474
Likes: 4
From: Tracy CA
Tech Contributor
Joined: Jan 2007
Posts: 19,115
Likes: 1,038
From: Dyer, IN
In your case, I'm not sure if it's being cheap, ignorance, or being stubborn. My point is simple. If you are going through all the labor and expense to do a head/cam upgrade, it would lead one to believe, that there is some sort of performance goal in mind.
In this case, based on the parts you have installed, you will establish a new performance baseline. This means you start fresh with plugs, plug wires, and fuel/air filter (minimum). It makes absolutely no sense, to have a tune done without knowing these basic parts are fresh (again, considering you are establishing a new baseline).
So go ahead and cut your corners up front, and do your head scratching later......
Good luck......
Le Mans Master
Joined: Mar 2002
Posts: 5,955
Likes: 161
From: PNW
Tech Contributor
Joined: Jan 2007
Posts: 19,115
Likes: 1,038
From: Dyer, IN
Le Mans Master
Joined: Mar 2002
Posts: 5,955
Likes: 161
From: PNW
Chromate coated spark plugs should not be wire brushed or handled in any way once they are put in service. Chromium topcoats form a protective oxide on spark plugs that is not effective if scratched. Both coated and uncoated spark plugs will have the best chance of surviving a corrosive environment if they are left in position. Attempts to maintain spark plugs by removing them and cleaning the threads can actually create the corrosive condition that the procedure was intended to prevent.
The only spark plugs that might need wire brush cleaning and anti-seize are the ones with black oxide coated or non-coated threads.