Triton170

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?

m6 c5

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.

00 Rooster

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.

Triton170

Thanks for the help/info.

I think I will go ahead and replace the plugs and the wires.

mitchcole

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.

lucky131969

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??

tblu92

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

m6 c5

I can see the carbon build up being a problem as when I changed the plugs on the el camino it had a small amount, However I didnt have any the plugs on my 02 when I pulled them out for the header install. In fact they looked pretty darn good especially for having 102k on them and probably would have worked fine to put them back in there but for less than 10$ you can get new ones.

ZeeOSix

Per NGK's website, all their plugs are "copper core". Platinum or iridium plugs just have that special material in the areas the spark jumps across the gap to ensure plug gap longevity.

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

ZeeOSix

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".

printmanjackson

I run the TR-55 gapped at .055

fendermender

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 ?

m6 c5

I seem to remember reading it had to deal with better spark in the higher rpm.

lucky131969

Because it changed with the plugs....

Eric D

Yes to it being a urban legend. You are best NOT to Mess with them. Do not use anti-seize, do not wire brush the plugs..

#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.

mitchcole

as you can tell - there is a difference in perspective between the two of us. I don't fix what isn't broken, you...

lucky131969

How right you are. I have an illustrious history, of advising forum members to just change parts for no reason whatsoever.....so I can see how you would come to that conclusion.

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......

ZeeOSix

The gap changing from 0.060" to 0.040" doesn't seem to be spark plug specific, as NGK is saying all spark plugs they make for the LS1/LS6 applications are all now gapped at 0.040".

lucky131969

How so? The TSB calls out the exact part number for the spark plug. It does not get more specific than that.

ZeeOSix

To add, if you go to NGK's website and read some of their tech info on spark plugs, they also say that the threads on their plugs are coated to prevent corrosion and seizing, and that is why they do not recommend anti-seize on any of their spark plugs.

The only spark plugs that might need wire brush cleaning and anti-seize are the ones with black oxide coated or non-coated threads.