When To Change Spark Plugs

[jefffoxsr]

2003 Yukon has 104,000 miles.

Do the plugs AND wires need to be changed now?

 

Any of you who have pulled them out at 100,000 miles or more how did the plugs and wires look?

 

Were they worn?

 

Thanks

[Stevens03]

Well, GM says they'll last the 100,000 miles and quite frankly I personally haven't made it that far since I trade every 4-5 years. But with that said, I've read from most that about 75,000-100,000 miles is def. a good time to change. And Yes, I'd change both plugs and wires. I've read several say after 75,000 they were due.

 

If your the type to keep your vehicle running in top shape... then I'd certainly change them. Also, I wouldn't use anything other than AcDelo OEM for both.

[Gregs]

I pulled out my factory iridiams at 65000 and they were worn, glad I replaced them. Check the wired for resistance to see if they are bad or not. Be carefull that you dont pull the aluminum threads out of the head if they've been in it for that many miles. I would soak them with pb blaster a day before I went to do the job

[Black02Silverado]

100k is a good time to change out. Mine I did at 75k and they were worn as in had a larger than spec gap. Just remember to change them out with the engine cold so you don't mess up the threads in the head since it is an aluminum head and steel threads on the plugs. Also put just a small amount of anti seize on the threads of the plugs when you put them back in. I also put some dielectric grease on the inside of the spark plug booth. That way it keeps it from sticking to the plug on the next change and keeps any moisture out that might get in.

[RockySierra]

With getting feedback from quite a few mechanics, every single one of them said to get them out of there well prior to 100,000 miles, and suggested that the max they may consider telling a customer to go is 75k. The biggest issue they run into is having plugs "welded" in when they try to remove them at 100,000 miles. Some times this will cause the plug to break or even the threads to strip which causes a whole new set of issues. They suggest removing the plugs at about 50,000 miles to inspect them and see how they are doing. Also, using anti-seize is a big, no no. Causes more problems.

[roegs]

Also, using anti-seize is a big, no no. Causes more problems.

 

 

What was the problem caused by anti-seize? Is there a recommended product for the thread, or should the next set of plugs be installed without anythread compound?

[pm26]

Also, the electrode gap will substantially increase with mileage and the plugs will be a lot less efficient. I would replace the plugs at 60k miles to be safe.

[skeeter55]

I just bought a new 2011, and had a 2001 GMC. Pulled the plugs at 30,000 miles, they looked okay, and re-installed them with anti-seize compound.

 

You can do what you want, but I will keep using anti-seize. This stuff works.

 

 

[RockySierra]

Sorry all, I failed to mention that the issue with the plugs being "welded" in were occurring more on the aluminum headed engines, not the cast iron.

[jefffoxsr]

The dealer wants $500 to replace plugs and wires. So I will do it myself. What is the proper setting for the spark plug gap? I am getting ac delco iridium plugs and ac delco wires.

 

Are the AC Delco wires from the auto parts store the same or same quality os OEM?

 

Thanks.

[Black02Silverado]

Also, using anti-seize is a big, no no. Causes more problems.

 

 

What was the problem caused by anti-seize? Is there a recommended product for the thread, or should the next set of plugs be installed without anythread compound?

 

 

 

Interesting, changed mine out and used anti-seize and didn't have any issues. I was always told to use it when two different metals meet like steel plugs inside an aluminum head. Dissimilar metal corrosion will occur and the anti-seize prevents this from happening.

 

I guess will find out in another 40k miles if it caused problems.

[hrspwr]

The dealer wants $500 to replace plugs and wires. So I will do it myself. What is the proper setting for the spark plug gap? I am getting ac delco iridium plugs and ac delco wires.

 

Are the AC Delco wires from the auto parts store the same or same quality os OEM?

 

Thanks.

 

The factory plugs will come gap'ed, dont touch them. You run the risk of ruining the electrode.

Everyone has their own preference, whether it be performance wires or OEM. I have found that the stuff you get from an auto parts store is not as good as the OEM stuff, when it comes to wires. Just my $0.02. For a stock unmodified truck I would put in AC Delco's....I know I am on the weekend.

[clemsonblozz]

Running a plug that is worn just puts more heat and strain on your coil packs.. they have to produce more umph to cross the larger gap, thus more heat.

[shawnastleford]

I wouldn't waste my money on AC plugs. Just buy NGK they are half the price and the AC Delco plugs may be made my NGK. Some Delco plugs are made by NGk, Champion or even Autolight. You can tell by looking at the plugs. Autolight plugs are welded together and you can tell by the blue color just above the seat. NGK stamps their part number into every plug they make right above the seat. Some Delco plug numbers are made by both so it is possible to have 4 Champion and 4 Autolight plugs in your truck but have the same Delco part numbers.

[dsr611]

Changed the plugs on my wife's 05 Tahoe last December at about 105k miles. I had no issues getting them out, other than the normal cutting of the hands/arms, busted knuckles, etc. I didn't use the AC Delco OEM plugs, but instead, bought the Bosch plugs as no one in town had the AC Delco plugs (bought them on a Sunday, spur of the moment purchase...dealer wasn't open and we were leaving on vacation 2 days later). With that said, I haven't noticed any mileage difference between the 2 plugs. And, I did use anti-sieze on the new plugs. Coming from a millwright background, I believe in using it on anything that you don't want to gall up, especially 2 dissimilar metals. No need to coat the whole threaded area...just a little "dab" on the threads will work