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New Spark Plugs


JasonA

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Okay, I finally broke down and bought a new set of spark plugs today. I should let the originals go for another month just to give them a full 150,000 miles of use, but they'll fall just short at about 149,200, as I plan to change them tomorrow.

I figured they (ACDelco 41-950s of course) would be pre-gapped, but not so apparently. It says gap to spec on the box. No problem, got it covered.

I remember bbob saying the original spark plugs had an anti-seize compound in the threads, making extra goop extraneous. Does the same hold true for these service plugs? Should I add a spot of anti-seize to these or not? I expect these to probably last the rest of the life of the car, but I'd still like to be able to remove them in the future, to maybe install new ones 10 years from now if I get itchy that no other issues have arisen by then. :)

I've gotta do a little pre-emptive cleaning before removing the old ones. There's about a 1/4 teaspoon of dust/corrosion at the bottom of the plug holes now, and I need to rig an air wand attachment to my 2 hp Craftsman inflator to blow that crap out. I already loosened it up with a small wire...just need to extract it with some air pressure now.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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Okay, I finally broke down and bought a new set of spark plugs today. I should let the originals go for another month just to give them a full 150,000 miles of use, but they'll fall just short at about 149,200, as I plan to change them tomorrow.

I figured they (ACDelco 41-950s of course) would be pre-gapped, but not so apparently. It says gap to spec on the box. No problem, got it covered.

I remember bbob saying the original spark plugs had an anti-seize compound in the threads, making extra goop extraneous. Does the same hold true for these service plugs? Should I add a spot of anti-seize to these or not? I expect these to probably last the rest of the life of the car, but I'd still like to be able to remove them in the future, to maybe install new ones 10 years from now if I get itchy that no other issues have arisen by then. :)

I've gotta do a little pre-emptive cleaning before removing the old ones. There's about a 1/4 teaspoon of dust/corrosion at the bottom of the plug holes now, and I need to rig an air wand attachment to my 2 hp Craftsman inflator to blow that crap out. I already loosened it up with a small wire...just need to extract it with some air pressure now.

I remember bbob saying NEVER to use anti-sieze on the spark plugs as it reduces the torque values enough that you can overtighten them. Also, if you get any on the electrode, it will ruin the plug. Also, the plugs have a zinc plating on the threads to keep them from corroding.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Hooray!!! It's about time Jason :lol: . Good luck and hope all goes well. It should be relatively easy unless the plugs are frozen..... but even then it shouldn't be too bad of a job. I just use my can of compressed air, the one for my computers, when I need to clear the debris field around the plugs. A man of your particular nature should have a can or two around the house I figure. I've never used an anti-seize compound on any plugs on any vehicle but perhaps some do hmmm. My routine is hand tighten until the plug is seated and then 1/8 of a turn with the socket and ratchet. Let us know how you make out.

"Burns" rubber

" I've never considered myself to be all that conservative, but it seems the more liberal some people get the more conservative I become. "

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Also, the plugs have a zinc plating on the threads to keep them from corroding.

Okay, that's what I was asking about. Even the ACDelco service plugs have that zinc plating? Good enough.

kger2, I actually don't keep any compressed air. I used to work on computers for a living (in high school, I was a help desk co-op at a local defense contractor, my first "real" job). But I got so tired of building and fixing computers, I found my personal hobby for them waning. I haven't built a computer in years. I really wouldn't even consider it anymore, I just buy Dells. It was my hobby, but I think I ruined it by actually "working" it.

Every now and again, I think it'd be fun to be a mechanic, even a "light" mechanic like tire installer or brake guy at a Midas. But I always remember how working computers everyday ruined my hobby in them, and I don't want that to happen with cars. I have worked at Advance Auto before, but I guess that wasn't enough for me to "kick the habit", thankfully! :) I still enjoy doing all my own work, but I don't think I'd enjoy (for long anyway) taking money and doing OTHER peoples' work.

Thanks for the tips guys. I have my electric impact gun handy in case these things get hairy. My biggest fear with this car, and always has been, is stripping the plugs removing them. I don't know why...maybe it's because it's the first aluminum-headed vehicle I've owned. I'm sure it'll be cake.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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Jason:

I'll bet you a box of donuts that the plugs you pull out are all missing the platinum pad on the ground electrode. Which means the gap will be something like 0.005" to 0.010" greater than original for that reason alone.

Another box of donuts that you will not notice any significant difference in start-up, smoothness, performance, or fuel economy with new plugs.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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I use a foot long piece of 3/8"(I think thats the size) clear tubing that snuggly fits over the end of the spark plug. The tubing holds the plug and allowes me to get the plug started in the hole so I know its not cross threaded. Once the plug is started OK I pull the tubing off and put the socket on it.

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I use a foot long piece of 3/8"(I think thats the size) clear tubing that snuggly fits over the end of the spark plug. The tubing holds the plug and allowes me to get the plug started in the hole so I know its not cross threaded. Once the plug is started OK I pull the tubing off and put the socket on it.

I use a similar method to Bill's, only use a pencil with a short piece of the tubing on one end.

You have a little more control of the plug.

Also, all the pads were missing from the ground electrodes on my original plugs.

Barry

2008 STS V8
2016 Colorado Z71
1970 Corvette LT-1 Coupe

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The tubing is a great idea Bill. Ranks right up there with the weed whacker line for clearing clogged sunroof drain lines. I saw some at Ace and Home Depot that should do the trick. I'll have to keep that in mind for the next time.

"Burns" rubber

" I've never considered myself to be all that conservative, but it seems the more liberal some people get the more conservative I become. "

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Also, the plugs have a zinc plating on the threads to keep them from corroding.

Okay, that's what I was asking about. Even the ACDelco service plugs have that zinc plating? Good enough.

kger2, I actually don't keep any compressed air. I used to work on computers for a living (in high school, I was a help desk co-op at a local defense contractor, my first "real" job). But I got so tired of building and fixing computers, I found my personal hobby for them waning. I haven't built a computer in years. I really wouldn't even consider it anymore, I just buy Dells. It was my hobby, but I think I ruined it by actually "working" it.

Every now and again, I think it'd be fun to be a mechanic, even a "light" mechanic like tire installer or brake guy at a Midas. But I always remember how working computers everyday ruined my hobby in them, and I don't want that to happen with cars. I have worked at Advance Auto before, but I guess that wasn't enough for me to "kick the habit", thankfully! :) I still enjoy doing all my own work, but I don't think I'd enjoy (for long anyway) taking money and doing OTHER peoples' work.

Thanks for the tips guys. I have my electric impact gun handy in case these things get hairy. My biggest fear with this car, and always has been, is stripping the plugs removing them. I don't know why...maybe it's because it's the first aluminum-headed vehicle I've owned. I'm sure it'll be cake.

Use the electric impact gun to break loose the old plugs. You won't need to worry about damaging the threads with the impact as it will hammer/vibrate them loose. When my '96 began running rough a year and a half ago, I was worried about damaging the threads removing the plugs - that's why I used the impact wrench. I had the plugs changed out in 30 minutes.

Save some of the old plugs to make them into air adapters to test the head gaskets. ;)

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Hmm...can't even get them out with my electric impact gun. :( I tried two front plugs, and neither even thought about coming out. Of course, I only left the gun on for 5 second "bursts". Do I just need to let the gun wail on them until they give in?

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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Jim, thanks for your quick reply. I couldn't get back on here fast enough to say I figured it out. I just let my electric impact gun wail on them for 10 seconds at a time. A few reps and they're out.

I have the front bank out so far. By the looks of these, I could let 'em go another 100k. :) I'll take a picture.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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Glad you got them out - I would have posted earlier but I was outside washing the cars - It's been 40 degrees for almost three weeks in Michigan and my snowmobiles sit on the trailer. :angry:

You could just check the gap on the old plugs and reinstall them - if they made it to almost 150K and still have the platinum pad on the ground electrode, they'll probably last forever. When my '96 began to run rough on light acceleration, it was due to the plugs - 4 of the 8 plugs were missing the platinum pad. I probably should have replaced the ones that were bad but I installed 8 new plugs.

Replacing the plugs on the Northstar is a piece of cake compared to my Fleetwood with the LT1 engine...

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Kevin, I probably should have just regapped them and put 'em in...

After I got the front four out, I started on the back. I removed the strut tower brace and the ignition module/coil pack assembly. Couldn't get a dang one out in the back row. I couldn't go in straight with the impact gun, so I was using a u-joint. I pretty much tore my u-joint up in the process. The only other option was a breaker bar, but I didn't like that idea.

So I figured I'd just button it back up and go with at least four new plugs on the front row. Not so easy -- there's a miss somewhere. After re-checking all the plug wire connections and routing, I figure I must have broken a plug wire or something. There's a definite miss -- even at idle. The car stumbles at idle when loaded with the transmission in gear. I could drive it, but there's definitely a major miss.

I went ahead and put the old plugs back in the front, but that didn't do anything for the miss. I have some more house chores this afternoon, so I won't be able to get back to the car until after work tomorrow (I'll have to drive the van to work).

But what next? I plan to check the resistance of each wire, to see if I can easily spot the problem. Either way, these wires (Autolite Professional) have a lifetime warranty, so whether or not I find one with too much resistance, I think I'll turn them back in for a new set. I'm not sure what else it could be. I hope I didn't somehow damage the ignition module or a coil...or killed a rear plug trying to remove it.

Any other ideas?

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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Kevin, I probably should have just regapped them and put 'em in...

After I got the front four out, I started on the back. I removed the strut tower brace and the ignition module/coil pack assembly. Couldn't get a dang one out in the back row. I couldn't go in straight with the impact gun, so I was using a u-joint. I pretty much tore my u-joint up in the process. The only other option was a breaker bar, but I didn't like that idea.

So I figured I'd just button it back up and go with at least four new plugs on the front row. Not so easy -- there's a miss somewhere. After re-checking all the plug wire connections and routing, I figure I must have broken a plug wire or something. There's a definite miss -- even at idle. The car stumbles at idle when loaded with the transmission in gear. I could drive it, but there's definitely a major miss.

I went ahead and put the old plugs back in the front, but that didn't do anything for the miss. I have some more house chores this afternoon, so I won't be able to get back to the car until after work tomorrow (I'll have to drive the van to work).

But what next? I plan to check the resistance of each wire, to see if I can easily spot the problem. Either way, these wires (Autolite Professional) have a lifetime warranty, so whether or not I find one with too much resistance, I think I'll turn them back in for a new set. I'm not sure what else it could be. I hope I didn't somehow damage the ignition module or a coil...or killed a rear plug trying to remove it.

Any other ideas? The first thing I would do is order a set of Delco wires, then when they come in go back and put new plugs in, use a good breaker bar on the back plugs, put the new wires on and call it a day.

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Kevin, I probably should have just regapped them and put 'em in...

After I got the front four out, I started on the back. I removed the strut tower brace and the ignition module/coil pack assembly. Couldn't get a dang one out in the back row. I couldn't go in straight with the impact gun, so I was using a u-joint. I pretty much tore my u-joint up in the process. The only other option was a breaker bar, but I didn't like that idea.

So I figured I'd just button it back up and go with at least four new plugs on the front row. Not so easy -- there's a miss somewhere. After re-checking all the plug wire connections and routing, I figure I must have broken a plug wire or something. There's a definite miss -- even at idle. The car stumbles at idle when loaded with the transmission in gear. I could drive it, but there's definitely a major miss.

I went ahead and put the old plugs back in the front, but that didn't do anything for the miss. I have some more house chores this afternoon, so I won't be able to get back to the car until after work tomorrow (I'll have to drive the van to work).

But what next? I plan to check the resistance of each wire, to see if I can easily spot the problem. Either way, these wires (Autolite Professional) have a lifetime warranty, so whether or not I find one with too much resistance, I think I'll turn them back in for a new set. I'm not sure what else it could be. I hope I didn't somehow damage the ignition module or a coil...or killed a rear plug trying to remove it.

Any other ideas?

Jason,

I think I used a 6" extension when I removed the back plugs. I don't recall if I had to use a u-joint but maybe I did - they came right out. I use u-joints frequently with the impact and they hold up fine - I always cup my hand around them though. Is yours a Craftsman? If so, get a new u-joint under warranty. I didn't remove the coil pack when I replaced my plugs.

Hopefully, you did not use anti-sieze on the plug threads... If not, then you probably have a damaged plug wire or a wire that is not fully seated on the plug cap.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Yes here's an idea. If you don't want to remove the rear plugs for whatever reason then take it to a garage and have them pull them. I'd bet a box of donuts that it's one of the rear plugs. I wouldn't think twice about putting a breaker bar on and just get it done. But that's just me and I don't fear the plug. They're a whole lot tougher then people give them credit for. You're searching for a miss that most likely points to a plug since you've pretty much eliminated everything else. If you're afraid to apply the necessary force to remove the plugs then let someone else do it and eliminate the rear plugs once and for all. They're not that big of a deal. And like Kevin, I only needed a 6" extension and nothing had to be removed or moved aside. I laid across the engine because I'm not tall enough to get at the plugs from the side.

"Burns" rubber

" I've never considered myself to be all that conservative, but it seems the more liberal some people get the more conservative I become. "

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Thanks guys. I'm not worried about the plugs themselves breaking -- I'm worried about stripping the threads in the cylinder head. Then I'd have a REAL mess on my hands. I don't have the time nor the cash for that kind of repair right now.

I was thinking about it tonight, and I have a timing light, with the inductor lead. In theory, I should be able to use that timing light to isolate which cylinder isn't firing right? If the timing light lights, there's current through that wire. If it doesn't light, then that's got to be the cylinder that's off.

Interesting, I have the opposite "miss" symptom this time vs. last time. Last time, after they put a new fuel rail on it, the engine would only miss at 1/2 throttle or more. Else, it was fine. This time, if I rev the engine up, it seems to smooth out. I didn't take it on a drive or anything, so I don't know how it'd do under the load of the vehicle, but at idle, there's a definite miss...you can hear it as well as feel it. But rev it up to 2000 rpm, and it smoothes right out. Huh!

I'd gladly take a large cheater bar to those rear plugs if I knew I wouldn't strip the threads. Boy would I feel sorry if I did though...especially after KNOWING the original plugs were just fine. The front four WERE missing their platium pads on the ground electrode, by the way. But the center electrodes weren't excessively worn, and the plugs altogether looked great.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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The plugs needed to be replaced given your description of the miss. It is exactly the same as when my '96 needed plugs - on light acceleration, it would miss and stumble. The fact that the platinum pads on the ground electrodes are missing indicates the plugs were due for replacement.

You need to get the back 4 plugs out and replace them. If the miss is still there, then the wires are probably compromised.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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....

I was thinking about it tonight, and I have a timing light, with the inductor lead. In theory, I should be able to use that timing light to isolate which cylinder isn't firing right? If the timing light lights, there's current through that wire. If it doesn't light, then that's got to be the cylinder that's off.

....

Your inductive pickup timing light will tell you which plug is not firing ONLY IF the problem is the wire. If the problem is NOT the wire, your timing light will be flashing as expected.

I have a full set of wires that I pulled off my engine. If you determine that one of your wires is the problem, I will glady mail one of mine to you so you can avoid buying a complete set. They are basically two different lengths so cylinder #'s are not critical.

Bite the bullet! Go ahead and use a long breaker bar and snap those rear plugs out of there.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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I'm pretty sure the miss is due to the wires. As of 8 hours ago, before I touched anything, the car ran beautifully. Not a single sag, hesitation, miss, or hard start. Not until today when I started messing with everything did things go south. I've always lived by the "don't fix it unless it's broke" mantra, but broke from it when I decided to replace the plugs. Good maintenance, sure, but it's costing me much more than just the cost of the plugs...time and stress (it really frustrates me when the car is not running right).

I suppose the miss could be one of the rear plugs, but it'd be a pretty big coincidence for one to happen to fail the day I changed the front ones out. You don't suppose I damaged one of the coils...by running one side of it with a new plug and one side with an old plug? At this point, I don't even know which cylinder(s) is/are not functioning. If both cylinders on the same coil are out, I'll suspect that first. I didn't treat these wires THAT badly today -- I'd hate to think they're that fragile. What I don't like about these long plug boots is you can't ensure, by feel, that they're all snapped good to the plugs. I can feel and hear the click on the coil side, but those long plug extensions on the cylinder head side make it hard to even know if the wire is on there good.

But I'll be able to know more after testing it one cylinder at a time. All my tools are Craftsman...I may go and exchange that u-joint out. I may also pickup an impact joint (looks more like a CV joint if I recall correctly) and try the rear plugs again, maybe next weekend if new wires do the trick for now.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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....

After I got the front four out, I started on the back. I removed the strut tower brace and the ignition module/coil pack assembly. Couldn't get a dang one out in the back row. I couldn't go in straight with the impact gun, so I was using a u-joint. I pretty much tore my u-joint up in the process. The only other option was a breaker bar, but I didn't like that idea.

....

Seems to me if you tore up a u-joint, you could have also (easily) broken a spark plug insulator.

Stay with it, Jason.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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Jason,

I had good luck loosening spark plugs with the engine warm. Let the engine warm up, then try again. When they break loose, use a little penetrating oil and remove them carefully. If they don't move easily, work them in and out carefully as described previously.

Let the engine cool down before you insert and tighten the new plugs.

Good luck!

Stefan

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Jason,

If you recall, I developed a misfire shortly after the fuel rail recall was done, and I had half the milage that you do. I would almost put money on the wires. Add to that, some of the platinum tips missing which will increase the plug gap to .060 and you have a bonafide misfire. I am sure once you get those plugs and wires changed out she'll be purring like a kitten.

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Thanks for the further replies. I've pretty much psyched myself up to going to Sears and getting a universal joint for impact guns (very similar to what you see here: http://www.mytoolstore.com/sk/sk03100.html). I've always heard that standard u-joints don't stand up well to impact guns, and mine didn't either. I should have clarified that I didn't physically break it, but the u-joint now is hard to flex -- like I ruined the "bearing surfaces" inside it).

I still plan to try to isolate what cylinder is off by running the engine and using a timing light. That'll also get the engine somewhat warm before I try the rear plugs again. If all else fails, I may take it somewhere and have them change out the rear plugs for me.

Larry, I had the same after-recall miss that you did, and have replaced the wires...they're only a year old. But they're Autolite Professionals vs. ACDelco. I may be learning my only-buy-ACDelco-parts lesson as we speak. :)

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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