Broken spark plugs
Thread Starter
Burning Brakes
Joined: Nov 2013
Posts: 1,036
Likes: 119
Broken spark plugs
Here's a new one for me. I was removing the spark plugs today to check them since I've been getting a slight miss on acceleration. Anyway, I actually broke the ceramic part that the plug wires go onto on 3 of the 4 plugs. On one of them, I broke the whole thing clean off. Luckily the hex part was still left in the head so I could remove it.
I'm using a properly sized magnetic spark plug socket, and these are NGK plugs. I've done plenty of plug changes on other vehicles with no issues, what gives?
I'm using a properly sized magnetic spark plug socket, and these are NGK plugs. I've done plenty of plug changes on other vehicles with no issues, what gives?
Drifting
Joined: Nov 2009
Posts: 1,659
Likes: 8
Normally a spark plug socket has a hollow roll of rubber inside to protect the ceramic. You are getting the shaft and wrench out of alignment with the spark plug and the side load is breaking off the plug. It doesn't take much, even the rebound of when you break the plug loose is enough to do it.
Thread Starter
Burning Brakes
Joined: Nov 2013
Posts: 1,036
Likes: 119
Engine was cold. Side load sounds about right. Access was kind of tight, so I was doing the best I could to not be pushing at odd angles. This may be the first time I've used this particular socket, I'm not sure. My old one had the rubber insert but this one is magnetic and doesn't. After calling up my friend for an emergency ride to the parts store, I installed the new plugs with my old spark plug socket with the rubber insert.
That being said, the gaps on all the plugs looked fine .035, and the plugs themselves looked great. The wires are MSD and seem pretty new.
That being said, the gaps on all the plugs looked fine .035, and the plugs themselves looked great. The wires are MSD and seem pretty new.
Safety Car
Joined: Mar 2015
Posts: 3,637
Likes: 245
Here's a new one for me. I was removing the spark plugs today to check them since I've been getting a slight miss on acceleration. Anyway, I actually broke the ceramic part that the plug wires go onto on 3 of the 4 plugs. On one of them, I broke the whole thing clean off. Luckily the hex part was still left in the head so I could remove it.
I'm using a properly sized magnetic spark plug socket, and these are NGK plugs. I've done plenty of plug changes on other vehicles with no issues, what gives?
I'm using a properly sized magnetic spark plug socket, and these are NGK plugs. I've done plenty of plug changes on other vehicles with no issues, what gives?
Thread Starter
Burning Brakes
Joined: Nov 2013
Posts: 1,036
Likes: 119
I will say it's been a while since I've done a plug change on a pushrod engine. I guess I got spoiled with the OHC engines having the plugs right on top of the valve covers. Though it definitely wasn't as bad as the Subaru I had previously. There was about 1.75" of clearance between the valve cover and the frame.
The car seems to be running a bit smoother, but there's still a some occasional hesitation around 2500rpm.
The car seems to be running a bit smoother, but there's still a some occasional hesitation around 2500rpm.
Thread Starter
Burning Brakes
Joined: Nov 2013
Posts: 1,036
Likes: 119
The first one I broke, I snapped the entire end off. There was about a solid minute of blind panic where I thought I had broken it with just the threads still left in the head. You can imagine my relief when I finally collected myself enough to reach down and feel the hex part of the plug was still there. haha
Last edited by jrp1588; Jul 31, 2017 at 03:17 PM.
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Drifting
Joined: Nov 2009
Posts: 1,659
Likes: 8
The first one I broke, I snapped the entire end off. There was about a solid minute of blind panic where I thought I had broken it with just the threads still left in the head. You can imagine my relief when I finally collected myself enough to reach down and feel the hex part of the pug was still there. haha
I did that on my late model during warmups, with no spare in the right heat range available. I slid the top back down the wire and taped it down with duct tape. Finished the night with no problems!
Race Director
Joined: Aug 2001
Posts: 18,236
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From: Haymarket VA
St. Jude Donor '05-'06-'07-'08-'09-'10
The first one I broke, I snapped the entire end off. There was about a solid minute of blind panic where I thought I had broken it with just the threads still left in the head. You can imagine my relief when I finally collected myself enough to reach down and feel the hex part of the plug was still there. haha
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
When I change plugs, I use a quality plug socket with a padded insulator inside and I also employ a wobble extension, a universal extension and I have a 1/2" long extension that helps get the short snap on socket into tight spaces.
Sometimes, you can use very LONG extensions and get the plug socket on the plug and the ratchet away from interference and get the proper straight shot on the plug.
If you have to apply side loading on the socket, you are most likely going to break the plugs.
Bill
Sometimes, you can use very LONG extensions and get the plug socket on the plug and the ratchet away from interference and get the proper straight shot on the plug.
If you have to apply side loading on the socket, you are most likely going to break the plugs.
Bill
Thread Starter
Burning Brakes
Joined: Nov 2013
Posts: 1,036
Likes: 119
Oh well, at least at 11lbft, I'm not likely to break them going in. I put iridums in there, so I should be good to go for a while. Do these cars usually throw a code if they are missing? I'm just getting a bit of hesitation when I accelerate moderately hard, but it's not throwing any engine codes. It actually seems to pull smoothly if I really step on it, or short shift.
When it gets around 2500rpm there it feels like there's a split second of hesitation, then it's right back on the power.
When it gets around 2500rpm there it feels like there's a split second of hesitation, then it's right back on the power.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
The PCM can detect misfires and will give you a RANDOM MISFIRE DTC--- P0300 if a cylinder/s misfires more than a specific numbers of misfires.
Some scanners and tuning software and pin point what cylinder is misfiring.
Did you change the wires??
What gap did you set the plugs at?
BC
Some scanners and tuning software and pin point what cylinder is misfiring.
Did you change the wires??
What gap did you set the plugs at?
BC
Thread Starter
Burning Brakes
Joined: Nov 2013
Posts: 1,036
Likes: 119
I didn't change the wires since they looked pretty new. I just bought the car a couple months ago. They're MSD wires. I left the plugs at the stock .04 gap which I confirmed with my wire gapping tool.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
I recommend checking the resistance reading on each wire end to end. If you have a HIGH resistance reading, that wire is BAD. Also check the boots and wire insulation for damage. MSD boots are very soft and tear very easily!