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GMC V6 and V12 Engines Engine repair and rebuilding

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  #1  
Old December 3rd, 2014, 06:30 AM
jagarra jagarra is offline
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Default Stuck spark plug

Ran into an unusual problem. I started working on my 62 GMC with a 305. The PO had pulled 5 of the plugs and stuffed paper in the holes. I stuck some used plugs in there the other day as plugs so I could wash the engine. Yesterday, since the weather was not bad, I decided to run the valves and do compression check. Removed the driver side valve cover, only to find a push rod not engaging the rocker, it was just loose in there. I installed it back into position, figuring I would see what was up when I adjusted the lash.
I then started removing the plugs to spin the engine. Did the left bank OK, started on the right bank until I got to number 4, the plug the PO had never removed. I could see why. It was tight. I could break it loose just barely, to say it was tight coming out is an understatement. I took all my strength to even loosen the plug out of the cylinder, I must have managed a few complete turns until my long ratchet handle started jumping teeth. I then went to a 1/2 ratchet and it too was jumping teeth. At least it sounded like it was.
Right now I have Kroil in the plug valley hoping it will soak into the threads.
I am not sure if it is cross threaded or just rusty.
Today it rained and was lousy outside, maybe tomorrow, I may have to dig out the impact wrench to spin it out. Hope I don't have to pull the head on this one.
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  #2  
Old December 3rd, 2014, 02:57 PM
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FetchMeAPepsi FetchMeAPepsi is offline
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Default Re: Stuck spark plug

Quote:
Originally Posted by jagarra View Post
Ran into an unusual problem. I started working on my 62 GMC with a 305. The PO had pulled 5 of the plugs and stuffed paper in the holes. I stuck some used plugs in there the other day as plugs so I could wash the engine. Yesterday, since the weather was not bad, I decided to run the valves and do compression check. Removed the driver side valve cover, only to find a push rod not engaging the rocker, it was just loose in there. I installed it back into position, figuring I would see what was up when I adjusted the lash.
I then started removing the plugs to spin the engine. Did the left bank OK, started on the right bank until I got to number 4, the plug the PO had never removed. I could see why. It was tight. I could break it loose just barely, to say it was tight coming out is an understatement. I took all my strength to even loosen the plug out of the cylinder, I must have managed a few complete turns until my long ratchet handle started jumping teeth. I then went to a 1/2 ratchet and it too was jumping teeth. At least it sounded like it was.
Right now I have Kroil in the plug valley hoping it will soak into the threads.
I am not sure if it is cross threaded or just rusty.
Today it rained and was lousy outside, maybe tomorrow, I may have to dig out the impact wrench to spin it out. Hope I don't have to pull the head on this one.
I'm always scared of this when I mess with the plugs because they have a little angle on them, but not alot. It sounds like you might need one of those grabbing remover tools kinda like this http://www.amazon.com/Irwin-Industri...t+remover+tool

Make sure you get the right size. You never know, you might find an old lawnmower plug was run in there just to plug the hole.
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  #3  
Old December 3rd, 2014, 05:54 PM
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Andice Andice is offline
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Default Re: Stuck spark plug

Hopefully the penetrating oil will help. Sounds like a good time to chase all of the threads with tap. I hope it all goes well. Can you use slip a length of pipr over the ratchet to get some better leverage?
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Old December 3rd, 2014, 06:40 PM
jagarra jagarra is offline
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Default Re: Stuck spark plug

I do have a thread chaser for plugs. Problem is that as I try to loosen the plug more I hear what sounds like a ratchet slip, like I am putting so much pressure on the tool and it is giving, never had that problem before with Craftsman's tools. Next step will be a breaker bar, which can't slip. When you rock the socket back and forth, it feels like it is a 14mm plug under there, not much slop. All the rest of the holes spun in with no problems.

I am really starting to think that it was cross threaded when inserted and some yahoo seated it with an air tool.

I was looking and I see that Helicoil makes an nice thread repair kit. We shall see what's up soon. Still raining, supposed to clear up a bit tomorrow.
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  #5  
Old December 3rd, 2014, 08:43 PM
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Default Re: Stuck spark plug

Sounds like an air tool will be required to get it out. Let us know how it goes.
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  #6  
Old December 3rd, 2014, 08:46 PM
bigblockv6 bigblockv6 is offline
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Default Re: Stuck spark plug

Quote:
Originally Posted by Andice View Post
Hopefully the penetrating oil will help. Sounds like a good time to chase all of the threads with tap. I hope it all goes well. Can you use slip a length of pipr over the ratchet to get some better leverage?
That too would suggest as well as some heat. Use small propane or map gas torch.
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  #7  
Old December 3rd, 2014, 08:58 PM
jrmunn jrmunn is offline
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Default Re: Stuck spark plug

jagarra,

If what just went by in Davis, CA is headed your way, I would have doubts about dry weather tomorrow.

Many years ago, I started working on cars with a Craftsman 1/2 inch socket set, and can't imagine getting the ratchet to jump teeth. The 3/8 inch Craftsman set is much easier to use and has fewer clearance problems, but doesn't seem nearly as strong. I would be careful about using a 3/8 inch drive impact wrench on this without breaking something.

The 305E (if that is what you have) engine plugs have a tall set of threads, but I have never in over 30 years had a problem getting them out. So your thought about cross threading sounds right if it is the correct plug for the engine. I think this means that you will be cutting new threads into either the plug or the head while it comes out, while messing up the other threads, which will probably make things more difficult as the plug comes out. Have you tried going at it a little at a time by alternating between screwing the plug in and out, while getting it a little farther out with each try?

Once the old plug is out, if you need to touch up the threads in the head, be sure to get the tap started right so that the new plug can seat correctly. And the worst outcome would be to break off a super hard tap in the hole.

Good luck. My experience with these old vehicles is that you will succeed in fixing this problem so that you can move on to the next.

JRMunn
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  #8  
Old December 3rd, 2014, 09:14 PM
Clyde Clyde is offline
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Default Re: Stuck spark plug

The V6 used two different length plugs, if your heads required the short length thread and some one installed the long plugs 3/4" thread length and it did not interfere with the piston, the threads could be filled with carbon, which will make the plug very hard to remove. If the threads get stripped out of the head you can install a heli-coil in that cylinder with out causing any damage.
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  #9  
Old December 3rd, 2014, 10:12 PM
jagarra jagarra is offline
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Default Re: Stuck spark plug

Yes I have been screwing it in and working it out a bit. there were some old plugs laying in the engine compartment, they looking like they were the long style. I used a old set from a Jag engine, they were the same length and the threads were at least clean. The number on the plugs laying in the engine compartment were R43XLS.
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  #10  
Old December 3rd, 2014, 11:31 PM
bigblockv6 bigblockv6 is offline
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Default Re: Stuck spark plug

The R43XLS is basically a replacement plug for the superseded C43N Plug used in 396 V8 engines in the mid 60's, the 62 305D called for a C44S plug(long discontinued). Provided the R43XLS plug has the same reach as the C44S plug it will work though C44S plug is a step hotter. The early 305 V6's had shorter reach plugs so it's critical to use the proper length of spark plug.
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