Spark Plug Hole Repair?
 

I've ran into a minor problem. My #2 spark plug hole seems to have stripped threads at the very end of the hole(threads closest to the piston chamber). I maybe have 2 more full turns to go before the spark plug can seat properly, but I am unable to do so because of the stripped threads.

Is there a way to fix the threads without having to go through the whole mess of using an repair kit? Will a tap by itself work and if so what size? And if not, then what tool can I use to just straighten out the threads? It's not that bad, but it's causing a misfire code because I can't seat the plug in all the way.

Re: Spark Plug Hole Repair? (hrdtopv8)
 

Get an old spark plug. Then take a hacksaw and cut about 4 or 5 vertical clean cuts across the threads. This will fashion a makeshift tap.

The only problem I see doing this is make sure no pieces of aluminum get inside the cylinder. :eek:

Re: Spark Plug Hole Repair? (hrdtopv8)
 

There is no way to assure you are not going to get metal in the combustion chamber. I'd be damn sure they really are stripped. Seems like an odd place for them to strip. Do you know how it happened? I'm only curious to get an idea if that is really the case. Spark plugs should be clean and dry when installing, and my memory is that the torque on most engines is no more than 25 lb ft. And do not lube them as this will cause them to over torque too easily.

The best way to MINIMIZE metal shavings from a tap is to load the tap with a heavy grease to hold the shavings to the tap. But how are you really gonna know?

Keep us posted so we can all learn a little (I've got $5 for my part of the education process)

Re: Spark Plug Hole Repair? (jschindler)
 

http://www.corvetteforum.cc/zeroimg/...withstupid.gif

I don't know how in the world the threads could be stripped only at the bottom of the hole, I would first get another plug and try that before tapping it. If the sparkplug feels loose after threading to the point it stops, I would say more than likely, all of the threads are bad. If the top threads aren't holding enough to "force" the sparkplug through the bottom threads, this is the case, and will probably need to be drilled, tapped, and heli-coiled.

Definitely load the tap (or old cut sparkplug) with grease. This will keep any shavings on the tap, and not in the cylinder. THEN, after chasing the threads with a tap (a thread chaser would be a better tool to use), clean the threads with a wooden dowel with a rag wrapped around it, and if possible, rig up a small tube on a shop vac to get into the hole and suck up any possible chips that dropped. I wouldn't recommend using compressed air into the sparkplug hole...if one of the valves are open, you may launch a loose chip up there, and that wouldn't be good either.


Good luck.

:cheers:

Re: Spark Plug Hole Repair? (hrdtopv8)
 

hrdtopv8,

Go to an auto parts store and ask for a spark plug hole "chaser" for your size plug. Probably run you around 5 bucks. They're handy for what you are wanting to do, as well as cleaning the threads of any carbon deposits which ofen accumulate near the bottom of the threads.

I think you'll be fine once you chase the threads. Follow the directions above and slather some grease on it.

Good luck.
Mark

Re: Spark Plug Hole Repair? (MDT)
 

I know for sure it's not stripped to the point where I have to drill and tap. The only way I can describe it is if you look at the old plug you can see that on the second thread (closest to the puck) it is flat and dull NOT a sharp straight line like it is intended to be.. This leads me to believe there is some debris stuck in the threads of the spark plug hole that need to be cleaned out. I have a feeling that this occurred when I used the valve air kit to change out my springs.. :mad

I'll try the chase method with grease and the spark plug method if the first one fails. I let you guys know how it goes. Thanks for all the help..


[Modified by hrdtopv8, 11:00 PM 11/3/2002]

Re: Spark Plug Hole Repair? (hrdtopv8)
 

You can buy spark plug thread chasers that have grooves in them to help keep metal chips from going into the cylinder. I would load it with grease. I also have gone into my motor through the spark plug hole with an articulating boroscope to look around. If you can locate someone who has one, you can check your cylinder after to see if there are any metal pieces. You can get them out with a small rubber tube with a blob of grease on the end or suction, but it takes time and patience and the boroscope. Better then removing the head though. :eek:

Good luck.

Re: Spark Plug Hole Repair? (vettenuts)
 

If the plug chaser/tap fails you can have what they call a helicoil installed in the plug hole. It's a over size metal insert that is installed by a machine shop.

RAY

Re: Spark Plug Hole Repair? (hrdtopv8)
 

I think that a plug may have been started in when it was not exactly lined up correctly (cross threaded). In that case the plug will attempt to go in as you described (it will get harder to thread in as you turn it in.) Finally it will not want to go any more. In this case, you will need an insert for the repair.


[Modified by Supercharged, 1:53 PM 11/4/2002]

Re: Spark Plug Hole Repair? (Supercharged)
 

someone above said to put plugs in dry. NOT ! use anti-sieze

Re: Spark Plug Hole Repair? (hrdtopv8)
 

Did you compare the LENGTH of the plug you took out of that hole to one from another hole? Maybe the last thread seized and when you removed plug it broke or sheard off and is in the hole?
Sounds wild but it may have happened.

Re: Spark Plug Hole Repair? (Stilcrazee)
 

Yep, the length of the plug checks out fine. I bought a chaser and will try it out later this week..

Re: Spark Plug Hole Repair? (aces)
 

Okay, I"ll admit I haven't had auto mechanics in about 33 years, but that's what they taught us then. I just make sure the threads are very clean. You really have to be carefull with anything on the threads that effects you torque, especially with an aluminum block. If I'm wrong, I apologize and stand corrected. :cheers:

Re: Spark Plug Hole Repair? (jschindler)
 

Just did a little research, and the man is correct. Champion's site says to use a little anti-sieze, especially on aluminum engines.

Again, I stand corrected and appreciate the help (damn, you really can teach an old dog new tricks) :D :cheers:

Re: Spark Plug Hole Repair? (hrdtopv8)
 

I ws able to sucessfully use a thread chaser on a Toyota 22re head. It went smoothly. I had crossthreaded the plug. Now everytime I change a plug I always use fingers or a pice of rubber tubing that will just fit over the top tip of the plug to ease them in as far was they will go. And always use a little anti seeze. That 22re was my first experience with an aluminum head. I think you should always change the plugs when the head is cold too. Good Luck!

Re: Spark Plug Hole Repair? (jschindler)
 

jschindler:

just replaced my stock´s with NGK´s. My research said: do not put anything on the thread of the plug. They are already treated with something. Putting copper paste or other stuff on the thread was used in former times.
So I put them in without anything.

Postscriptum:
I did some more research: two guys from the car restoration party say to use copper paste or molybdänsulfid, never normal oil.
One page by BERU, an old german plug producer, says that the thread of their plugs is covered by a nickel layer, so no grease to be used!

So you can find both!
Frederik


[Modified by C5 Frederik, 4:54 PM 11/5/2002]

Re: Spark Plug Hole Repair? (hrdtopv8)
 

Please people use anti-sieze on your spark plugs when installing them in your C-5. This is not specific for c-5s, this should be done on any motor that has aluminum heads. It will save you alot of headache in the long run. :cheers:

Re: Spark Plug Hole Repair? (C5 Frederik)
 

Hey C5 Frederik, thanks for helping to bail me out. :cheers:

I do, however, stand behind my apology as I sometimes :rolleyes: get a little carried away with my responses. I have to learn to not take my self so seriously :smash:

Re: Spark Plug Hole Repair? (jschindler)
 

:cheers: :cheers: :cheers:

Houston................we got no problem

Frederik


[Modified by C5 Frederik, 10:20 AM 11/6/2002]


[Modified by C5 Frederik, 2:24 PM 11/6/2002]

Re: Spark Plug Hole Repair? (C5 Frederik)
 

I changed spark plugs on my daughters cavaliar (4 cyl), removing the original plugs. One was hard to get out and the new plug wouldn't seat all the way, may two rounds short. I thought about most of the options listed on this post, and thought about how could this hole be tapped out without any metal getting into the cylinder and decided to leave it alone. Got it as tight as I could, put the wire on it, closed the hood, and it ran without problems. This could be an option if your gonna sell or trade the car in a few years.

Oh, and if you do this, make sure you don't break the plug accidently when you tighten it up, or your screwed!


[Modified by BLU PIL, 4:07 PM 11/6/2002]