View Full Version : HELP! stripped spark plug
Sablea4
03-09-2007, 02:22 PM
well i went about changing the plugs for the first time since i bought the car and the two center ones are stuck in there really good. i was able to get one of them out and it seems that i stripped it. there was metal in the groves of the plug toward the bottom and i cant get the new one to get tight. any help would be awesome
What you can do is get a spark plug thread chaser and it should clean up any threads that aren't true. Now, if it's worse, then you'll have to get some heli-coils which will require you to drill it out larger, tap the hole, then screw in the heli-coil which is new threads for the spark plugs. Of course this will leave metal shavings in your cylinder hole ....not good.
Sablea4
03-09-2007, 02:55 PM
is that my only option. called the dealer and 4k to replace cylinder head. said i could do a hot coil or retap threads. im looking into the retap at the moment. i just dont see how something as easy as changing your plugs could go so bad.
said i could do a hot coil or retap threads. im looking into the retap at the moment. i just dont see how something as easy as changing your plugs could go so bad.
That's what a heli-coil is, or hot coil...replacement threads. Something as easy as changing plugs can go this wrong if the engine was not cool enough OR anti-seize compound was not added to the threads from the first time. Your best bet is to change your plugs before you run your car for the first time that day. This way, you know for sure the engine has cooled sufficiently from the day/night before.
F16HTON
03-09-2007, 03:36 PM
Any competent machine shop can do a heli-coil without gettting shavings in the cylinder
Sablea4
03-09-2007, 03:36 PM
ok....should i bribe a mechanic to come do it at my place or take the head off or flatbed the car?
Any competent machine shop can do a heli-coil without gettting shavings in the cylinder
Ok, I may not know the procedure you're talking about, but if you put in a HeliCoil like the ones I use in (HeliCoil brand from their master kit), you are going to get metal shavings in the cylinder if you do it while the head is still attached.
What part of drilling into the sparkplug thread hole isn't going to push shavings into the cylinder? And if that doesn't do it, the tapping of the new hole to accept the HeliCoil will.
Now, you may know of some sort of special technique (no, a grease covered drill bit won't work) that I don't. If you do, please enlighten me (that wasn't written to be a smarta$$... or maybe it was).
My only guess would be a super strong magnet (that attracts aluminum magically) or something of the sort.
You can always vacuum it out, but I wouldn't trust that method on a cylinder.
This also stands a chance of happening if you chase the thread.
I have a few questions Sable. Are you 100% positive that it was metal on the threads? I know it sounds dumb, but sometimes anti-seize dries up really hard and looks like aluminum.
Did you install the new plugs with anti-seize (please say yes)?
In your defense, you are probably not the one who stripped them. The blame lies with the person (or machine) that put the last set of plugs in.
OldManTan
03-10-2007, 05:35 AM
There are techniques that can be used to minimize the metal that ends up in the cylinder... but no way to guarantee or completely prevent them. The good news is that they are aluminum so they are pretty soft.
If it was my car, I would pull the head and have it heli-coiled.
If you don't have the time and/or mechanical skill, and you have limited budget - have someone pull the turbo and re-thread it on the car. Make sure the intake valves for that cylinder are closed and blow out the shavings with compressed air.
Any competent machine shop can do a heli-coil without gettting shavings in the cylinder
Would love for you to explain this magic. Out of all the motors I've built and spark plug holes stripped from previous installers, I have never been able to retap the hole without getting metal shavings in the cylinder bore. In other words, it is impossible.
Papachristou
03-10-2007, 06:19 AM
im sure there is some kind of technique for it because no telling how many people do it every year lol!
old guy
03-10-2007, 06:28 AM
Here is an article I found on repairing stripped spark plug holes. It may be of interest.
http://www.popularmechanics.com/automotive/how_to/4212608.html
The article has the techinques I use but you won't be able to get all the chips out. However, you can get out enough to where it won't harm the engine which is the only thing that matters.
A cylinder head with stripped sparkplug threads is basically "trash" in my books. Helicoils and other thread repair kits can only do so much and is merely a band-aid. In a race application where plugs are often changed, and heat (high/low) heat cycling occurs, those threads will easily bulge. Also...if your head is that old where it stripped like that, time for a rebuild anyways.
BarryT82
03-10-2007, 09:01 AM
I used a helicoil on an old car I had. I took a piece of vacuum line and put it on the end of my shopvac hose to suck the shavings out. It worked fine and I never had a problem out of the car again.
F16HTON
03-10-2007, 09:36 AM
Machine shops repir heads all of the time. You rotate the crankshaft until the cylincer is at TDC, then they insert a medium into the spark plug hole to prevent shavings from going into the cylinder (they are many ways...rope is often used.
As they cut the threads for the insert, oil is used which keeps the shavings to a minimum. The spark plug hole is then thouroughly cleaned, vaccuumed and blown out. Because the entire cylinder has been blocked off you will not get any shavings in it.
Here is a DIY if you want one http://www.automedia.com/Spark/Plug/Hole/Thread/Repair/ccr20020401st/1
Sablea4
03-10-2007, 10:46 AM
so it sounds like i need to remove the head unless im getting it flat bedded.
Sablea4
03-10-2007, 10:52 AM
I have a few questions Sable. Are you 100% positive that it was metal on the threads? I know it sounds dumb, but sometimes anti-seize dries up really hard and looks like aluminum.
Did you install the new plugs with anti-seize (please say yes)?
In your defense, you are probably not the one who stripped them. The blame lies with the person (or machine) that put the last set of plugs in.
im almost positive. here is a picture
http://img.photobucket.com/albums/v75/Sablea4/IMG_0951.jpg
yes i used anti-seize on the new ones i could get in.
Anti-sieze won't save your aluminum when you over tighten.
quattrotman
03-10-2007, 10:30 PM
Man, I hate to say it but you're hooped. All the things suggested like helicoil could work but chances are it's never going to be the same and may not seal or thread properly. Stripped threads on a spark plug almost always spells E X P E N S I V E. Sorry but I'm sure you'll get lots of advice and 'fixes' but I think you're going to have to bite the bullet and get a new head. On older cars you could sometimes take off the head and thread a slightly larger hole and use a different plug for that one but on today's car's that aint gonna work. Check with a few shops (not dealers) and see what they can do for you but this is probably not your averge DIY job.
dirtyserby
03-11-2007, 09:25 AM
this was always one of my biggest fears...especially when buying a used car...not knowing what the previous owner did
I'm sitting in a similar boat. I tightened up a new set of plugs last night. I could tell when I took out the old ones that they were too tight. I'm just hoping that they can hold out and not give me the dreaded female threads on plugs problem.
diagnosticator
03-12-2007, 05:17 AM
OK, the best thing to do, is pay an experienced tech/machinist, to install a heliCoil or TimeSert insert WITH the head Installed. With the several methods mentioned, aluminum chips falling into the cylinder are minimized. And as a practical matter, a few bits of aluminum in the cylinder, will be blown out the exhaust port almost immediatly at start up, and won't cause any damage. I have done this several times. Removing the head opens other things to go wrong as well as the high cost, and is not needed to fix this problem.