Help! Crossthread...
Thread Starter
7th Gear
Joined: Sep 2005
Posts: 7
Likes: 0
Help! Crossthread...
I just bought my 92 red vette July 4th.....engine started running funny so I decided I needed to change the wires and plugs...so far so good....got the first 3 out and in with no problem. The 4th one (closest to firewall on passenger side) got cross-threaded and can't get the plug back in.
I tried buying a $6 dollar thread chaser from autozone but I don't have very much room to work and don't know if i'm lined up right or not.....
Also bough a KD back-tap for $50 but the darn thing is too long and I can't get it in the hole.....
I'm a computer nerd type and am really at a loss right now...any suggestions on how I might approach this short of "taking it to the dealer"?
Thanks.
I tried buying a $6 dollar thread chaser from autozone but I don't have very much room to work and don't know if i'm lined up right or not.....
Also bough a KD back-tap for $50 but the darn thing is too long and I can't get it in the hole.....
I'm a computer nerd type and am really at a loss right now...any suggestions on how I might approach this short of "taking it to the dealer"?
Thanks.
Melting Slicks
Joined: Apr 2002
Posts: 2,943
Likes: 0
From: North Aurora Il
I'd try and get a look at the threads to see how far in the fouled thread is. Maybe a digital camera could get a pic.
Get a tap and tap wrench. Take a spark plug to a hardware store and find a nut that fits the threads, then you know what size threads you have. Then find the same sized tap.
With luck you should be able to start the tap in the existing threads. You'll know if you do it right. You'll feel the tap grab on the good threads. When it hits the fouled portion of the threads you'll feel resistance. In about a 1/4 turn or so, the resistance should ease.
Get a tap and tap wrench. Take a spark plug to a hardware store and find a nut that fits the threads, then you know what size threads you have. Then find the same sized tap.
With luck you should be able to start the tap in the existing threads. You'll know if you do it right. You'll feel the tap grab on the good threads. When it hits the fouled portion of the threads you'll feel resistance. In about a 1/4 turn or so, the resistance should ease.
Race Director
Joined: Dec 2004
Posts: 14,997
Likes: 2
When I do any kind of work like this, where something might fall into the cylinder, I turn the engine over until the piston is at the top of it's stroke. Then I stuff a clean rag in through the spark plug hole.
I know there isn't a lot of room to work. You might want to pull the motormount bolts and use a jack to lift on the engine. That might get you a little more room...
I know there isn't a lot of room to work. You might want to pull the motormount bolts and use a jack to lift on the engine. That might get you a little more room...
Instructor
Joined: Sep 2001
Posts: 247
Likes: 0
From: Marcellus New York
While its not that difficult a fix, if you haven't done anything like that before, it might be time to have someone else do the job.
That said, chances are, if the thread is that messed up, you really need to start thinking about heli-coiling the hole. Re-tapping the hole won't put threads back that have been stripped out.
That said, chances are, if the thread is that messed up, you really need to start thinking about heli-coiling the hole. Re-tapping the hole won't put threads back that have been stripped out.
Racer
Joined: Apr 2004
Posts: 482
Likes: 0
From: Wilmington NC
Save yourself a lot of time and hassle and take it to the dealer. Sometimes trying to save money just isn't worth it and usually there will be a mechanic there who has done this more than once.
The end result of failing to fix this right on your next attempt will cost you more than letting the dealer do it.
My dealer isn't cheap, but they have a very experienced vette mechanic. I know not all dealers are the same though.
Good luck
The end result of failing to fix this right on your next attempt will cost you more than letting the dealer do it.
My dealer isn't cheap, but they have a very experienced vette mechanic. I know not all dealers are the same though.
Good luck
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Melting Slicks
Joined: Apr 2002
Posts: 2,943
Likes: 0
From: North Aurora Il
Originally Posted by wht_slvr_86
kwd1 would this method work for a brake caliper too :bb
Team Owner
Joined: Feb 2005
Posts: 20,111
Likes: 1
From: My redneck of the woods louisiana
The problem (big problem) with simply attempting to rethread the spark plug hole is that whatever filings are created during the process will ultimately find their way into the combustion chamber scoring the cylinder wall. I know it is not what you want to hear, but, the safest way to do this would be to pull the head and have the hole retapped at a machine shop.
Thread Starter
7th Gear
Joined: Sep 2005
Posts: 7
Likes: 0
Thanks to all
Got a guy to come out to my home and couldn't do it with the tools he had so he was to come back (he's a hot rod mechanic)...that was 2 weeks ago so I'm now taking my baby to the dealer. Made 2 car payments and don't even get to drive.
Any ideas on what this should cost me? I live in Birmingham, Alabama. I would appreciate local members letting me know where I can find a trustworthy mechanic.
Thanks for all your advice.
Any ideas on what this should cost me? I live in Birmingham, Alabama. I would appreciate local members letting me know where I can find a trustworthy mechanic.
Thanks for all your advice.
Burning Brakes
Joined: Nov 2005
Posts: 908
Likes: 1
From: Colorado Springs Colorado
#8 Spark Plug woes
I'm in nearly the same boat. That !$#@* #8 plug is just about impossible to replace. I spent the entire day yesterday trying to get the threads to catch on the replacement plug with no luck at all. I also tried to get a thread chaser to catch with no luck, and the threads were fine when the old plug came out.
I guess I'll try to get a 14X1.25 tap in the hole today so I can clean the threads and get a feel for the proper angle of approach, but am really afraid of accidentally cutting a cross thread in the process. I've got the wheel well out, and the tire off, so I can see everything, except of course when I squeeze a hand in to try to install the !@#$!* plug, 3 of which I've now dropped and tossed in the trash.
I'm about ready to vent the AC and remove the evaporator to save myself having to remove the head for repair. So far the threads are good, I just can't get them to start.
Tell me there is some simple trick I haven't tried to get this plug in? I've tried using a rubber hose, and a universal coming in from the side, and my fingers, 12 hours wasted on this one plug so far. I'm at my witts end.
I guess I'll try to get a 14X1.25 tap in the hole today so I can clean the threads and get a feel for the proper angle of approach, but am really afraid of accidentally cutting a cross thread in the process. I've got the wheel well out, and the tire off, so I can see everything, except of course when I squeeze a hand in to try to install the !@#$!* plug, 3 of which I've now dropped and tossed in the trash.
I'm about ready to vent the AC and remove the evaporator to save myself having to remove the head for repair. So far the threads are good, I just can't get them to start.
Tell me there is some simple trick I haven't tried to get this plug in? I've tried using a rubber hose, and a universal coming in from the side, and my fingers, 12 hours wasted on this one plug so far. I'm at my witts end.
Originally Posted by mba_mensan
I just bought my 92 red vette July 4th.....engine started running funny so I decided I needed to change the wires and plugs...so far so good....got the first 3 out and in with no problem. The 4th one (closest to firewall on passenger side) got cross-threaded and can't get the plug back in.
I tried buying a $6 dollar thread chaser from autozone but I don't have very much room to work and don't know if i'm lined up right or not.....
Also bough a KD back-tap for $50 but the darn thing is too long and I can't get it in the hole.....
I'm a computer nerd type and am really at a loss right now...any suggestions on how I might approach this short of "taking it to the dealer"?
Thanks.
I tried buying a $6 dollar thread chaser from autozone but I don't have very much room to work and don't know if i'm lined up right or not.....
Also bough a KD back-tap for $50 but the darn thing is too long and I can't get it in the hole.....
I'm a computer nerd type and am really at a loss right now...any suggestions on how I might approach this short of "taking it to the dealer"?
Thanks.
Burning Brakes
Joined: Nov 2005
Posts: 908
Likes: 1
From: Colorado Springs Colorado
AL scoring CI?
Are you sure? Not to challange you, but I just can't see how aluminum filings could score cast iron, the latter being so much harder... Not that I like the idea of having those filings in there, but still, wouldn't they just get blown out once the engine starts?
If I manage to get the hole cleaned out with a tap on mine, I plan on dropping a 1/4 " ID hose into the cylinder an putting the other end on a blow gun. Maybe I'll do the rag thing too.
If I manage to get the hole cleaned out with a tap on mine, I plan on dropping a 1/4 " ID hose into the cylinder an putting the other end on a blow gun. Maybe I'll do the rag thing too.
Originally Posted by wht_slvr_86
The problem (big problem) with simply attempting to rethread the spark plug hole is that whatever filings are created during the process will ultimately find their way into the combustion chamber scoring the cylinder wall. I know it is not what you want to hear, but, the safest way to do this would be to pull the head and have the hole retapped at a machine shop.
Le Mans Master
Joined: May 2000
Posts: 7,033
Likes: 12
Originally Posted by scranage
If I manage to get the hole cleaned out with a tap on mine, I plan on dropping a 1/4 " ID hose into the cylinder an putting the other end on a blow gun.
Burning Brakes
Joined: Nov 2005
Posts: 908
Likes: 1
From: Colorado Springs Colorado
Can't see why it wouldn't work. All that compressed air has only one place to go, and that's exiting the spark plug hole. Why wouldn't it carry any filings left on the bore with it?
Anyway, I also ordered a bore scope so I'll be able to get a good look before I button it up and start the engine.
Anyway, I also ordered a bore scope so I'll be able to get a good look before I button it up and start the engine.
Burning Brakes
Joined: Nov 2005
Posts: 908
Likes: 1
From: Colorado Springs Colorado
The other thing I was thinking about was replacing the injector with a barbed fitting and blowing air into the cylinder while running the tap, only problem is I hate pulling anything fuel related that's pressurized for fear of a leak and engine fire. Is there anything like a cooling system leak tester made for fuel injection systems?
