Helicoil question
Thread Starter
Drifting
Joined: May 2000
Posts: 1,769
Likes: 147
From: Penfield NY
Helicoil question
I messed up and cross threaded a header bolt during my LG installation. Well, actually I did it while changing out the gasket to the correct one later on after the install. All the other bolts lined up fine and were hand tightned in and when I put the last one in I got it cross threaded. Of course it's the back one closest to the firewall on the driver's side. Instead of doing something about it I guess I panicked and tightened it in crooked. I know, I know, I'm an idiot. 
I guess now I have to take it to a shop and have them helocoil it to get it right because I think there might be a small leak there. I can smell exhaust fumes when I'm stopped at a light and I'm pretty sure that there are no other leaks in the rest of the exhaust system. Can this be done with the head still on the engine or will it have to come off? I want to make sure I don't get ripped off for labor time when I get this done. Thanks.
I guess now I have to take it to a shop and have them helocoil it to get it right because I think there might be a small leak there. I can smell exhaust fumes when I'm stopped at a light and I'm pretty sure that there are no other leaks in the rest of the exhaust system. Can this be done with the head still on the engine or will it have to come off? I want to make sure I don't get ripped off for labor time when I get this done. Thanks.
Melting Slicks
Joined: Jan 2002
Posts: 2,754
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From: Nokomis FL
Unprofessional reply from another guy that's screwed up threads before.
Several issues:
1)A helicoil take a larger drilled hole than the standard tapped hole size
2)You need to get a drill in there to open it (angle?)
3) You'll need to tap it(maybe with a wrench?)
4) The helicoil uses a special insert tool that's maybe 12" long(no way)
Your probably going to have to pull the head.
If you do look into what's called a Jergens insert. Stronger.
Several issues:
1)A helicoil take a larger drilled hole than the standard tapped hole size
2)You need to get a drill in there to open it (angle?)
3) You'll need to tap it(maybe with a wrench?)
4) The helicoil uses a special insert tool that's maybe 12" long(no way)
Your probably going to have to pull the head.
If you do look into what's called a Jergens insert. Stronger.
Safety Car
Joined: Jun 2003
Posts: 4,640
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From: Sunshine State
Originally Posted by Old Rotor Head
Unprofessional reply from another guy that's screwed up threads before.
Several issues:
1)A helicoil take a larger drilled hole than the standard tapped hole size
2)You need to get a drill in there to open it (angle?)
3) You'll need to tap it(maybe with a wrench?)
4) The helicoil uses a special insert tool that's maybe 12" long(no way)
Your probably going to have to pull the head.
If you do look into what's called a Jergens insert. Stronger.
Several issues:
1)A helicoil take a larger drilled hole than the standard tapped hole size
2)You need to get a drill in there to open it (angle?)
3) You'll need to tap it(maybe with a wrench?)
4) The helicoil uses a special insert tool that's maybe 12" long(no way)
Your probably going to have to pull the head.
If you do look into what's called a Jergens insert. Stronger.
Thread Starter
Drifting
Joined: May 2000
Posts: 1,769
Likes: 147
From: Penfield NY
It's hard to tell how they would do it IF they can do it with the head on the car. I guess if it's necessary to remove the head I'd rather have it done that way and know that it's fixed for good. Thanks for the responses.
Le Mans Master
Joined: Feb 1999
Posts: 7,121
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From: Vilano Beach FL
Heck, it might not be a bad time to pull *both* heads - send em to a head specialist for the repair and have some port/polish work done! Add some new valvetrain gear, etc.
I always like to look at an "uh oh" as an opportunity to upgrade
I always like to look at an "uh oh" as an opportunity to upgrade
Drifting
Joined: Jun 2004
Posts: 1,887
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From: Havin' fun in Frederick, MD!!!
St. Jude Donor '05 '09
Man that sounds nasty. Make sure you can't recover without all that work. I thought I had buggered one of my front sway bar holes (also in aluminum), but a friend showed me how to spit on the screw and restart it and it went in fine (after carefully restarting it). I'm sure any light lubricant would do it, but you don't want it to unthread itself again later. I would expect because you don't have a good eyeball on how to line up the screw, it's going to be easy to cross-thread and difficult to get it straight.
Team Owner
Joined: Dec 2003
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From: When all is said and done... there is a hell of a lot more said than done. Riverside,Texas
St. Jude Donor '05 thru '26
Originally Posted by vettenuts
Have you tried simply chasing the original threads first? Might want to try that and then a stud to see if it will hold.
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Team Owner
Joined: May 2001
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From: Western NY
What I would try, if just chasing the thread won't work, is this: Get a piece of round steel bar, about 1/2" diameter, 1" long. Turn both ends flat in a lathe, then drill a hole down the middle with the Heli-Coli drill. This will become your "drill guide".
Remove the header, and holding the "guide" TIGHTLY to the head surface, drill out the bolt hole. The "guide" will get you in srtaight, then you can insert a Heli-Coil. I've done this a couple of times for tranny pan bolts.
Remove the header, and holding the "guide" TIGHTLY to the head surface, drill out the bolt hole. The "guide" will get you in srtaight, then you can insert a Heli-Coil. I've done this a couple of times for tranny pan bolts.
Premium Supporting Vendor
Joined: Oct 2001
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From: Dallas Tx
St. Jude Vendor Donor '03-'04-'05-'06-'07-'08-'09-'10-'11
Originally Posted by vettenuts
Have you tried simply chasing the original threads first? Might want to try that and then a stud to see if it will hold.
This would be your best bet. you can locktight the stud in place after you straighten the threads out. should save you the trouble of pulling the head but you will probably have to move the headers out of the way.
Sorry that happened. We usually install the rear header bolt first because it is the hardest to get straight if the other bolts are in. then we use a small punch to line up the other ones prior to tightening them. We always thread them in by hand about 75% of the way to make sure that they are not crossed.
Lou G
Safety Car
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From: Sunshine State
Originally Posted by LG Motorsports
This would be your best bet. you can locktight the stud in place after you straighten the threads out. should save you the trouble of pulling the head but you will probably have to move the headers out of the way.
Sorry that happened. We usually install the rear header bolt first because it is the hardest to get straight if the other bolts are in. then we use a small punch to line up the other ones prior to tightening them. We always thread them in by hand about 75% of the way to make sure that they are not crossed.
Lou G
Sorry that happened. We usually install the rear header bolt first because it is the hardest to get straight if the other bolts are in. then we use a small punch to line up the other ones prior to tightening them. We always thread them in by hand about 75% of the way to make sure that they are not crossed.
Lou G
Thread Starter
Drifting
Joined: May 2000
Posts: 1,769
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From: Penfield NY
Originally Posted by LG Motorsports
This would be your best bet. you can locktight the stud in place after you straighten the threads out. should save you the trouble of pulling the head but you will probably have to move the headers out of the way.
Sorry that happened. We usually install the rear header bolt first because it is the hardest to get straight if the other bolts are in. then we use a small punch to line up the other ones prior to tightening them. We always thread them in by hand about 75% of the way to make sure that they are not crossed.
Lou G
Sorry that happened. We usually install the rear header bolt first because it is the hardest to get straight if the other bolts are in. then we use a small punch to line up the other ones prior to tightening them. We always thread them in by hand about 75% of the way to make sure that they are not crossed.
Lou G
By the way, I was at Mid-Ohio this weekend but didn't get a chance to look you up in the paddock and say hello. Your car looks and sounds great and you drove a heck of a race. Congrats!
Safety Car
Joined: Sep 2003
Posts: 3,558
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From: Cape Coral FL
I did that to myself but on the driver's side and one of the middle bolts. I bought an 8mm helicoil kit with the correct tap and the install tool. The helicoils were about 10mm long and the install tool was about the size of a large key. I didn't have to drill out the hole. All I did was make sure the hole was clean of shavings. Then I ran the tap in, making absolutely sure it was as straight as I could get it. I only went about 1/2 turn at a time. Then when I had the thread about 12mm deep I inserted the helicoil. I purchased an 8x15 or 8x16mm bolt, can't remember the length, and tightend it up. It work great up until I changed my heads 6 months later. You might want to have a machine shop make a small jig to keep the tap square to the hole, considering where it is. A piece of 1/2" aluminum with 2 holes, one to mount it to the next header bolt hole and the other just large enough for the tap should work.
Thread Starter
Drifting
Joined: May 2000
Posts: 1,769
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From: Penfield NY
I appreciate all the suggestions. My fear is that given where it is and how tight that location is that I won't be able to get the tap in straight and end up with a worse mess. I'm NOT the world's great mechanic to start with! I just don't have much confidence in being able to do this and I don't want to screw up the aluminum head any further. I think you guys are a whole lot better at this stuff than I am......
Safety Car
Joined: Sep 2003
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From: Cape Coral FL
Originally Posted by C5LOU
I appreciate all the suggestions. My fear is that given where it is and how tight that location is that I won't be able to get the tap in straight and end up with a worse mess. I'm NOT the world's great mechanic to start with! I just don't have much confidence in being able to do this and I don't want to screw up the aluminum head any further. I think you guys are a whole lot better at this stuff than I am......
Safety Car
Joined: Jun 2003
Posts: 4,640
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From: Sunshine State
Originally Posted by ArKay99
I did that to myself but on the driver's side and one of the middle bolts. I bought an 8mm helicoil kit with the correct tap and the install tool. The helicoils were about 10mm long and the install tool was about the size of a large key. I didn't have to drill out the hole. All I did was make sure the hole was clean of shavings. Then I ran the tap in, making absolutely sure it was as straight as I could get it. I only went about 1/2 turn at a time. Then when I had the thread about 12mm deep I inserted the helicoil. I purchased an 8x15 or 8x16mm bolt, can't remember the length, and tightend it up. It work great up until I changed my heads 6 months later. You might want to have a machine shop make a small jig to keep the tap square to the hole, considering where it is. A piece of 1/2" aluminum with 2 holes, one to mount it to the next header bolt hole and the other just large enough for the tap should work.
Safety Car
Joined: Sep 2003
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From: Cape Coral FL
Originally Posted by Korreck
So you used an undersized bolt to mount the header? Sounds like another good option.
, just length. Long and thin, goes way in, short and fat, they like that.
Safety Car
Joined: Jun 2003
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From: Sunshine State
Originally Posted by ArKay99
It wasn't undersized in terms of girth , just length. Long and thin, goes way in, short and fat, they like that.
, just length. Long and thin, goes way in, short and fat, they like that. 
into an existing diameter hole without enlarging it to accomodate an insert that will accomodate the same size dia bolt?If you understand this you're one hell of a man.
Team Owner
Joined: May 2001
Posts: 87,315
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From: Western NY
Originally Posted by Korreck
How can you insert an insert into an existing diameter hole without enlarging it to accomodate an insert that will accomodate the same size dia bolt?
If you understand this you're one hell of a man.
into an existing diameter hole without enlarging it to accomodate an insert that will accomodate the same size dia bolt?If you understand this you're one hell of a man.
Safety Car
Joined: Sep 2003
Posts: 3,558
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From: Cape Coral FL
Originally Posted by Korreck
How can you insert an insert into an existing diameter hole without enlarging it to accomodate an insert that will accomodate the same size dia bolt?
If you understand this you're one hell of a man.
into an existing diameter hole without enlarging it to accomodate an insert that will accomodate the same size dia bolt?If you understand this you're one hell of a man.
As stated above, the aluminum being soft probably helped this process and the outcome was I didn't have to drill out the hole any larger.