# Stripped Bolt Hole in Cylinder Head



## Kimmy (Jun 8, 2011)

Hi all! We have been the proud owners of a 99 Nissan altima for about 6yrs now and it has been a very reliable car...minus the brakes. This is my first post about getting help with repairing her back up so please bare with me :newbie:

The head gasket blew out, we tore her down, got the head out and serviced it. We put it back in last night and in the middle of getting the bolt back in the Crankshaft sprocket (in case that is not its name, here’s a short description...first you have the duel over head cams at the top of your head with its timing chain going down to a sprocket just below them in the middle that bolts to your cylinder head. The one in the middle is what I’m talking about) the treads inside the cylinder head for that sprocket stripped out.
My question is what would be the best way to go about fixing that ourselves? There are a few ways we know of but not sure what would work best for an aluminum cylinder head.

It's a 99 Nissan altima 2.4l Any and all opinions would be much appreciated and a real big help, Thank You, Kimberly


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## jdg (Aug 27, 2009)

Helicoil it...if there's enough "meat" to drill into that particular spot on the head itself.

1 - Drill out the hole to the next larger sized bolt (maybe 2 sizes depending on the original)
2 - Tap the hole to match the threads of the helicoil.
3 - Insert "helicoil".
4 - Put the bolt in.
5 - Profit??? 

And if you stripped out the threads with that old bolt, I'd double-triple check the threads on that bolt. That's usually what happens when you wreck threads in an aluminum 'whatever'...bad threads on the steel bolt tear them up on the way in.


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## Kimmy (Jun 8, 2011)

jdg said:


> Helicoil it


Thank you very much! This is the first time dealing with this type of issue. I saw a few products searching for a fix for this and this was one of the products that came up. I will research the helicoil, learn to do it right and let you know how it goes. Thanks again!:cheers:


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## jdg (Aug 27, 2009)

And holy crap, thanks for not asking "What's a helicoil?"
You wouldn't believe how many times something like that gets asked when a simple google would've answered questions like that in 1/10 of the time...

I don't suppose there's enough room to get a nut on behind where that stripped out hole is?
Or maybe run a tap thru there and pull the threads back up? Aluminum being fairly soft just might do that for ya depending on how wrecked the original threads are.
And I think I'd get a machine shop to do the helicoil, being part of the timing chains and all... Nothing like thinking you got it fixed perfectly good, only to have the damn thing fall out after a couple of months and smack a few valves because you were something like .001" out of alignment or something.


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## CMax03 (Jan 17, 2009)

:showpics:


Kimmy said:


> Hi all! We have been the proud owners of a 99 Nissan altima for about 6yrs now and it has been a very reliable car...minus the brakes. This is my first post about getting help with repairing her back up so please bare with me :newbie:
> 
> The head gasket blew out, we tore her down, got the head out and serviced it. We put it back in last night and in the middle of getting the bolt back in the Crankshaft sprocket (in case that is not its name, here’s a short description...first you have the duel over head cams at the top of your head with its timing chain going down to a sprocket just below them in the middle that bolts to your cylinder head. The one in the middle is what I’m talking about) the treads inside the cylinder head for that sprocket stripped out.
> My question is what would be the best way to go about fixing that ourselves? There are a few ways we know of but not sure what would work best for an aluminum cylinder head.
> ...


:showpics::showpics:


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## smj999smj (Jan 1, 2006)

The "sprocket" you are referrring to is called the main gear, which connects the lower chain to the upper chain. I would suggest removing the head and sending it to a machine shop for evaluation. Perhaps they can chase the threads if they are not too bad. There is an oil channel behind behind the bolt which leads to the upper chain tensioner, so I would be careful about shavings if you attempt to do it yourself. If the threads are badly stripped, the best fix may be to replace the head.


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## Kimmy (Jun 8, 2011)

jdg said:


> And I think I'd get a machine shop to do the helicoil, being part of the timing chains and all... Nothing like thinking you got it fixed perfectly good, only to have the damn thing fall out after a couple of months and smack a few valves because you were something like .001" out of alignment or something.


Thanks for your input on that.:kiss: We took it in and got her done!


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