Heli-coil for stripped valve cover threads?

1985taylor1925

1985taylor1925

Senior Member
Has anyone had to do this?

I have TWO stripped valve cover bolt holes, which I believe was accomplished by the mechanic(s) who worked on the truck before I bought it. I have had a leak since I bought the truck back in 2010, even though the previous owners "certified mechanic" replaced the valve cover gaskets not long before I purchased. Not long ago I went to check the bolts to make sure they were properly tight as I know that can be a simple cause of a leak. I used a torque wrench, and two of bolts turned way too easily, and just kept turning.

Anyway, this is something I have been putting off for way too long. I have used heli-coil once before, on a mountain bike. But valve cover threads will require a little more caution and precision.

Have any of you had to do this, and can you guys offer some advise on how to go about it? Thanks
 
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I don't see why you couldn't do it. You just need to be extra cautious that you don't get any metal shavings into the head(s).
 
JBurt said:
Maybe this is a horrible idea, but could you just retap the holes a size bigger?
Click to expand...

That's what a helicoil or "Fix-a-thread" does. Taps it one size bigger, then inserts a metal coil that shrinks the threads back down to size.

I've used helicoils on the 3.0L engine with great results. Since the valve cover threads are on the outside of the cylinder head, it's perfectly safe to use.
 
gamefreakgc said:
That's what a helicoil or "Fix-a-thread" does. Taps it one size bigger, then inserts a metal coil that shrinks the threads back down to size.

I've used helicoils on the 3.0L engine with great results. Since the valve cover threads are on the outside of the cylinder head, it's perfectly safe to use.
Click to expand...

Yeah and with heli-coil you don't ever have to worry about stripping threads again. At least not with how little torque the valve bolts require. I know when I used it on my mountain bike fork I was able to get the new bolt really tight with no worries.

How long roughly did it take you to do one? I need to figure an estimate for the entire job
 
I understand what helicoils do, but why bother with the extra hassle? Can you just tap it to a bigger size and use a larger bolt, or do you have to use some kind of rethreading tube to keep the same size bolt?

The only thing I could think of is if you didn't want a larger bolt hole in the vc itself. It is pretty thin and weaking it at all could lead to more cracks. I don't know if going one size up would necessitate make the vc bolt hole larger though. Just spitballing.
 
Typically you would like to use the original fastener/s to keep everything the same as far as torques/ fastener heads etc. Could you just use a larger bolt, probably. Should you , probably not. The heli coil/ time sert is actually going to be stronger and still use the original fastener. Especially in this instance since you're working with an aluminum head. The insert is steel, put into a slightly larger 'hole '. I use them all the time on the BMW valve cover bolt holes on the opposed twin engines. In that situation I can drill out and install new time serts once the covers are off in 15-20 mins. This job may require more time depending on the location of the striped threads. It's all about preparation as with anything. Make sure you drill straight !!!! Keep shavings from falling inside head, etc.
 

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1985taylor1925 said:
Yeah and with heli-coil you don't ever have to worry about stripping threads again. At least not with how little torque the valve bolts require. I know when I used it on my mountain bike fork I was able to get the new bolt really tight with no worries.

How long roughly did it take you to do one? I need to figure an estimate for the entire job
Click to expand...

Took me about an hour I guess, but that was in the middle of the night and being extremely careful. I could do it now in much less time. You just screw in the tap by hand once, insert the coil, twist off the end and you are done.
 
Time Serts are a little overkill for valve cover bolts. For fasteners under a lot of stress like head bolts and engine mounts perhaps.
 
Stiles97 said:
Typically you would like to use the original fastener/s to keep everything the same as far as torques/ fastener heads etc. Could you just use a larger bolt, probably. Should you , probably not. The heli coil/ time sert is actually going to be stronger and still use the original fastener. Especially in this instance since you're working with an aluminum head. The insert is steel, put into a slightly larger 'hole '. I use them all the time on the BMW valve cover bolt holes on the opposed twin engines. In that situation I can drill out and install new time serts once the covers are off in 15-20 mins. This job may require more time depending on the location of the striped threads. It's all about preparation as with anything. Make sure you drill straight !!!! Keep shavings from falling inside head, etc.
Click to expand...

Is that the correct size coil do you know?
 
What do you guys think of this guy on toyotanation? He claims ultra black rtv is basically a permanent fix to leaking valve cover gaskets. And that the recommended torque for the bolts is 15.2 to 20.2 ft-lbs!!! What?? How is that possible. He says the 4.3 to 5.2 ft-lbs is wrong? I'm sure I would strip the crap out of all my vc bolts if I tried that

Edit: I should specify that he is talking about a 3rd gen Camry, not a 4runner. But the torque settings are basically identical for our trucks. Has anyone tried rtv in place of the oem gaskets. I don't even see what the advantage would be, unless it just fills in the tiny gaps better


Solving The Valve Cover Gaskets - Permanently - Toyota Nation Forum : Toyota Car and Truck Forums
 
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I've got a half way stripped threads on 1 of the 6 exhaust manifold studs. Not sure how this happened...it was coming out fine, then it got tough, so I backed it in and out a couple times gently before it kept coming out without much force.

Should I try and fix with something like the helicoil, or will I be ok to just get it back on the remaining threads? Maybe not torque it down all the way to spec? Thanks for the help!
 

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