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+--- Thread: Exhaust manifold bolt holes stripped (/showthread.php?tid=10679)
Exhaust manifold bolt holes stripped - Redland1 - Yesterday
I replaced gaskets and bolts on the exhaust manifold a couple of months ago and when I was torquing I the bolts three kept turning. I ended up putting in helicoils. Recently I started to hear a loud exhaust leak and isolated the cylinder from where it was coming from and retorqued the bolts but the lower one just turned endlessly which has a helicoil. I’m thinking of drilling it out to the next size up and using timesert’s on all bolt holes so I don’t have to deal with this again. Will be ordering a new manifold,and gaskets. Will drilling it out to the next si.•ze up and putting in timeserts work ?
Also is there a drill guide or something to get a perfectly straight hole ?
RE: Exhaust manifold bolt holes stripped - Rawze - Yesterday
I have had a TON of experience with heli-coils in my past ...
Personally, I have never seen a proper heli-coil break when done right... not even come close to breaking even when over-torqued, unless it was severe. - Something else is wrong.
Did you use a torque wrench to set them ??.
What torque were you torquing the bolts to?.. and was your torque wrench accurate?.
How deep are the threads that are tearing off?.
What is the width of the bolts (shank diameter in mm) ?.
Are you using OEM bolts, and OEM stand-offs?.
Is it an OEM manifold?, and is that manifold on any TSB list for an upgrade or modification?. One similar to this:? https://rawze.com/forums/showthread.php?tid=7564&pid=66592#pid66592
How deep are they threading into the head (in mm)?
what size heli-coil did you use?, and how deep were its threads (in mm)?.
Possibly bad de-mandate tuning that overheats the exhaust / manifold, or perhaps over-boost the engine like mad?.
Something does not sound right at all there.
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as far as a drill guide, you can get one at amazon, home depot, etc ....
https://amzn.to/4yIq735