Stripped Valve Cover Bolt

[joebaehr]

Sad day, stripped out lower corner valve bolt on drivers side lower cover. Can this be heli-coiled?

Tried to attach picture, but not sure it is working.

Thanks!

https://drive.google.com/file/d/1gNFUFjDKUxsD8vMOL9jzUq_VX6NcRLqt/view?usp=sharing

[Newsboy]

Did you try running a die over it to re establish the thread?

[bazar01]

Maybe try a longer 6mm Allen cap screw. 5mm longer?

[mikedsilva]

I didn't realise people removed the studs and replaced with bolts.. I guess they look nicer.

But there should be no reason why you cannot helicoil that thread. TAke the cover off, and go for it. 5 minute job seeing as it's already on your engine stand.

[bazar01]

Time-cert is better.

As Mike mentioned, a stud is better as it is fixed and secured to the aluminum threaded hole. Everytime you remove the valve cover, the stud remains and there's no possibility of stripping the threads because you remove the steel hex nut that is mated to the stud.
Bad idea to replace the studs with cap screws.

[TorqueHead]

Originally Posted by bazar01

Time-cert is better.

As Mike mentioned, a stud is better as it is fixed and secured to the aluminum threaded hole. Everytime you remove the valve cover, the stud remains and there's no possibility of stripping the threads because you remove the steel hex nut that is mated to the stud.
Bad idea to replace the studs with cap screws.

Exactly, and also you get the benefit of a steel nut on a steel stud. As opposed to a steel bolt in aluminum threads.

FYI if planning on trying a longer bolt, the rule of thumb to prevent stripping of the aluminum threads is to have thread engagement that is equal to 1.5 times the diameter of the bolt.

So a 6mm bolt needs to have 9 mm of thread engagement if it is in aluminum.
If it is into steel then the rule is 1.0 times the diameter.

[joebaehr]

The engine Early 95 came with bolts not studs and I did get new ones as part of the top-end rebuild. Will try to retap with longer bolt since they are standard size (not always the case on this car, )

Thanks to all for the advice.

[joebaehr]

No was to despondent to do anything yet, :/

[Cobalt]

993 has cap screws 964 uses studs with nuts. It is such a low torque value 9.7 Nm or just slightly more than 7 ft pounds. I have seen people over torque these which causes the leaks we are all trying to avoid. It is critical that you don't over tighten these down crushing the rubber seals and torque equally amongst all nuts or screws to prevent leaks.

[Jeff Alton]

A helicoil will be fine in this low torque application. A timesert requires a larger hole put into the parent material, not an issue in this case either.... Don't waste time with a longer bolt. Fix it right. A few minutes of time.

Cheers

[lrodri64]

I have done a few,
time cert is the way to go.