For the first time in 5 years, i did something terribly wrong (well something really stupid) on my car. I guess a mix of tiredness, cold temperature, and too much beer pushed didnt help me and i over tighten one valve cover bolt..Result; the threading inside the head is almost gone.

To make a quick example here is a schematic drawn by me, with the level talent of a 5yo.;



The valve cover bolt itself is in good shape. The main problem is that the fragile aluminium threading inside the head just tore off. It came out of it looking like a little spring while i tried putting back a bolt without the valve cover, to see whats wrong. So i am left with an almost empty hole (some thread left down there). I can "tighten" that bolt slightly, enough so i cant loosen it up by hand, but it's far away from the specified torque value.. BTW, it's the one on position 3 (or 2, depending on how you feel) in the tightening sequence of the valve cover.

The big problem is i take it off at least 2 times a year when i dont have any problem (maintenance, aka valve adjustment...belts verification, ...) So i am worried it will not hold for long.

What would be my options for repairing this mistake? I cant really use a bigger bolt since it will need to be much larger..? I tought about filling the hole using some (wich one!?!?) product that could become really hard and re-thread.. I feel really lost now.. Anyone has suggestions on how to save the day?!

BTW, replacing the head is out of the question

 

Look into Heli-Coil Screw Thread Inserts. You may be able to find one the proper size for your application.

 

Ghost accord has the right idea. Helicoils or threadcerts are a viable repair for just such a failure; and they are used all the time.
Here's a video on YouTube that shows you how to do the repair:

http://www.youtube.com/watch?v=RFYa6sjhh_E

Helicoils are available online. As an example:

http://shopping.msn.com/specs/heli-c...1-5-metric-kit

and locally as well

P

 

Thanks alot guys, it's really appreciated. I'll look into it!