Valve cover bolt almost terminal error

Started getting loose at about 4 pounds. Took it out to find it was in process of breaking. There was a ton of rtv under the cover so it must have been over torqued by previous owner. New ones will be about a week to get here. Not ideal but could have been a whole lot worse.

 

I am always concerned about the case threads pulling out before a bolt would ever get close to doing that......

 

Threads in the soft aluminum will go before bolts. I had to put a heli-coil in my 83 head, not hard.

 

I've mucked up more than a couple crank case halves on my 26cc's before and have a variety of heli-coils on hand. Strangely though that was not an issue. I am with the general consensus that the aluminum should have stripped out before the bolt snapped.

Visual inspection of the head threads showed no signs of stripping or cross threading; they looked perfect. Checked all other bolts holes too because it is unlikely the broken one originally came from that spot. Every one looked mint. I put one of the bolts from the other side in place of the broken one and torqued it down with no problem. Maybe it was a faulty bolt? If it was closer to the top where the relief is NOT cut into the threads I could say poor machining but it is right in the middle of the threads, just above where they engage the head.

I thought it was strange and I am glad to not have a bunch of vets jump in to say it is a common issue.

And for whatever it is worth: ordered the parts from local shop and saved 9% on exchange and duty from partzilla.

 

Glad you didn't have that sickening feeling when the aluminum gives out!

 

That is a proper discription when that happens. Usually followed by a lot of 4 lettered words.