Valve Cover stud bolt

[disco51]

Went to check my valve clearance after about 1500 miles on the bike for me.  The exhaust valve was pretty closed up last time, hence the early check.
Was suprised to find that the stud bolt (M8x70) and cap nut holding the right sided valve cover in place were no where to be found.  I have no idea where or when it went.  I felt like it might have been stripped last time I checked.  So, I have no idea how long it's been gone.  Bikes been running fine.  If it's stripped, what's the fix?
Thoughts?

[Bob_Roller]

Threaded insert is a usual fix for this, not too uncommon to hear of this .

[Barry]

Bit of a botch but it might be possible drill the stud hole through to the gap in the head and slide a nut down there. The cover can then be secured with a bolt. Not how I'd do it though.


Prevention is better than cure. Reason they fail is because of that gap the thread is not deep enough and worse still the stud is too short and may not be screwed in far enough so will not be using all the available threads in the head.  For anyone who hasn't had theirs fail it might be worth checking how far they are screwed in.  I was able to get a couple of extra turns on mine which can only help (easy does it though).
Of course that means a couple of less threads on the cap nut but it can cope being steel on steel.

[disco51]

Having never done a threaded insert, how difficult is this?  
I'm guessing the appropriate sized Helicoil will work.  Do I need a guide of some sort when drilling in the insert or just line it up with my eyes?

[Bob_Roller]

Needs to be installed straight, if it's at an angle, you may get seepage or leakage from the valve cover gasket  .

[montmil]

Helicoil will do it. You may not even have to drill for the Helicoil -as the aluminum is soft enough and the H'coil insert is close in size. Just run the tap through and then install the threaded insert.

Now that you've been riding around without the stud n' nut, you'll get a better understanding that it's the two small studs n' nuts on the fore and aft that do all the rocker box gasket sealing work.

Be sure to install a new "wavy washer" when fitting that new and pricey dome nut. Snugged up is fine. Do not overtorque... save that muscle for the fork drain screws and the transmission ground strap bolt... and the final drive "level" bolt... and the...  

[disco51]

Yes, very funny...
speaking of that, I guess it's time to try all my helicoil work at once.  Anyone know the size for the fork drain plug - M6 x 1?  I currently have some threadlock and a rubber washer on one side - that's holding, but I've been waiting for that one to bust loose.

[montmil]

M6x6 plus a crush washer.

[Bob_Roller]

The crush washer also needs to fit into the machined area around the hole for the drain bolt .

[Kookaburra]

My 85 R65  had stripped helicoils in both of the stud holes from previous PO.  Used 'keyserts' of the right pitch/diameter to take new studs after drilling and tapping the holes to the right size. It has worked well.

[Tony Smith]

 Do I need a guide of some sort when drilling in the insert or just line it up with my eyes?

Firstly you may not need to drill at all, if you choose to try running the helicoil tap w/o drilling first, go carefully because you do not need a broken tap to add to your woes.

if/when you drill, if you have a steady hand and a good eye you can use a hand drill. Otherwise it would be wise to use a drill press. The advantage of having set up the drill press is that when you do use the tap you can use a nail in the drill's chuck as a "center' for the helicoil tap which makes it more likely that you will get the thread dead straight.