I figured my posting would get noticed in the general section.

A friend has a '95 Dyna which is blowing head gaskets because of stripped threads for the head bolts. I haven't torn it down yet, so my question is... Is this a common problem, and is it repairable with thread repair kits like Heli Coil?

Any input is appreciated.

 

i believe that it is but I would suggest that a shop install them! Another repair that you can look into is Tig welding the thread holes full & re drill them Than re tap brand new threads.
Hatch.

 

Heli-coil is the stronger repair,welding and re-drilling is more work,and you risk getting air pockets in a hole-fill weld,and not getting full thread holding when torqued down.

 

With my automotive background I had good success with Heli Coil. Seems like it ought to be a slam dunk.

 

Helicoils/thread inserts are a good repair if done correctly.

 

First off those use a long stud that threads into the cases . isn't any threads in the heads themselves . First make sure it isn't a weak stud stretching which the stock ones would do and then look at the case area . Standard repair on those is a one piece insert if the case isn't shot and in need of welding .

Don't attempt a helicoil in this application weakens the area and can allow the headbolt to lock onto the stud and pull the whole stud out , whole motor comes out then .

 

I think that's the info I was looking for. Ok thanks. Gotta start somewhere, so here goes. Keep you posted. Thank you!

 

So your saying to use a Timesert or Keensert.

How does using a Helicoil/thread insert weaken the case?

 

Helicoils are ok for most jobs but tend to be a looser fit than the one piece units and they don't do real well with critical torque application in softer metals like the early evo cases and the case stud area is thin already plus that's a critical fastener , since the studs need to be loctited down the helicoil usually comes out with the stud again causing a bigger problem . Google case stud repair and read some of the horror stories .

Check around the local indie shops Jim's makes a jig tool just for this job maybe they can rent or loan it to you ????

 

I was going to stay out of this. Every once in awhile something better than what I have seen hits the market. I have never used the insert but the tig wielding re-tapping I have done. It works, but if it doesn't then it makes lots of work. I hate helicoils for anything that will see what I call real torque. Real torque to me is anything over 30 ft lbs. I am more into prevention of this kind of crap than repair.