Stripped Engine Mount Bolts
Posted July 06, 2012 - 07:46 AM
I removed the engine, welded up and rebored the damaged plate, and now it's time to repair the threads in the case. At the time I should have taken a close look at the case to see how much room was available for either a helicoil style repair or a thread insert. I'm leaning toward drilling and tapping for an insert rather than the helicoil. The insert requires a 9/16 - 12 tapped hole and the helicoil requirs a .397 drilled hole before tapping with the special tap.
Has anyone made this type of repair, and if so which route did you take? As I said earlier I'm leaning toward the insert but since the tractor isn't here I'm not sure there's enough room in the case to drill and tap that large a hole and still have sufficient strength. Another complication is that someone has already tried to helicoil the front mounting hole on the same side. They did a poor job and the coil isn't flush with the bottom of the case. At best I'll have to remove and replace it.
Posted July 06, 2012 - 03:03 PM
Posted July 06, 2012 - 05:53 PM
Posted July 06, 2012 - 08:22 PM
The other thought is that the original holes were drilled and tapped into an aluminum oil pan. Since they failed once due to vibration I would think it could happen again. The thread inserts are hardened steel so they are less likely to strip out. They're also self locking so they won't vibrate out of the pan. Keep in mind whatever size I go to I'll have to find the appropriate flat head bolts to keep as close to the riginal mounting system as possible
Posted July 06, 2012 - 08:26 PM
Posted July 06, 2012 - 08:39 PM
Yours I think has the flat oil pan, where this one has the sump, but they are much the same in the blind hole areas. From the outside, it appears they have a wide area of material for tapping larger, but inside they don't have all that much material. Here's a couple pics to give you an idea. In the 2nd pic, I am pointing to the area the threads are under. I think enough to tap for 7/16 threads, but I'd not dare go 9/16 myself.
Posted July 07, 2012 - 07:10 AM
the pics do not appear in order, but take a look at them all and you'll know how to go about this process...
- bgkid2966 said thank you
Posted July 07, 2012 - 08:32 AM
Posted July 07, 2012 - 08:34 AM
Thanks again projectnut
Posted July 07, 2012 - 09:02 AM
Thanks Olcowhand & NutCASE. It looks like the Helicoil insert is the only way to go. I've used them in the past but generally prefer the inserts whenever possible. In this case It doesn't look like there's much choice.
Thanks again projectnut
There may be another 'choice' but the helicoil for this application works great and is rather inexpensive...The previous poster said use a piece of tape, you should use a drill stop which is a ring with an allen screw in it so you cannot drill to deep...but measure so you know precisely...GL
Edited by NutCASE, July 07, 2012 - 09:03 AM.
Posted July 13, 2012 - 06:47 AM
Everything's back together and better than ever. While I had the engine out I found a few other bolts that had loosened over the years so I replaced a few and tightened a few more. No shakes no rattles, no unusual noises. The thing now runs better and quieter than it has since I started using it.
Along the way I also converted the home made weight bracket to accept a winch. Now I can easily drag brush up the hill without having to continually perform death defying acts.
- CASENUT said thank you