6640 Front axle support broken bolts

Jackfr · Aug 1, 2010

While installing new spool valvel we found that the bolts that attach the front axle support to the engine were loose or broken. The left front was sheared in the support, which we drilled and used an easy out to get out (no fun) and one of the ears on the oil pan was partially broken off. We used big washers on that it seems like it will be ok. My question is should I put new 3/4"x3" grade 5 bolts back in or should I use grade 8. Should I use lock tight so they won't loosen again? My fear is if the grade 8 break or if I use lock tight we won't be able to use easy outs to get them out if they break again. We ususally go over all the bolts when we service our tractors so I don't know how this happened so quickly.

Here are some pictures of the broken bolt we drilled and then used an easy out on it(about three hours using an angle drill attachment) the broken oil pan casting where it attaches to the front axle support what the casting should look like and the new bolt that replaced the broken one

Jerry/MT · Aug 2, 2010

Jackfr said:
While installing new spool valvel we found that the bolts that attach the front axle support to the engine were loose or broken. The left front was sheared in the support, which we drilled and used an easy out to get out (no fun) and one of the ears on the oil pan was partially broken off. We used big washers on that it seems like it will be ok. My question is should I put new 3/4"x3" grade 5 bolts back in or should I use grade 8. Should I use lock tight so they won't loosen again? My fear is if the grade 8 break or if I use lock tight we won't be able to use easy outs to get them out if they break again. We ususally go over all the bolts when we service our tractors so I don't know how this happened so quickly.

Here are some pictures of the broken bolt we drilled and then used an easy out on it(about three hours using an angle drill attachment) the broken oil pan casting where it attaches to the front axle support what the casting should look like and the new bolt that replaced the broken one

I'm certainly no expert, but that bolt looks like it failed in torsion not shear. The leftover chunk sticking up on the bolt head piece makes me think that.

I'd replace thee bolts with the same grade as the old bolts, and use some of the "not forever" Loctite on them to keep them from losening due to vibration. If you go to a higher grade bolt it might hold and a casting will crack the next time if what ever caused this damage occurs again.