What to do....

[Scrubcadet10]

Got a Briggs model 12 push mower engine, Quantum.
Owner stripped out crankcase bolt threads while attempting to replace pan gasket.
Evidentlt he had a 5/16 tap.......so he drilled a 5/16 hole......... and broke through into the valves behind the valve cover.
i guess my only option is to tap the hole with the appropriate size tap?
im not sure what to do about the hole into the valve chamber.
Pics soon.
Oooh Friday.

 

[Scrubcadet10]

pics

https://postimg.cc/gallery/7zs1C15

 

[Rivets]

In this case I would do one of two things, depending on what the customer wants to pay. Cheaper way, but no guarantees, JB Weld. Expensive, have the hole TIG welded. On the other holes I would use HeliCoil instead of trying to tap oversize if possible. I doubt you will have enough material to tap oversize, might not even have enough material to use HeliCoils. You’re going to have to do some investigation before making any decisions. Many times neither solution is possible.

 

[MParr]

Inform the owner that he should be prepared in case the engine needs to be scrapped.

 

[sgkent]

First I would be cautious of what I could guarantee the owner. I don't know what size that hole is supposed to be. One option is helicoil or threadcert, then use lots of sealant on it and the bolt. Another, if the original bolt is smaller, thread the area, and put in a soft bolt of that size with lots of Loctite or epoxy like JB Weld. Cut the head off, file flat, and drill for the smaller bolt that should be there. If there is a gasket on the exterior surface or flange then filing may damage that surface, so may TIG welding. A stepped stud might work too if you can get the sizes you want.

 

[StarTech]

5/16 drill bit mean a 3/8-16 tap normally. Now to install Heli coil the bit is only 1/64 larger (21/64) so that is a good possibility but make use thread sealant. Now of course the finish thread hole will be a little larger, closer 3/8 overall.

 

[Scrubcadet10]

to clear things up this is the only hole that is stripped.
So only the 5/16 oversized hole needs attention....

 

[Scrubcadet10]

tapped the hole 3/8-16... cleaned out the engine, aluminum chips etc, i put some thread sealant on the threads as well as a copper sealing/crush washer i had under the head of the bolt... since there is a hole in the valve chamber... with the bolt in, the hole leads to nowhere, now.
Ran it for just over an hour,no leaks or smoke.

 

[7394]