Stripped thread in 787 engine block

[CReynoldsMIZ]

Ok, my friend and i were trying to get his 97 SPX winterized, when i noticed a problem. I put my hand on the engine exhaust and the engine rocked really bad. I took off the PTO cover and noticed that two of the bolts that bolt the block to the rear engine mount were very loose. They would be the two bolts on the exhaust side of the engine. I was able to tighten one of them, but the other one had absolutely no threads left in the block. I can literally slide the bolt in and out without resistance. Because of this the engine can move alot and it moves the driveshaft with it. My question is, what are my options. The engine has never been apart on this, and it runs good, and the owner really isnt thrilled about pulling it out. Could i possibly support the engine with something, take off the rear brace, and tap a new thread into the block? I have never heard of this happening, and honestly dont know why it happened, but it did. What would you guys suggest? Thanks

 

[brock1]

your best bet would be to tap it.....i would say use a helicoil but i think the vibration may shake it loose ...just tap it to the next size

 

[CReynoldsMIZ]

do you think that it can be done with the engine in the ski, or would it need to come out.

 

[racerxxx]

Your talking the horseshoe engine mount on the back. There is 5 bolts all together. If only one is stripped, carefully remove them one at a time and put some red loctite on it, clean each hole with brake clean or starting fluid(watch the overspary on painted surfaces). One at a time, and just leave the stripped one out. If it were me I'd pull it and Helicoil it, we build equipment that is under constant vibration and use helicoils all the time for repairs. Heck, people have been using them for stripped sparkplug holes for years. But loctite it up and get back on the water.

 

[Coastiejoe]

When done properly, a helicoil does a very good job.

If you arworrieded about the helicoil, then if there is enough room, drill and tap the stripped bolt to the next size up, sometime two sizes up, bolt.

They have 90-degree angle drills, that may give you the room you need. If not,,, pulling the motor at least high enough to get to it may be the answer...

 

[SabrToothSqrl]

helicoil. ,