I have a Briggs I/C 16.5hp OHV 310707 model engine that was given to me on an old riding mower. The old mower had been left to rot for like 3 years and I surprisingly had it running in like 30 minutes. The first thing I did was give it a fresh fill of synthetic 10W30 as the oil had been neglected. This is one of the ones without an oil filter so the new oil looked pretty dirty right off the bat as it began to dissolve the old sludge deposits. The engine actually ran pretty well with no obvious oil burning or knocks so I figured I might have gotten lucky. It mowed the yard with plenty of power until it went POOF and let out a cloud of smoke and just died. The engine had no compression so I figured it had just thrown a rod. Anyway, I thought it was odd that there was no prior warning and began to re-think my first assumption that a rod had let go as there were no signs of external damage. Anyway, I can tell the piston is still present and moves up and down so I know the rod isn't busted. Then I decided to pull the valve cover and things got interesting. The intake valve had lost its keeper and gone into the cylinder. It had done this at least twice as I could see two holes in the head where the valve had been blasted back through the top of the head by the piston. It remains lodged in the head where it went through the second time. The spring, keeper, chunks of cast aluminum from the head, and part of the valve guide and seal were laying inside the valve cover. The rocker arm and pushrod appear to have survived.
I haven't pulled the head off this yet but it doesn't look like a hard job. I know it will need a completely new head as this one is destroyed and also figure I will need to remove the head to evaluate if the engine is worth saving or not. I would plan to keep the rest of the mower as you can find used engines from time to time even if this engine is scrap. Anyone else had a similar experience? My main concern is that there may be visible or more worrisome invisible damage to the piston and rod if I were to fix this. Of course if I see a hole in the piston, I will probably just pull it off and scrap the thing. Anyone have advice on this? Also, why would something like this happen?
I drained the oil right after this happened as it was starting to get dark and I didn't want to have any unseen damage allow an entire fill of oil to drain in the yard that night. I poured the oil into a bottle from the pan the next morning and I didn't notice any worrisome metal chunks or flakes in the oil so I am guessing this is a good sign.
I haven't pulled the head off this yet but it doesn't look like a hard job. I know it will need a completely new head as this one is destroyed and also figure I will need to remove the head to evaluate if the engine is worth saving or not. I would plan to keep the rest of the mower as you can find used engines from time to time even if this engine is scrap. Anyone else had a similar experience? My main concern is that there may be visible or more worrisome invisible damage to the piston and rod if I were to fix this. Of course if I see a hole in the piston, I will probably just pull it off and scrap the thing. Anyone have advice on this? Also, why would something like this happen?
I drained the oil right after this happened as it was starting to get dark and I didn't want to have any unseen damage allow an entire fill of oil to drain in the yard that night. I poured the oil into a bottle from the pan the next morning and I didn't notice any worrisome metal chunks or flakes in the oil so I am guessing this is a good sign.
