50 thoughts on “Exploded Briggs And Stratton 12Hp Vertical Shaft Engine Autopsy

  1. This is a question from my 83 year old small motors mechanic father…he is trying to fix our neighbours ride on a Briggs and Stratton 12Hp IC motor model 283707 (their first home and can't afford a new mower yet).  He says the timing is out on the valve.  The valve clearance is right but the intake valve is out.  Is it possible that the cam shaft is bent and can that throw the timing out?  

  2. I have a 6 month ols briggs n strat 19.5 hp intek motor on my ride on. I just blew a hole in the side of the block. Any ideas on this?

  3. i agree, 95% of the failures i have seen in the briggs single cylinders are from the counter balancers flying apart, however the briggs v-twins are very very durable engines.

  4. do most small engines have keyways on the end of the crank? because im taking apart a newer smaller b&s and can't get the bottom flange off the crankshaft…

  5. what year was that briggs made? I have a 11hp version of this motor, its a late 70's model, and it has the syncro balancer thing, and it still runs and what not but, has a rattle when revved up by the govnered throttle, sounds like somthings loose in there but doesn't effect how its running. But on my rider(which don't cut grass anymore, more like modded mower)i swapped out the 11hp for my 19.5hp opposed twin, runs really nice and has power.

  6. Sorry that I took so long to answer. My Briggs engine was on a Sears Craftman and after the autopsy I found that the crank broke at the journal, one counterweight and the connecting rod are gone. The rest is fine. So the engine will be salvage and rebuilt from donors. Since 7 months ago, I was fortunate enough to gather 2 other engines and 4 riding mowers for free.

  7. A good friend of mine bought a tractor with the exact same engine on it..only thing wrong with it is the hand-sized hole in the back of it…rodcap came loose so the piston rod flew through the block…

  8. @sailorchaos1274 I've seen at least 12 identical failures, it really is a terrible design and engineering work.

    Honda GV series engines don't do it, I've only seen one fail catastrophically and it was because the owner bypassed the governor and over-revved it

  9. It's Funny.. I'm rebuilding this same model brigs (12.5 HP) because the fucking rod cap "rattled loose".. I have never seen an engine designed so poorly, especially a Briggs. But for some reason, every video I see of this engine model has spontaneously "came apart".. I think Briggs should get sued over this as it isn't just a one engine failure, it seems to be pretty common…

  10. Thats bad you should see the briggs on a John Deere 165 i am working with i just got it running the idiot who worked on it before messed up the timing so bad it blew the cover off the air filter that wasnt bolted bown and the thing was the engine was perfectly fine before he worked on it

  11. @Aussie50 Could beating the crap out of them be the reason of counter weights failure? I have witness some young bastards by-passing the governor of a 12hp briggs just for fun (They weren't the owners of the mower) Sorry for posting this question so late in the game.

  12. I just received one which went bang. A 12hp briggs 281707 that lost a counter balance and nicked the connecting rod. The rest is fine (Thank god ) because I hate to waste a 12 or 12.5 cast bore engine. They last forever if regularly maintained. I only started to fix them as a hobby one month ago and salvaged a tiller 5 hp from the morgue.A valve was stuck open due to a lack of maintenance. New filters, a coil,shellac washed away and a new diaphragm,new spark plug and oil.Its alive under $25.00.

  13. @frosty9595 the old 70's ones are fantastic!, last forever with oil changes as you said!.

    these new ones like i autopsied had a big weakenss!. being the counter balance weight!

  14. yeah, it happens all the time here, particually push mowers, half the people who own them think of them as 'that thing in the shed that cuts grass" and have no mechanical aptitude whatsoever.
    they run 'em till they die then they end up on the pile at the junk yard with the rest of them

  15. @Aussie50 how much do you pay a month, because i only get 12 GB on my monthly allowance and they charge 70 bucks.

  16. MR Aussi , the sound on this vid is oke , but i meant an older video , but like Dave of Davesfarm always says ; explosions , bangs and blood are good for ratings , greetings from The Netherlands , DUTCHURBANMINER

  17. That Honda GV400 is a reasonably old engine, probably mid-80s or earlier. They don't make L-head engines anymore.

  18. you could say that engine is NFG. i tried making my 3.5HP pop like that and no luck and the spark plug looked worse that that one did.lol. think the problem with my one was it was so fucked it could not over rev.haha

  19. this is like what i saw when i was helping out a mechanic friend of mine he was changing brake pads on an Asian persons car and the disks where gridded in 1 ONE centimeter i almost had a heart attack

  20. lol it won;t fall apart with what i have in store.

    its not a mower anymore, blade deck has been cut off and discarded 😀

    I'll double the final drive ratio and turn it into a crude gocart.

  21. Yeah, that sucks otherwise it would prolly be ok still.

    If the Honda fits, that's a sweet lil ride on, just hope it dont fall apart anymore than it is now lol.

  22. yeah the whole mower was run into the ground, though they re-welded the mower chassis many times!

    The Honda GV400 may drop on as a replacement tho.

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