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Briggs engine Knock 310707 17hp IC

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kcp877

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Discussion starter · #1 ·
Had a pretty good engine knock, had a few people say the same, connecting rod/wrist pin should be replaced before it goes through the side of the engine. Tore the engine apart today, aside from tons of carbon on the piston everything looks ok. The connecting rod doesn't look worn, it looked tight, no slop before I unbolted it. The only thing i noticed was at the bottom of the cylinder where it ends and goes into the crankcase, the metal had some spots where it was flaking off a little on the edge, so i'm assuming the piston was making the knocking noise at the bottom of the stroke, but i'm not positive. would that mean the rings were toast?
Need some advice, not sure what to replace since I was expecting to find a lot of slop when it was apart.
 
Discussion starter · #3 ·
Not sure how to check the balancer? pull the flywheel? Anyone got any tricks to getting that off without buying a puller? Its quiet and smooth when spun by hand with the plug out, no noises.
 
#4 ·
Well I think I mentioned some time ago that it might be the counter balance bearings. The only way I know to check is to remove the sump, take a hold of the actual weight and see if it moves more than a very few thousandths side to side. The top one is likely to be worn the most. You DO NOT remove the flywheel, that will get you no where.

There is no economically feasible way to repair this condition unless you are an expert machinist or know one who will work for nothing.

Walt Conner
 
Discussion starter · #5 ·
Forgive me for describing parts because my manual is still not in my mailbox yet. I took everything apart. I asume the counterbalance part is the oblong that rotates the crank up and down, that is tight, no slop. If i spin the flywheel disassembled that does wobble up and down as a whole piece, but thats because the shaft isn't secured on the other side.

When fully assembled if I flip it with the shaft going down into the workbench and grab the flywheel and push hard with my thumbs against the engine i can get a slight movement, but that is up and down, not side to side.
 
Discussion starter · #7 ·
cylinder looked good, tight around piston, rod was tight around crank, everything looked good. its back together, just haven't been home from work early enough to fire it up and see if it was carbon knock.
 
#8 ·
Hi Kevin,
I had an engine knock develop in my 1970 GT B&S 15. Took it to a small engine mechanic that specializes in Craftsman GT's and he knew just what it was. He cleaned the carbon off the heads just like you did and the knock was gone. Didn't even charge me. He just smilled and said if you ever want to sale her call me first. That was 25 years ago and she still runs like the sweet thing she is.
I hope that solves your problem too.
 
#9 ·
Well guys heres the problem im sure u all know this by now but im going to say the human is not calibrated enough to see what may cause a knock get out the mic and calipers and platiguage and start measuing and checking tolerences by the book this will most definitely find it
 
#11 ·
kcp877 said:
Had a pretty good engine knock, had a few people say the same, connecting rod/wrist pin should be replaced before it goes through the side of the engine. Tore the engine apart today, aside from tons of carbon on the piston everything looks ok. The connecting rod doesn't look worn, it looked tight, no slop before I unbolted it. The only thing i noticed was at the bottom of the cylinder where it ends and goes into the crankcase, the metal had some spots where it was flaking off a little on the edge, so i'm assuming the piston was making the knocking noise at the bottom of the stroke, but i'm not positive. would that mean the rings were toast?
Need some advice, not sure what to replace since I was expecting to find a lot of slop when it was apart.
Click to expand...
Tons of carbon is probably the knock , clean the carbon off piston & head .. run it ? See if knock went away 😎
 
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