counterweight knocking? 31H777-0210-E1

[oldntired55]

so, does anyone know the measurement specs on counterweight groove, and the rib it rides on??? i have .005 clearance... when i move it side to side it 'knocks'

 

[Forest#2]

so, does anyone know the measurement specs on counterweight groove, and the rib it rides on??? i have .005 clearance... when i move it side to side it 'knocks'

I do not have any specs. I seen the same thing on my knocking briggs. (counterbalance raised groove surface weat at the sump end)
What you mention is what I also seen on my engine that I mention in post #6 and 9. I could see some wear on the counterweight raised groove on the sump. I installed a counterweight from another engine that had bad crank My engine had .030 crankshaft end play using the sump gasket. I shimmed the crankshaft at the sump end to reduce the end play to .005. It slightly changed the tone of the knock.
I'm thinking I should have shimmed the flywheel end of the crankshaft so as to reduce the counterweight clearance at the sump end at the raised groove.
I just set the engine back for maybe sometime later. I thought about just removing the counterbalance and trying the engine at low idle and see if it still knocked or maybe another sump from a salvage engine. I could also see where the counterbalance has been banging on the raised aluminum groove. I just recently had a donor engine come to me non-running so I now maybe have some donor parts to try and take two and make one or have parts to sub.
It will be few months or cooler weather before I get back into this one.
Keep us informed as the what you try?

 

[oldntired55]

I do not have any specs. I seen the same thing on my knocking briggs. (counterbalance raised groove surface weat at the sump end)
What you mention is what I also seen on my engine that I mention in post #6 and 9. I could see some wear on the counterweight raised groove on the sump. I installed a counterweight from another engine that had bad crank My engine had .030 crankshaft end play using the sump gasket. I shimmed the crankshaft at the sump end to reduce the end play to .005. It slightly changed the tone of the knock.
I'm thinking I should have shimmed the flywheel end of the crankshaft so as to reduce the counterweight clearance at the sump end at the raised groove.
I just set the engine back for maybe sometime later. I thought about just removing the counterbalance and trying the engine at low idle and see if it still knocked or maybe another sump from a salvage engine. I could also see where the counterbalance has been banging on the raised aluminum groove. I just recently had a donor engine come to me non-running so I now maybe have some donor parts to try and take two and make one or have parts to sub.
It will be few months or cooler weather before I get back into this one.
Keep us informed as the what you try?

yesterday i was between jobs in my shop, i remembered quite a few times using a centerpunch to raise metal for a closer fit.so i put several marks on the edges of the sump. where the weight rides... the counterweight fits alot more snug on the sump. i know it will not be a permanent solution, was just trying to make it tighter. i may do the same inside the counterweight links, as they are at their size limit... so i really cant be sure where the 'knock" was... but im thinking it was the weight rattling... it was quite noticeable.. more later

 

[oldntired55]

yesterday i was between jobs in my shop, i remembered quite a few times using a centerpunch to raise metal for a closer fit.so i put several marks on the edges of the sump. where the weight rides... the counterweight fits alot more snug on the sump. i know it will not be a permanent solution, was just trying to make it tighter. i may do the same inside the counterweight links, as they are at their size limit... so i really cant be sure where the 'knock" was... but im thinking it was the weight rattling... it was quite noticeable.. more later

another thought, i wonder, with all the yrs Briggs has been using plastic internal parts... couldn't they have designed a replaceable nylon sleeve for the counterweight??

 

[StarTech]

The unworn sump guide is .248-.250". Don't have the counter weight currently available to measure the groove.

 

[oldntired55]

The unworn sump guide is .248-.250". Don't have the counter weight currently available to measure the groove.

i need to go measure the sump guide again..im thinking it was on the .248 side..

 

[Auto Doc's]

I have seen worn electric PTO clutches produce a knock at low RPM.... if this has an electric PTO

 

[oldntired55]

I have seen worn electric PTO clutches produce a knock at low RPM.... if this has an electric PTO

no it does not...but tks

 

[oldntired55]

Has anyone tried running one of these engines WITHOUT the counterweight inside??? ready to experiment...i recently acquired another engine, this one a 20hp... same noise...

 

[Forest#2]

Has anyone tried running one of these engines WITHOUT the counterweight inside??? ready to experiment...i recently acquired another engine, this one a 20hp... same noise...

You asked: Has anyone tried running one of these engines WITHOUT the counterweight inside???


I thought about eventually removing the counterbalance with my knocking briggs that I set back but have not had a chance to try such yet. I think the knock on this one is the counterbalance guide groove slapping on the sump guide because when I shimmed the crankshaft end play to minimum the tone of the changed and slightly reduced the knock sound. This made me also think maybe that I should have shimmed the flywheel end of the crankshaft end play to reduce the counterbalance groove gap clearance at the sump groove end. (when I shimmed the crank at the sump end the groove gap would have also increased) I can see the raised sump end aluminum groove slightly worn.
If I had another sump that had a unworn groove I would also sub it.
My knocker Briggs really runs good except for the annoying knock.

Keep us informed as to what you try????