Briggs and Stratton 11hp shaking/off balance

steveric · 10-19-2009, 10:51 PM

I have a B & S 11hp in my John Deere 111 that seems to have developed a shake like it threw a counter weight internally...

This shake developed after the engine got pretty hot and low on oil at the same time (gold star for me!)...

The shake seems to follow the rpms, that is it shakes more with higher rpms, less with lower rpms...

I've already pulled and cleaned the flywheel (thinking that maybe was off balance there) no change, and nothing apeared to be missing.

Today I finally broke down and pulled the engine out of the tractor, opened the case and noticed some metal pieces in the sump, not chunks more like shavings or a chewed up shim (really chewed up). The pieces are magnetic aka steel.

While rotating the crank I noticed that it looks like there is a bit more slop in the counterweight assy. to crankshaft connection than I think there should be?. The slop is between the "eccentric" and the counterweight assy. not sure what the tolarance(s) should be? So this is one place I thought might be causing the shake?

The model is: 252707
Type: 0675-01

Thanks in advance!

mstpops · 11-08-2009, 11:32 PM

sounds like the counter weight bearings have worn out on their journal
i suspect the engine has a knock as well - this could have a link rod to limit side ways travel in the c/case - but i think the counter weight bearings are non replaceable
you might well be looking at another counter weight assy in good condition if you can find one - or another engine might even be cheaper given parts required to repair

mstpops

steveric · 11-09-2009, 06:45 AM

Thanks for the reply mstpops, you are correct, the upper counter weight bearing failed or at least exceeded tolarences and was causing the shake and yes a knock!

I actually tore the engine down about 2 weeks ago and found the problem which looked like some one had tried to "fix" by puting some other type of sleave in the bearings place.

So I replaced the two eccentrics (due to wear) and the counter weight assembly. I ended up breaking and drilling out the timing key. So with the replacement base gasket and a new timing gear dowl pin (first time I've seen a dowel/ T shaped key) the total was about $60 in parts over the internet from M&D Mower Repair out of Ohio!

I got it back together Friday (3 days ago) and started her up saturday, then mulched and bagged leaves most of the last two days with a smoother running engine!

I spoke to a "retired" small engine mechanic out of a local shop and he had some of the same thoughts as you about the price and availablity of parts making the fix too eccentric (pun intended!).

Now I have to decide if I want to pursue the oil burning (blue smoke) I'm getting, maybe I just overfilled it a bit....

10-19-2009, 10:51 PM	#1 (permalink)
steveric Registered User Join Date: Oct 2009 Posts: 2 OS: vista	Briggs and Stratton 11hp shaking/off balance I have a B & S 11hp in my John Deere 111 that seems to have developed a shake like it threw a counter weight internally... This shake developed after the engine got pretty hot and low on oil at the same time (gold star for me!)... The shake seems to follow the rpms, that is it shakes more with higher rpms, less with lower rpms... I've already pulled and cleaned the flywheel (thinking that maybe was off balance there) no change, and nothing apeared to be missing. Today I finally broke down and pulled the engine out of the tractor, opened the case and noticed some metal pieces in the sump, not chunks more like shavings or a chewed up shim (really chewed up). The pieces are magnetic aka steel. While rotating the crank I noticed that it looks like there is a bit more slop in the counterweight assy. to crankshaft connection than I think there should be?. The slop is between the "eccentric" and the counterweight assy. not sure what the tolarance(s) should be? So this is one place I thought might be causing the shake? The model is: 252707 Type: 0675-01 Thanks in advance!

11-08-2009, 11:32 PM	#2 (permalink)
mstpops Registered User Join Date: Oct 2009 Posts: 18 OS: xp	Re: Briggs and Stratton 11hp shaking/off balance sounds like the counter weight bearings have worn out on their journal i suspect the engine has a knock as well - this could have a link rod to limit side ways travel in the c/case - but i think the counter weight bearings are non replaceable you might well be looking at another counter weight assy in good condition if you can find one - or another engine might even be cheaper given parts required to repair mstpops

11-09-2009, 06:45 AM	#3 (permalink)
steveric Registered User Join Date: Oct 2009 Posts: 2 OS: vista	Re: Briggs and Stratton 11hp shaking/off balance Thanks for the reply mstpops, you are correct, the upper counter weight bearing failed or at least exceeded tolarences and was causing the shake and yes a knock! I actually tore the engine down about 2 weeks ago and found the problem which looked like some one had tried to "fix" by puting some other type of sleave in the bearings place. So I replaced the two eccentrics (due to wear) and the counter weight assembly. I ended up breaking and drilling out the timing key. So with the replacement base gasket and a new timing gear dowl pin (first time I've seen a dowel/ T shaped key) the total was about $60 in parts over the internet from M&D Mower Repair out of Ohio! I got it back together Friday (3 days ago) and started her up saturday, then mulched and bagged leaves most of the last two days with a smoother running engine! I spoke to a "retired" small engine mechanic out of a local shop and he had some of the same thoughts as you about the price and availablity of parts making the fix too eccentric (pun intended!). Now I have to decide if I want to pursue the oil burning (blue smoke) I'm getting, maybe I just overfilled it a bit....