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SO... does crack kill flywheels, too?

#1

G

Gumby83

I had to remove the flywheel to replace the crankcase breather as the old one would “squawk” with the last few revolutions after key off. I didn’t figure that out until I was filling it with oil and my brain was going “Steady....
steady....
steady.....

DUMP ALL THE OIL INTO THE FUNNEL AT ONCE!!!” and the excess pressure vented through the breather, creating a much quieter but identical “squawk.” Aha! :unsure:

I noticed the flywheel has a hairline crack in it on the flange surface for the shaft nut. I can’t say for sure how long it’s been there - I don’t remember seeing it the first time I took it off last year, and I’ve only had this engine running for a few minutes since my tear down. I only used a light coating of oil on the shaft (NOT the threads) when installing the flywheel, and I torqued the shaft nut to 150 ft-lbs per the B&S intek service manual I bought. The shaft, key, nut and washer are all in good condition.

I know cast iron tends to continue cracking once it starts, and when fully seated, there’s outward pressure on the flywheel not only from spinning but also from the interference fit on the shaft. I recognize there’s significant chance of injury and/or pants pooping to the operator and bystanders if the flywheel splits completely through.

Keeping that in mind, I’m not sure what to make of this one. It only appears to be in the raised flange area of the flywheel. The crack is visible on the inner and outer surfaces but no light is visible through it when holding a flashlight behind it, and it doesn’t look like it’s extending into the flywheel yet.

I didn’t know if this is a common thing among small engines and it’s nothing to worry about or if.... :poop:

I can take more pics if requested.51AB3B87-2569-4600-96B1-2217B207497E.jpeg89E3438B-E9C5-4673-ABC5-D18A4D0928CB.jpeg1AD01EC9-5087-4CC4-B4B9-D4FCF81053B1.jpeg


#2

Scrubcadet10

Scrubcadet10

I rarely see a cracked flywheel... However, i wouldn't operate it like that much longer at all.


#3

B

bertsmobile1

That flywheel is deceased and what killed it was the oil you put on the taper.
Tapers are always fitted dry


#4

Fish

Fish

Throw it away, A flywheel like that can kill someone.


#5

Hammermechanicman

Hammermechanicman

C'mon man! Have some fun. Fire it up and over rev it till either the rod the govenor gear or flywheel blows. Place your bets gents. ?


#6

Scrubcadet10

Scrubcadet10

get the model and type number off the valve cover, that'll help you get the right one.


#7

Beamster

Beamster

Having designed building structures for over 40 years, cracks in metal are deemed a "run, don't walk" situation.


#8

G

Gord Baker

Gumby83 said:
I had to remove the flywheel to replace the crankcase breather as the old one would “squawk” with the last few revolutions after key off. I didn’t figure that out until I was filling it with oil and my brain was going “Steady....
steady....
steady.....

DUMP ALL THE OIL INTO THE FUNNEL AT ONCE!!!” and the excess pressure vented through the breather, creating a much quieter but identical “squawk.” Aha! :unsure:

I noticed the flywheel has a hairline crack in it on the flange surface for the shaft nut. I can’t say for sure how long it’s been there - I don’t remember seeing it the first time I took it off last year, and I’ve only had this engine running for a few minutes since my tear down. I only used a light coating of oil on the shaft (NOT the threads) when installing the flywheel, and I torqued the shaft nut to 150 ft-lbs per the B&S intek service manual I bought. The shaft, key, nut and washer are all in good condition.

I know cast iron tends to continue cracking once it starts, and when fully seated, there’s outward pressure on the flywheel not only from spinning but also from the interference fit on the shaft. I recognize there’s significant chance of injury and/or pants pooping to the operator and bystanders if the flywheel splits completely through.

Keeping that in mind, I’m not sure what to make of this one. It only appears to be in the raised flange area of the flywheel. The crack is visible on the inner and outer surfaces but no light is visible through it when holding a flashlight behind it, and it doesn’t look like it’s extending into the flywheel yet.

I didn’t know if this is a common thing among small engines and it’s nothing to worry about or if.... :poop:

I can take more pics if requested.View attachment 56028View attachment 56029View attachment 56030
Click to expand...


#9

G

Gord Baker

Nasty situation. I would carefully drill a 1/8" hole at the very base of the Boss at the crack site all the way through the Flywheel until you find a replacement. Do not over tighten, use a New Key.


#10

G

Gumby83

Yeah I figured it was toast... but then I tried to eat it, and even peanut butter didn't help the taste! ?

I did some searching for machine shops in my area that might be able to repair it, but didn't have any luck due to either cost or down time, so I got a replacement flywheel and key ordered directly from Briggs & Stratton's website today (there was too much confusion on part numbers from other websites - I wanted to be sure I'm getting the right one and I wouldn't have saved much going elsewhere).

For clarification - the "light coating of oil" was residual spray lube. Whenever I have an engine apart, I coat all the internal components with spray lube to prevent rust after cleaning. The engine was apart for more than a week before reassembly, so I figured what little coat of lube was left on it could only help to prevent the flywheel and crankshaft from seizing.

I'll inspect the crankshaft more thoroughly before installation to make sure I didn't miss anything else that might have been a contributing factor.

Thanks.


#11

B

biggertv

That was caused by the key not seated properly when nut was torqued. Crank is probably damaged too. Quick and Dirty Unauthorized Fix: Make sure key is lined up. Drill a 3/16 hole thru the fly and crank,Hammer in a roll pin. works like a champ but no fun if you need to remove. Saves a Not Worth Repair situation.


#12

G

Gumby83

Just to conclude this thread...

I didn’t find any problems with the crankshaft taper or key way - the new flywheel fit perfectly and I made sure the taper was completely dry before installing and torquing it.

I did take a second look at the old flywheel and key and found the key actually did have a damaged corner, so I’m sure that also played a part in the flywheel cracking.

Thanks again for the help.

FD2A1BA0-9516-475B-89FE-B5B5D7BA2135.jpeg9A4573BA-922A-476A-9230-B7BB82C95D4A.jpeg


#13

TylerFrankel1

TylerFrankel1

Hate to tell you this but you probably didn't need to mess with anything in the first place. Sometimes breathers are just noisy... I've never noticed any ill effects from them making a little "squak" I think its just the plastic valve material resonating. If it's cracked it's probably dangerous. I can't tell from the pics but is there any chance it's a scratch? Scratch doesn't matter, crack does.

Personally, and I'm not liable for any personal injuries, but personally I'm a cheap bastard and I'd run it and see what happens, keeping a good distance between me and the engine when it was running at first, just for fun. But if you already ordered a replacement definitely don't risk it.


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