# Craftsman 20hp motor locked up?



## bripatch1 (Jun 13, 2011)

Craftsman Twin model 917.270940 with 42" mower deck has recently
become harder and harder to crank over to the point now that even with
the plugs removed and turning by hand its difficult to move at all. (with the
covers off and the cooling fan removed I'm using a box wrench on the main 
flywheel nut). The mower deck is disengaged and has a new 95.5" drive belt so 
the drive pulley is free to move. Any thoughts would be appreciated,
Regards, Bripatch1


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## wjjones (May 28, 2010)

Well our local mower mechanic, and neighbor was telling me that the weight of oil can cause this problem as well as old oil that hasnt been changed for awhile.. What type of oil do you use, and how often do you change it? Another thing you might check is your flywheel key to be sure it is intact, and hasnt broke enough to let it out of time a hair.


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## dangeroustoys56 (Jul 26, 2010)

Try smelling the oil and see if any gas got into it - if it did, the oil can thin out and ruin the berings, creating the turning issue.

Is it a flathead or v twin? Flatheads would be easier to check by simply pulling the head, v twins require pulling the rockers and heads off.

It sounds like it was oil starved - does it have an oil pump or splash lubricated? Oil pump type motor would use a oil filter.


One more thing you want to check - the magneto- i have a 90 murray that the magneto loosened and slid against the flywheel, it turns but turned hard.


If none of those seem to be the cause, then its time to crack the motor open and investigate.


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## Larry in OK (Jul 22, 2010)

Take off the side cover of the engine. Mine threw a con rod and totally destroyed the engine.
My postmortem was that the bolts holding the rod cap had backed off.
From what I was able to find out, it is a fairly common problem with the 20 hp Brigs engines.
I'll likely never buy another new Brigs engine. The 26 hp Kohler I have in my current Craftsman rider is exponentially a better machine.


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## jhngardner367 (Apr 5, 2011)

*engine*

That engine is a flat-head twin,with an oil pump.It sounds as though either the oil pump isn't working,OR you have a plugged filter. Try this: remove the sparkplugs,and spray some PB Blaster into the cylinders,then remove the oil filter,and try to crank the engine over,to see if any oil comes out of the filter area.NOTE!Have rags/towels ready to catch the spray! If,after 4-5 revolutions,you don't see oil flow,the pump isn't working.It can be removed from the bottom of the sump(engine removed),and while it's off,turn the engine by hand,and watch the pump drive,for movement.


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## dangeroustoys56 (Jul 26, 2010)

Larry in OK : My nephew's father had me swap motors on his one tractor ( he later junked i found out) - cracked open the back to find one rod still together- the other totally gone - still turned over tho.

I dont like 'newer' briggs motors, weak anemic plastic filled for EPA regs- ill stick with older flathead briggs motors .....


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## ftorleans1 (Jul 12, 2009)

It does sound like oil starvation... Perform the test our fellow comrad stated. Pull the plugs, shoot some light weight lubricating oil in the cylinders and remove the filter. Make sure you have the sump filled with the proper amount of oil and try turning by hand to see if it frees up. If so, you may have a plugged filter or bad pump. Good Luck,
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## Country Boy (Mar 18, 2010)

I had a 20hp opposed twin in my LT1000 I used to have that blew up on me 3 months outside of warranty. When I tore it apart, I found 3 of the 6 rings missing, one of the oil slingers wasn't installed, and the rod had come loose before grenading. I swore then that it would be the last Briggs engine I bought after talking to the company and them basically telling me to piss off and said I was lying to them about the missing parts.


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