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Oil accumulating in mower belt pulley above the clutch. Need to try to replace oil seal above the clutch but so far have been unable to loosen the bolt on the shaft beneath the clutch. Dumb question: does this bolt loosen in the universal direction -- counter-clockwise and, as I suspect, does it take an impact wrench to loosen it? Once the clutch is removed, what else, if anything, needs to be removed in order to access the old oil seal (Part No. 805049S)?

Since no one else has bother to answer.

Most PTO retaining screws are RH threaded. Yes you may need an impact to get it loose as some have Loctite on threads. And after the PTO clutch is off then you need remove the drive pulley and any key stock.

Now if you pull the seal while the engine still has oil in it be prepare to catch the oil running out. Some only a small amount coming out and others have a lot coming out; just depends the design. Even with the oil removed from engine there will some oil to run out.

When reinstalling the PTO bolt don't use an impact but instead use a torque wrench tighten to spec. Over tightening will lead to bearing failure and under tightening will lead to clutch falling off. Some clutches have a double "D" adapter that you can hold with a wrench and others don't . Those that don't you must hold the flywheel when torquing down the retaining screw.

Also when disassembling and re-assembly pay attention if addition washers are used and orientation of the parts.

StarTech said:

Since no one else has bother to answer.

Most PTO retaining screws are RH threaded. Yes you may need an impact to get it loose as some have Loctite on threads. And after the PTO clutch is off then you need remove the drive pulley and any key stock.

Now if you pull the seal while the engine still has oil in it be prepare to catch the oil running out. Some only a small amount coming out and others have a lot coming out; just depends the design. Even with the oil removed from engine there will some oil to run out.

When reinstalling the PTO bolt don't use an impact but instead use a torque wrench tighten to spec. Over tightening will lead to bearing failure and under tightening will lead to clutch falling off. Some clutches have a double "D" adapter that you can hold with a wrench and others don't . Those that don't you must hold the flywheel when torquing down the retaining screw.

Also when disassembling and re-assembly pay attention if addition washers are used and orientation of the parts.

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Star Tech,

Thank you for furthering my never-ending education. What torque level is recommended for reassembly as the operator's manual for the Tiger Cub and B&S Operating Manual for the Vanguard 23 HP engine fail to contain that spec.

Pretty sure it going to be the 7/16-20 retaining screw but here is a chart just in case it not. Very doubtful it going to be M10.

Just hit it with an impact driver, just don't let it sit there and pound when installing. It is a nightmare to try and hold the engine from turning to torque it with a wrench. It is a 3/8" fine thread interference thread, grade 5. Grade 8 is too brittle to expand and contract with heat..Aternately, pick up a 50 lb. ft. torque stick for your impact wrench to prevent over torquing.

kbowley said:

Just hit it with an impact driver, just don't let it sit there and pound when installing. It is a nightmare to try and hold the engine from turning to torque it with a wrench. It is a 3/8" fine thread interference thread, grade 5. Grade 8 is too brittle to expand and contract with heat..Aternately, pick up a 50 lb. ft. torque stick for your impact wrench to prevent over torquing.

Click to expand...

Are you really sure about the screw/bolt size for the Briggs Vanguard 23hp?


And even the horizontal shaft version can come in one of three different sizes. This is why we must have the engine model and type numbers before barking it is one particular size as many of us work on too many different engines to know without looking up a particular engine. I fairly certain the Scag would not have a taper shaft version.



It not that hard when you know what you are doing to torque the screw. I done replace two new PTO clutches this year because someone using an impact to install them.
And BTW my impact doesn't attempt to stop until it around 85 ft/lbs.

Plus those clutches with the double "D" adapter I have a custom holding tool for them.

Yes, I am. With a 5/8" head. Maybe you should pick up a torque stick?

Thank you. The Vanguard engine model is 386777-0122-E1

Definitely a 7/16-20 screw.

I have found that you can usually take a pair of 10CR vise grip pliers that are made to hold round objects. You can usually get them between the clutch and engine pulley or above the engine pulley and lock them down. They will most of the time stop against something on the mower and you can torque the bolt to the proper torque. I sometimes have to take a shaft and stick in through a hole in the frame and let the vise grips stop against it. Of course you have to let bottom of the shaft rest against something as well. I guess I am lucky in that respect since I have the luxury of working off a lift and lock a pair of vise grips on the shaft and let in rest on the arm of the lift.

Thank you, again. 50-55 foot pounds of torque it will be if all before that step goes well. It was cumbersome to try to hold the shaft from turning with a channel lock while unsuccessfully trying to loosen the bolt with a regular socket wrench as the shaft would still turn. I discovered the shaft has a small hole in it above the mower-belt pulley that may temporarily accommodate a small screw and, if so, render use of the channel lock more effective in keeping the shaft from turning, particularly against no more than 50-55 pounds of torque. Thus, assuming I have better luck getting the bolt off with an impact wrench, in tightening the bolt with a torque wrench, the temporary screw and channel lock will hopefully counterbalance the required torque without the shaft turning. At least, that's my current plan. Thanks, again, for your time and expertise to date.

StarTech said:

View attachment 69325

Definitely a 7/16-20 screw.

Click to expand...

I stand corrected, most engines have a 1" shaft. Either way, torque to roughly 50 lb. ft.
You can pick one up here and get it in a day. It is far easier than dealing with trying to hold the shaft.

Never had a pair of 10CR vise grips slip while torquing a clutch bolt if I get them tight enough.

Have removed the PTO clutch but am stuck on trying to remove the drive pulley in order to access the oil seal without having to remove the engine. Copious amounts of penetrating lubricant and exhaustively researching videos about different ways for loosening the drive pulley or the 3" key on the drive pulley have failed to budge either. I believe the vanguard 23 hp engine and Tiger Cat were both built in 2007. Engine model no. 386777-0122-E1. Bought it from a local dealer in TPA (who no longer handles Scag) supposedly new in July, 2009 but now suspect that it may have been prettied up and worked on for sale as new. Has leaked oil for as long as I remember but not bad until 2020 when it literally caught fire. An authorized Scag dealer got it up and running for under $1k. Ever since then it has leaked worse and about a year ago oil started frequently collecting in the drive and mower clutch pulley and the mower deck is now black with flung oil. The same local authorized scag dealer ignored my repeated calls about the leak throughout all of 2024 which led to my trying to research and fix the worsening oil leak problem myself. Even if I continue down the self-education DIY route, I am not sure that I will be able to get the drive pulley off w/o removal of the engine. Given the engine's oil leak and fire history and the dealer who got it up and running after the first fire and a second fire several months later that was not as bad, probably more oil and less gas, but never remedied the leaks permanently or properly, I likely will need to replace all engine gaskets from which oil and/or gas might leak even if drive shaft oil seal may be the worst leak culprit and I can get the drive pulley off after the engine has been removed. Should I be considering a new Vanguard engine through a reputable dealer with expertise and integrity or have such a dealer try to salvage the existing engine? While a new Vanguard engine is not cheap, it may still be less than trying to properly remedy the leaks on the existing engine. Thank you in advance for your time, expertise, and any input you may wish to offer. Jeff