MTD / Briggs engine pulley problems

[lefty]

Well the owner found a bolt on the lawn recently. 7/16 bolt 1.5 inch long. But it looks like a 14. Specs on this machine with the original motor was a 20. I tried it in the crank but it doesn't fit at all. Strange that he had the same length / size bolt lying around on the lawn. I don't have a 7/16-20 to see if that's the pitch. And I was poking around on the internet to try to find out if that's the thread in that shaft but I'm having a hard time. Can I assume the 331777-1107 B1 is going to be a 7/16-20 as well?

Thanks.

[bgsengine]

Yep 7/16-20. Wouldn't surprise me if the "tech" that "fixed" it last time just threw in a 7/16-14 bolt and got 1 thread started just to hold it in place while he went to get a 7/16-20 bolt, and then forgot about it. (best case) or worst case, started it in and snugged it when it wouldn't thread in, and called it fixed

[Arkie]

Yep 7/16-20. Wouldn't surprise me if the "tech" that "fixed" it last time just threw in a 7/16-14 bolt and got 1 thread started just to hold it in place while he went to get a 7/16-20 bolt, and then forgot about it. (best case) or worst case, started it in and snugged it when it wouldn't thread in, and called it fixed

Hopefully the "tech BUBBA just snugged it.

When you find a replacement bolt, if it don't start and thread in easily, don't force it. You may have to get a tap to Chase/clean the threads. Check the depth of the crankshaft threaded hole, might be 1/2 inch or so deeper. (might be some good threads in the bottom of the existing threaded hole. (where a longer bolt can be used as a last resort, maybe)

[lefty]

I finally got a chance to get up to the hardware store and picked up a 7/16-20, 1.5 inch bolt grade 8. It's a perfect match based on the photos I've seen and it threads in easily. So I think that's it. So I'll get a pulley, spacer and belt. The only other thing is the flat washer. I have plenty of lock and flat washers laying around but this one seems special. It's a 7/16 but oversized to 1.25" diameter. I also believe it's about .17 thick. I was unable to find an exact match at the hardware store.

Should I order that part or would one that's pretty close make an adequate substitute? Seems that these basic pieces of hardware, with shipping, get marked up about 800%. I'm pretty sure I'm not alone in this but there's definitely a thrill in finding a use for a fastener from the misc jar rather than purchasing new... so I can say told-ya-so when my wife calls me a hoarder.

Also, does anyone know the torque specs on the bolt?

And lastly, regarding installation. After being enlighted by you fine folks, I now understand why it is not advisable to use a rope in the cylinder when torquing. It makes a lot of sense. But I don't have a strap wrench adequate enough for the flywheel and I'm solo over here. Any other tips for torquing the pulley back on? If I'm careful to put the rope in on the compression stroke with the valves closed is there still a risk of damaging the valves? I'm guessing the answer is yes because of the compression release? Could I maybe hold it by the flywheel nut with a second wrench?

Thanks to all

[bgsengine]

It's a 7/16 but oversized to 1.25" diameter. I also believe it's about .17 thick. I was unable to find an exact match at the hardware store.

MTD part number 736-0322.

Should I order that part or would one that's pretty close make an adequate substitute? Seems that these basic pieces of hardware, with shipping, get marked up about 800%.

No not really. These are very hard to find uncommon flat washers, MTD wants almost $3 apiece at dealer cost for those washers, even with a reasonable markup to cover costs (most distributors are $10 - $11 freight to dealer) you'd be looking at $6+ each plus shipping (and first class mail parcel is around $2.65 - $3.09 depending on zone) so, $8-$9 apiece on those washers is really not that far off the mark.

Also, does anyone know the torque specs on the bolt?

And lastly, regarding installation. After being enlighted by you fine folks, I now understand why it is not advisable to use a rope in the cylinder when torquing. It makes a lot of sense. But I don't have a strap wrench adequate enough for the flywheel and I'm solo over here. Any other tips for torquing the pulley back on? If I'm careful to put the rope in on the compression stroke with the valves closed is there still a risk of damaging the valves? I'm guessing the answer is yes because of the compression release? Could I maybe hold it by the flywheel nut with a second wrench?

Thanks to all

Dont have specs handy but I think it would be around 25 Ft-Lbs or so.. if you got room, sometimes can fit a pipe wrench over middle section of double sheave pulley to hold it in place, or pick up a roll of seat belt webbing somewhere and make your own strap wrench..

[lefty]

Thanks. I think I can get a pipe wrench in there.

[Arkie]

torque specs for 7/16 x20 NF

You can find torque specs for the bolt on-line. Briggs may not list such.

https://www.almabolt.com/pages/catalog/ ... torque.htm

Should be up around at least 40-50 ft lbs for a grade 5. Grade 8 is higher torque but I would not push it to the max for a grade 8 1 1/2 inches long. Might pull a thread. I use a little dab of blue locktite on the cleaned threads. They have a tendency to come loose if not torqued.

[lefty]

Thanks.

[38racing]

7/16 -20 gets torqued to 55 ft lbs if it were an extreme torque electric clutch.
I've used vise grips on the shaft of pulley. There's usually something for the handle to hit.
Edit:
From mtd repair manual for 700 series

Tighten the crankshaft pulley bolt to a torque of 37.5-50 ft-lb. (51-68 Nm).

[lefty]

Thank you. I just finished the job today. Finally got parts in and the time to complete.

So everything went well. Cleaned up the shaft and installed. Torqued to a little under 40, put some anti-seize on the shaft and a bit of Loctite on the bolt. So I think something needs to be adjusted with the new belt from the engine pulley to the deck. This is one of those that raising the deck to the top disengages the blades. But the blades are staying partly engaged even at the top. If I pull back on the handle, the blades will stop but once I take the tension off and let it relax into position, the blades start spinning again.

I found some info on the internet stating that the Rod Disengatement lever needs to be adjusted. I believe it connects to a hole with a pin into the Shaft Assembly Stab per the schematic I was looking at. I believe I need to disconnect it and turn clockwise to cause the deck to move more forward when raised to the top setting. Am I on the right track?

I ran it for about 45 seconds before noticing this problem. The pulley got pretty hot during that time, which I'm guessing is due to the fact that the blades were partially engaged causing a whole lot of friction as the belt kind of slipped on the pulley for that time. It was very hot to the touch.

Once I get this done, she's out of my garage....yay!