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I have a Yard Man riding mower, model #13AC762F755. It's equipped with a Briggs & Stratton "PowerBuilt"13.5 hp engine. Not sure of the model number for the engine as I've been unable to locate it thus far.

The issue:
The other day when I tried to start the engine, the starter would turn the engine over but no ignition. I thought that was unusual because the engine usually starts upon the first or second attempt. After about three attempts the engine suddenly stopped turning when the starter was engaged. In other words, the starter tries to crank the engine (clicks) but the engine doesn't turn. My first thought was that it may be hydro-locked. So I removed the spark plug and tried again, but it made no difference. Even replaced the battery...but still no difference. I noticed that I'm am able to turn the engine by hand in reverse (counterclockwise). But when I turn it back in the forward clockwise direction it will suddenly stop at the same point as though something is blocking/preventing the crankshaft from turning any further. Thus far I've ruled out hydro-lock, the starter, or the battery as being the issue. At this point I'm a little stumped.

Any help on this matter would be greatly appreciated.

Thanks in advance

TRY adjusting the valves .... !

Boobala said:

TRY adjusting the valves .... !

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Are you referring to the valve clearance? I can only relate to your suggestion based on my experience working on motorcycle engines. Valve clearance on those type engines would not have any affect on crank rotation. A detached rocker arm may cause that, but there would be tell-tale engine noises beforehand. In my case there were no prior symptoms. Is there some other type of adjustment you are referring to?

It does on these lawnmower engines. There's a compression release that is highly dependent upon the valve clearance being set correctly.

cpurvis said:

It does on these lawnmower engines. There's a compression release that is highly dependent upon the valve clearance being set correctly.

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As I mentioned, I removed the spark plug thus eliminating any compression, and it still did not work. Is the compression release you speak of somehow unrelated to engine compression? Also, where would I find the valve adjust procedure for this type engine? Thanks

It would help us a lot if we knew what type of engine you have. L Head or OHV type.


If the plug is out and you can turn the engine then it stops or binds up then you might have something loose in there.

Or worse, the rod is shot ~!~!

doodleysquat said:

As I mentioned, I removed the spark plug thus eliminating any compression, and it still did not work. Is the compression release you speak of somehow unrelated to engine compression? Also, where would I find the valve adjust procedure for this type engine? Thanks

Click to expand...

Sorry, I missed the part about removing the plug. That would indeed take the compression release out of the list of suspects.

Carry on.

Boudreaux In Eunice La. said:

It would help us a lot if we knew what type of engine you have. L Head or OHV type.


If the plug is out and you can turn the engine then it stops or binds up then you might have something loose in there.

Or worse, the rod is shot ~!~!

Click to expand...

Okay...I found the engine model number. It's 21B707. It also has a number for "Type", which is 0453E1. From that I was able to find the owners manual. Based on the parts diagram it is a OHV type engine. There definitely seems to be something binding the crank rotation. I can use the flywheel to turn the engine about a half rotation in each direction before it abruptly stops. Any thoughts?

Connecting rod is broke most likely.

Take the spark plug out and stick a screwdriver in the hole. Turn the flywheel BY HAND and see if the piston is moving up and down.............

Boudreaux In Eunice La. said:

Connecting rod is broke most likely.

Take the spark plug out and stick a screwdriver in the hole. Turn the flywheel BY HAND and see if the piston is moving up and down.............

Click to expand...

Good advice. So I tried that and the piston does move up and down. But if I cover the spark plug hole with my finger while turning the crank I feel no compression. I realize that doesn't necessarily mean anything unless it's on the compression stroke. But I don't know of any way to determine that without extensive exploratory surgery. I would prefer to avoid that route if at all possible. I just want to mow my friggin lawn. :mur:

The manual shows a rocker arm assembly. What is the likelihood that the problem is in the top end? Maybe a loose rocker? I'm running out of ideas. :confused3:

Yes take the valve cover off 4 bolts on that. Then turn by hand and see if the valves are moving up and down......

if they are moving then your cam is in place. Look at the push rods are they both there ? I have seen rods go in the blocks before.

Well somehow I got it working again. I'm not certain what was wrong, but my best guess is that it has to do with the safety mechanism that prevents it from starting unless it's in park. I know for certain it was in park before this whole ordeal began because the starter was initially able to crank the engine. So I figure it must have slipped out of park in the process without me knowing. Just goes to show...sometimes when you expect the worst it can turn out to be a simple solution right under your nose. Picked up some very helpful information here, so my gratitude to those who responded. Thanks all.