7.75 ftlb Briggs and Stratton - Rocker Arms stuck?

[itsgalf]

I picked up a nice Troybilt pushmower with a 7.75ftlb Professional B&S Engine on it. Model: 11P902-0693-B1

The carburetor was heavily gunked up so I replaced it. Went to see if it would start up and...no resistance. Turns way too easily. Checked the compression - 0 psi
I opened up the OHV Valve cover and the push rods and rockers don't move as I rotate the flywheel. One of them is stuck engaging the exhaust valve so it's always open (or maybe it was the intake...I forgot already).

I thought maybe the flywheel key was sheared, but it's not. The blade turns along with the flywheel.

I'm going to have to break it down further when I get the chance. Anyone with prior experiences with ideas of what this might be? Something happened with the cam shaft?

 

[itsgalf]

Well got into the crankcase.

Camshaft looks good, push rods good, tappets good.
Plastic Timing gear on the crankshaft - the key portion of it sheared so the timing gear wasn't actually being driven by the crankshaft.
Thankfully it looks like the replacement timing gear is actually made of steel.



Hopefully this is the only thing that's wrong with it.

 

[itsgalf]

Hmm can someone tell me what this part is? I can't seem to see it in the parts breakdowns.


Circled in Red
It's the very thin spacer piece that goes on crankcase cover. I'm not sure what it is and can't seem to find it for an old engine I had stored in a shed disassembled.

 

[Scrubcadet10]

That is a thrust washer( commonly referred to as a Shim), it controls the crankshaft endplay, which is the side to side movement of The crank, usually around 5-10 thousandths of an inch.

 

[itsgalf]

It doesn't show up in the parts breakdown for the engine. I assumed that all these Briggs engines had one, but does that mean this one does not need it? (I can't remember from way back when I took it apart)

 

[Scrubcadet10]

I have yet to see a small engine without a crank shim, although some use different thickness gaskets to set end play.It might be a part that is code date specific, but it should be listed anyway.
I'd say leave it there.