Welcome to MTF! Maybe a few pictures of how you ran put the new engine in and tied it up to the transmission would help.

 

OK

 

 

 

So looks like you are driving the shaft (I'm assuming proper rotation) is the hydrostatic control on the dash moving the linkages to the transmission? Also, is the hydrostatic release lever/knob engaged?

 

If the "hydrostatic release knob" is the knob near the seat that says to rotate one way to operate and the other to push manually, then yes, it is set for operation.

The linkages from the lever are all working.

"Assuming proper rotation" might be assuming too much. The engine turns the driveshaft freely and smoothly, but I don't know if I was supposed to check anything else??

 

Did you remove any of the hydraulic lines at all? I'd be tempted to raise the rear end off the ground and then operate the hydro control to see if the wheels will turn. Might just be some air in the line and that should bleed it.

 

I didn't touch the hydraulics except to disconnect the blade from the front.

 

OK, I'd still put the rear up so neither wheel is touching the ground then start it and try the hydro control. If any air entered the system that should bleed it

 

I did put the rear up and tried that, but it didn't work.

I did figure out the problem -- the motor I installed rotates in the opposite direction of the original motor.

Now the question is if I should try again with a different motor, or if I broke things with my mistake.

 

I was wondering about the rotation, couldn't see it in your pictures. Find some way to spin the shaft the correct way and see if things work. If you only did it for a short period you may be OK. But, it can harm the pump.

 

Odds are the pump is okay. Some people have connected a heavy duty electric drill to turn the transmission input shaft for testing.
Engines basically all turn the same direction, so it's not like you can find one that turns the other way. What you can do is turn the engine you have the other way. You would need a drive adapter made for your engine that bolts to the other end.

 

1969140 nailed it. I have a honda 630 mounted on my 318. The big long keyed shaft goes out the front for the PTO. The flywheel side of the engine faces back. I have an adapter that bolts onto the flywheel. I do not have a pull cord like you, so that would need to go. Is that a starter motor on the side? If so, you still have hope.

There are adapters you can buy. Do a google search. Then double check with the vendor that it will fit your engine and shaft.

 

Got it figured out. I did rotate the engine 180. I took the stub shaft off my original motor. I removed the manual pull start from the predator engine and Frankensteined the shaft onto the steel cylinder that the pull start connected to. A little tinkering and it works great.

 

Just as well. Who likes pull starting those things...