I have been looking for some time now for a used longtail. I have taken a look at a few in my search and always find myself not sure of what exactly to be checking over closely. I typically look at the prop and shaft and overall condition of the motor. Being new to the mud motor world I wanted to see what others typically check out when purchasing used motors.

Check RPM's? For Vibration? Prop? Shaft? Bearing? Etc.

What is it you look for or what is critical to check each time you step in front of a used motor?

Thanks guys!!

Here are a few things:

Badly leaking grease
Shaft wobble (with prop OFF)
HAVE SELLER REMOVE PROP, if it's stuck on and won't come off you got a fight on your hand getting it off and it may mean replacing the shaft and prop.
Engine hours
Engine Compression
Has it been modded? Personally I would never buy someone else's modded engine.

They are very simple in design, not a lot that can't be fixed or replaced tho.

These are good^ before going to look, know what sized prop goes on it... measure the prop and see what condition its in (easy to buy a used motor then have to replace a prop ($$)) If you can turn a wrench they can be easy to work on and replace parts and what not, but don't pay prime bucks for a turd that needs every little part and piece replaced...

Here is a thread from a while back...
viewtopic.php?f=6&t=33285&hilit=+homemade

^ good advice. If the price is right I wouldn't worry too much about the small stuff. ie bushings, u-joint etc. As long as it runs good most everything else is pretty easy.

Thanks guys for the replies! Some great stuff to think about. Just being new to them it's hard to know what really is critical to check and what can be very minor!!