Price a new rider and you will be inclined to replace the engine on what you have. Just my humble opinion.
I have purchased a number of good used engines on Ebay. You have to make sure you ask a lot of questions. If they cannot provide intelligent answers, walk away.
You will need to know the numbers on the engine label to get a match. These engines were used on many different rider models and configured accordingly.
Another source is repower.com
#3
ILENGINE
A replacement engine will be in the $1K range more or less. A new rider will start at $2K and go up, so have to decide from their.
Have you considered repairing the existing engine? Do you know why it seized in the 1st place? Low oil perhaps? If it's just a matter of the rod seized to the crank, and the piston/rings/cylinder are OK, the repair is pretty basic. Get the rod cap off and double check if piston is free. The important thing with this repair is to remove the aluminum deposition from the crank. Do not skip this step! This is best done with muriatic acid but you need to careful for obvious reasons. Replace the rod. Crank should be just fine. Also need to check for a blown head gasket which is a common cause of the excessive oil consumption which can go unnoticed until a catastrophic failure.
Just one avenue to consider if your cool with a complete teardown! Cheaper than a new engine! Good luck.
Forgot to mention, if it is a rod replacement, when you have the piston out, pull the rings and check ring gaps. Since you have it apart, ring replacement is a no brainer if needed!
The cost of engine plus labor to remove and replace is cost prohibitive. Buy a good used riding mower for half the cost of engine and labor. Nobody ever repowers their mower when the engine goes bad.
I would agree that if you are having to pay someone to do all the work, it is likely not worth it. However, it can be very beneficial and satisfying if you have the capabilities and tools(nothing fancy) to do the work yourself.
I bought a JD D105 with a blown 17.5 B&S in otherwise mint condition with low hours for $250. Pulled the engine which took less than 30 mins and 30 more mins of opening it up revealed it was toast. Purchased a brand new B&S 17.5 replacement for under $600 and installed it in 45 mins. Runs like a champ and it looks like new. So for a little over $800, I've got a great tractor. In my area of NE OH, used tractors of this size and condition rarely sell for less than $1200, which is about half of the new price for a similar unit. (I can reduce my cost even more by selling off parts from the bad engine like the starter, fuel pump, carb, head, etc. as the OP contemplated in their original post)
So in summary, I agree that if you have to write a check, used units of all sizes and conditions are out there. However, with a modicum of interest, ability, and a modest set of tools, it's a great learning opportunity. Enjoy!
ps: I'm sure there a models out there that are a PITA to disassemble so your mileage may vary! I have a fair amount of experience working on these which is why my times are fairly quick and I thoroughly enjoy the work.
