Small Engines (Lawn Mowers, etc.): Blew my engine?, engine bolts, riding lawnmower

Question
I have decided to buy a new engine.... someone on ebay is selling one and he's willing to negotiate a price lower that $400..... I don't know what an impact gun is... do you mean one of those drills thats used for making holes in concrete? Is this engine change something you think I can do or do I need alot of muscle... haven't looked at the bolts yet-from new england and it dark at 5pm... have to wait until the weekend... what about getting a short block? would that be cheaper? Thanks again for you help!!!!

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Followup To
Question -
I have a 5 year old 13.5hp Craftsman B/S engine in my riding lawnmower. As I was using it yesterday I heard a loud clunk and the mower stopped and I could not restart it. I opened the hood and looked for anything obvious and I found what looked like pieces of the engine housing broken off and what looked like a small 1" black disc protruding from where the pieces were. I cheked the oil from the drain and there was hardley any oil in it.... duhhhh... I'm an engineer and should know better but anyway, shall I assume it's one of the valve thingys which has broken a hole in the block and I've cooked the engine? I have found an engine replacement for $400.... there are 3 bolts hlding the engine on the mower.... other that the 3 bolts what else has to be removed to replace the engine? Also... is there somplace to by a rebuilt engine? thanks for the help...

Answer -
You will have to remove the engine stack pulley and transfer it to the new engine.  An impact gun makes this task very easy.  Are there 4 engine bolts?

I'd recommend getting a replacement engine.  I don't know of anyone or any company that sells re-built small engines.  High labor rates and cheaper manufacturing processes have virtually eliminated small engine rebuilding.

Let me know what you decide to do.
Eric

Answer
An impact gun is what most tire shops use to remove lug nuts.  Most guns are air powered but you can get electric powered impact guns.

A short-block may be a little cheaper but it requires a lot more time to remove and transfer all the old engine parts to the new short-block.  You will also need a torque wrench and feeler gauges along with a basic set of hand tools to tranfer the parts.

Does this help?
Eric