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MTD 42 inch 2001 model, 14.5 hp motor threw a rod today and cracked the block. Actually this is a 12.5 motor on there now. Original motor's starter holes were stripped out so changed to the 12.5 one. It was leaking oil some and had to add oil everytime I go to cut. I noticed the other day it started vibrating some, the engine. Checked the bolts and they were fine. Motor still vibrated some and was loud even with muffler on. This morning started it up and same thing then finally it cut off , wouldnt start back, and I saw the cracks.

I want to get a used motor to put on it and I looked at some today. This guy had one where the carburetor cover, the air filter cover actually, wasn't on it and you could see where some water was down inside it. Would it be a good idea to buy that motor? 75 bucks.......

Give me some what to look for, check out as far as looking for a motor. I know the obvious visual stuff but without hearing it run , I know there are some specifics to check for. The guy was working on getting it cranked for me but I didnt have time today to wait on him
 

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I would never buy a used motor without hearing run with the muffler installed. I would drain oil and check that there was nothing funny there after running itand warming it up.
 

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I have 2, 12.5s here that I got for (almost) nothing; I just finished totally rebuilding one of them and with a cylinder overbore and a crank cut, along with the required oversized piston and undersized rod, I have ~$245 tied up in the one I've done so far; I have a machine here to mount it to and may have another needing an engine sitting here as of tomorrow. meaning I will probably go thru that one and rebuild as needed, too; probably not "worth it" but much cheaper than new engines, less "chancey" than an unknown-hour, unknown maint. supposedly good engine that may not really BE good.

do you still have the 14.5? You could fix those starter mount bolt hole threads, with heli coils. and put that engine back on.
 

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Discussion Starter #4
I have 2, 12.5s here that I got for (almost) nothing; I just finished totally rebuilding one of them and with a cylinder overbore and a crank cut, along with the required oversized piston and undersized rod, I have ~$245 tied up in the one I've done so far; I have a machine here to mount it to and may have another needing an engine sitting here as of tomorrow. meaning I will probably go thru that one and rebuild as needed, too; probably not "worth it" but much cheaper than new engines, less "chancey" than an unknown-hour, unknown maint. supposedly good engine that may not really BE good.

do you still have the 14.5? You could fix those starter mount bolt hole threads, with heli coils. and put that engine back on.
my uncle has it I believe. Never used heli coils so i'm sure I would take it to a shop. Whats involved in that process? And do u want to see the one you worked on?
 

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Heli-coils allow you to drill out the original hole to a specific diameter, thread it with their tool, and then install a cylinder that is threaded on the outside to fit the threads just cut, and threaded on the inside to the original hold diameter and thread spec. I just saw some kits at Advance auto parts to perform the same function, but they were not branded with the Heli-coil name. I think they expected the customer to cut the larger threads with their own tap and die set. I didn't examine the package as closely as I would if I were in the market.
For that matter, if your starter would allow larger bolts, you could drill and tap the existing hole to the next size up.
tom
 

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usually they come with the special tap needed to thread the hole oversized for the insert to thread into; unless you get "refills" which would be just a package of the inserts; and as far as I know, the thread that the insert threads "into" is a special non standard thread size that is specific to those inserts. they do tell what drill size is needed for them, in the package.
as far as doing it yourself/taking it in; unless the shop is next door it'll probably take longer to drive to the shop than the process takes!
those should be a 5/16-18 which is a VERY common thread size; a small machine shop or even a mechanic at your local garage may have a Heli Coil set for that size in his tool chest! it don't "have to" be a small engine shop; in fact I could see them more likely to say "unfixable" and try to sell you a shortblock. just cary the engine in w/o the starter in place so they can see what holes need rethreaded;
the only possible issue is if they are "blind" holes (dont go all the way thru) and whoever fixes it drills them thru.... be careful about that.
 

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Discussion Starter #7
usually they come with the special tap needed to thread the hole oversized for the insert to thread into; unless you get "refills" which would be just a package of the inserts; and as far as I know, the thread that the insert threads "into" is a special non standard thread size that is specific to those inserts. they do tell what drill size is needed for them, in the package.
as far as doing it yourself/taking it in; unless the shop is next door it'll probably take longer to drive to the shop than the process takes!
those should be a 5/16-18 which is a VERY common thread size; a small machine shop or even a mechanic at your local garage may have a Heli Coil set for that size in his tool chest! it don't "have to" be a small engine shop; in fact I could see them more likely to say "unfixable" and try to sell you a shortblock. just cary the engine in w/o the starter in place so they can see what holes need rethreaded;
the only possible issue is if they are "blind" holes (dont go all the way thru) and whoever fixes it drills them thru.... be careful about that.
talked to my uncle this morning and he said because its aluminum it might not work so good. I was gona take to a machine shop though anyway maybe
 

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Heli coils work fine in aluminum as well as copper. We used to use them in copper because the threads would last longer during repeated use.
 

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talked to my uncle this morning and he said because its aluminum it might not work so good. I was gona take to a machine shop though anyway maybe
they work just fine in aluminum; actually being stronger than the original threads, since the threads the Heli coil threeads into are "deeper" than the originals so have more "bite"; I usually set them in with Loctite to be sure they don't unthread from the base metal.
that and now you have steel threads for the bolt to go into.
 

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Heli coils are very expensive if you buy a kit to do 3 holes,and many aircraft engines come from the factory with heli coils in aluminim parts they last longer than aluminum threads,
 
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