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So I ended up with an LB 8237 Self Propelled from a neighbors front yard a few years ago, and it seemed to run ok for about a year, but recently started putting out white smoke and having some issues running.

I disassembled the mower and engine, and found it caked with soot and carbon. Put it back together and she runs better with a new plug (nearly no smoke) but it still has some issues running, and I wondered if you guys had any ideas. Currently it runs great while it is mowing, but as soon as I dis-engage the self-propelled drive it spins down, then picks right back up. It doesn't seem to be much of an issue as it perks right back up after about a second, but I can't imagine that this is it's correct behavior.

Anyway, I've torn her down for a second time (after mowing my lawn) and found some areas of concern.

1 - There wasn't any gasket between the two case halves - should I be using something there for a better seal, or will the aluminum seal itself?

2 - there are some dark areas on the piston that won't come off. I cleaned it with laquer thinner, and then a light rub with 2000 grit sandpaper. Still won't come off - is this an issue?

3 - there is a little bit of play at the crank end of the connecting rod. This is side-to-side play (I can tilt the rod ever so slightly on the crank). Is this normal, or should I be replacing bearings there?

4 - there is a little bit of play at the piston end of the connecting rod. I can also tilt the piston ever so slightly on the wrist pin.

5 - there are some scuff marks in the bearing seats in the casing. The bearings both spin freely, so I can't imagine that this is from the bearings spinning (especially with those keys in them) but it does concern me a little bit. Should I be concerned?

6 - What parts would you recommend replacing in a standard rebuild? I've never done a rebuild, but replacing 20-30 dollars worth of parts while I've got the whole thing torn down seems like a great idea, even though I think I fixed the smoke problem by cleaning out all of the carbon buildup.

7 - what kind of oil/grease should I be putting back in the transfer case for the self-propelled PTO?










 

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5K Poster!!!
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The piston/crank and block all look good but yes, you do need to use anerobic gasket maker between the cases. Look for it in very small tubes from locktite and I believe permatex makes it also.

BTW, I'm in Ames all the time:trink39: :Welcome1:
 

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Decesaed (R.I.P.)
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Everything looks pretty good and sounds normal. You'll always have that type of play in the those bearings when they're not assembled in the engine. It's the direct side play when assembled that you want to look at. Most of the time bearing don't need replaced on these engines.

Piston looks good just don't want it scored up real bad.

A standard rebuild for me is rings, seals, gaskets, a good clean up and cylinder honing.

Type A grease is called for in the transmission. The gear set in the engine gets lubed via the oil in the fuel.
 

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The piston/crank and block all look good but yes, you do need to use anerobic gasket maker between the cases. Look for it in very small tubes from locktite and I believe permatex makes it also.

BTW, I'm in Ames all the time:trink39: :Welcome1:
Where can one find the anerobic gasket maker? Autozone, Pep Boys, Advance Auto-is there a certain color made that's best. I am about to rebuild my Duraforce.
 

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LAWN-BOY-AHOLIC
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1,349 Posts
GTP, all those places should have it, if not Napa does for sure. You can buy F series engine rebuild kits off ebay for around $40. Do make sure you install new crank seals when putting it back together. You engine internals looks good to me, I have rebuilt Lawn-boys with shallow scratched cylinders from piston pin retaining clips that came loose while running and they ran fine.
 

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Castor Freak
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Welcome to the forum! Awesome pictures and detail on your first post, you'll fit in great here.
 

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Lawn-Boy fan
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Welcome to MTF! That looks like a good project, those mowers are so easy and enjoyable to mow with too. Glad you're fixing it up.
 
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