Lawn Mower: YT 3000, 21HP Platium Engine Died Died Today

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  • / Lawn Mower: YT 3000, 21HP Platium Engine Died Died Today
Lawn Mower: Craftsman Model YT3000, Model no. 917-288512 (about 40 hours on engine) Engine is a B. & S. 21 HP, Platinum single cylinder engine,
Engine Model: 3318772371, Type G1, Engine code: 101012ZD

Starting cutting today and after 5 minutes, while cutting, engine backfired through carb-one time, rpm dropped, engine started to blow blue & while smoke. Run for about 15 seconds,
rpm dropped very low and then died. Tried to start, it would turn over but not start, tried started fluid, nothing, but trying to blow starter fluid back out carb. No noise from engine,
when trouble started. By this time is was nearly dark, so I quite for the day.

I have read a lot of problems with these 21 HP engines & the values. I have a year-2006, 17 1/2 B. & S. engine that runs very good, off an older MTD mower. I looked at the wiring harness,
they both look the same with 6 connector sockets pins.

The Question: What do you think is wrong with the 21HP engine-fix it or could I replace it with the 17 1/2HP engine?
 

dfbroxy

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  • / Lawn Mower: YT 3000, 21HP Platium Engine Died Died Today
The engine is worth trying to save. I think it may have a blown head gasket. Here are a few checks to make before you panic.
1. Pull spark plug and use a screwdriver (carefully) to see if piston moves when engine is turned by hand. Check to see if oil is not overfull
2. Pull top engine cover to see if there is a rat nest or extremely dirty.
3. Remove valve cover and check operation of valves, springs, and pushrods.
4. Do a compression test to see if compression is low.

If 1, 2, and 3 are good and 4 is low, then its likely the headgasket.
 
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  • / Lawn Mower: YT 3000, 21HP Platium Engine Died Died Today
PROBLEM SOLVED! LOOSE SPARK PLUG, LOOSING COMPRESSION

Thanks for the interest and suggestions. First thing I checked was the compression and found the problem.
Started to remove the spark plug & it screwed out with just the socket & extension only, with no ratchet attached. The cylinder was loaded with gas.
I turned engine over 8-10 times to blow out the gas. No gas found in the oil. Put the spark plug back in it, tighten it down properly and it cranked right up with no issues.
Now runs better than it has ever run, since I purchased it, new. I had never had the plug out so I guess is was not tighten when it was installed at the factory.
I figure it was low compression due to leaking out around the plug caused the engine to load up on unburnt gas and flooded it out. It has run somewhat
rough ever since I purchased it, new, and had worked on the carburetor, twice, until the issue with the spark plug was solved, today.
Checked the head gasket, no signs of any leakage on it.

Never dreamed a simple problem could cause some much trouble? Happy camper now, running perfect! Those new engines cost as much as the lawnmower.

Sorry for the double post in the original heading. It was a long hard day for me.
 
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