Anonymous asked in Home & GardenOther - Home & Garden · 3 weeks ago

why would running a 2 cycle engine with 1/3 less oil in it cause the crank case seal to leak, but not do any damage to pistons & rods?

have a 2 stroke leaf blower that i ran for about 30 hours ( a very long time) with 2 cycle fuel that was not mixed properly was around 1/3 less than the 50: 1 mix that it requires. and i didnt realize anything was wrong until the leaf blower started backfiring and stopping running, but then it would still start and run more after.

i noticed that 2 cycle fuel is leaking out of the seal, but i took the muffler off to examine the piston through the exhaust port and i didnt see any scoring on it, and the leaf blower still runs good, good compression, but still after awhile it starts to not run so good. and the crank case seal is still leaking badly

3 Answers

  • 3 weeks ago

    Insufficient oil mix will destroy a 2 cycle engine in a short time.

    The case warps from heat causing a vacuum leak at the case seal and the engine runs lean. That makes these run hotter yet. Time for an overhaul including flat milling the case or replacing.

    • 3 weeks agoReport

      i assume you mean the "Crank case"? what about the cylinder and cylinder head?  is it possible that the crank case seal can just be replaced?  the engine still seems to have good compression and runs good, it just bogs down after awhile at high rpms due to the vacuum leak via the seal

  • 3 weeks ago

    Well friend you have eaten up the piston rings. Your compression is poor it might run but not very well. You're going to have to take the Piston out and put a new ring on the piston. And replace the seal. While you may not have gotten the shaft hot enough to score it all up.

    You got it hot enough to melt the rubber. Now the seal leaks. From your description you apparently got the ring hot enough so that the piston ring is burned. You won't be able to see that. You might as well take the head off put a new piston ring in and replace the seal.

    • 3 weeks agoReport

      what makes you think the ring is eaten up? I again have good compression, it runs good still, it just leaks oil out of the crank shaft seal

  • John
    Lv 4
    3 weeks ago

    Follow the directions with a two stroke engine. You should bought a leaf blower with a four stroke engine.

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