Siezed engine

charlesv842

LawnSite Member
Location
Austin, TX
So my buddy thought he could put a two stroke spark plug into a four stroke lawn mower. The guy brings it back because it blew up on him. I'm pretty sure it's siezed and that the plug is why.

My question is why a colder running plug would do it. Colder plugs are for the hotter running temperatures of a two stroke. So why would it overheat a four stroke?
 

redmax fan

LawnSite Silver Member
like slowleak said our mechanic long time ago warned me to watch for putting a longer / too long plug into equipment because it'll hit piston

even when he buys new plugs that box says are a match he puts them side by side with old one to make sure new one isnt longer by mistake
 

dboyd351

LawnSite Bronze Member
Location
Cape Charles, VA
This one should be good!
There aren't 2 stroke and 4 stroke spark plugs. There are short reach and long reach plugs. Putting a long reach plug in an engine designed for a short reach plug might cause the plug to hit the piston and hole it, but if it did, you would have no compression, not a siezed engine.
 

BIG NICKY

LawnSite Member
Location
crystal lake il
This one should be good!
There aren't 2 stroke and 4 stroke spark plugs. There are short reach and long reach plugs. Putting a long reach plug in an engine designed for a short reach plug might cause the plug to hit the piston and hole it, but if it did, you would have no compression, not a siezed engine.

however if the piston is just resting on the plug then it would act just like a seized engine. but without knowing the details of what you have done to remedy the problem it very well could be seized but not because of the wrong plug
 

unkownfl

LawnSite Platinum Member
There is short reach and long reach plugs. This would cause an immediate engine failure if the plug was to long not an over the time issue.

The OP is correct using the wrong heat range of plug could cause the engine to overheat. Usually if the operator wasn't paying attention or had ear muffs on they wouldn't notice the detonation with a hotter plug than what is called for. A 2 cycle plug is usually colder than a 4 stroke from my experience. I shouldn't say 2 stroke vs 4 stroke plug as they could be used interchangeable depending on the engine I'm sure. I seriously doubt a plug caused an engine failure though unless the actual plug seized the engine physically.
 

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