Mowing lawn this morning, hit a dense patch of grass and the engine sounded
like it would stall so I raised the mower to relieve mulch. A loud pop and
flash, similar to an M-80 (maybe not quite as loud) and a blue flash out the
right side of the mower. (Muffler is on the left, so I knew it wasn't a
A friend suggested the "finger over the spark plug hole" compression test which
it appears to have failed: no vacuum or compression in the chamber.
The question...How much would a valve repair be if I take it back to Sears?
...To anyone else? (This is a 5 year old Craftsman 22" 6.75hp).
<< since its 5 yrs old is it worth fixing. >><p>I doubt it's a rod or
piston...there would be grinding and other messy noises, which there are none
And I may replace it. It just depends on how much it might cost to fix. Anyone
know how much a blown valve might cost to repair on a 6.75hp engine?
Ive blown a hole in a piston, cracked rings, and only had smoke, no
grinding, no noise . No one can say how much to repair as even you
dont know the problem or extent of damage. Or extent of debris in the
This type of damage comes from wear, wear from not maintaining the
mower with good oil or overworking it. Is it a temsumseh, they are the
bottom of the barrel, rarely worth rebuilding.
Valves dont take the brunt of wear on Temsumeh or in a load up.
They have crap bearing and oiling design.
Sears has honda powered mowers now, cheap. go get a 20 yr honda , use
better oil, change your oil more often and dont beat yor machine and
expect it to last.
Well I never heard of a "blown valve" doing as you described and I think you
can forget that. I 'might' be a blown head gasket which wouldn't be much. If
it has thrown a rod resulting in the described action, it should be obvious
by looking at the side of the engine. If it threw a rod and didn't bust the
side of the engine, you would not have seen anything out that side when it
occurred, if there is a hole in the block, throw the engine away. There
would not necessarily be any other noise associated with throwing a rod.
You should be able to stick a dowel or long rod in the spark plug hole and
tell if the piston is going up and down when you turn the engine by hand.
This will tell you if it has thrown a rod absent a hole in side of block.
This same thing happened to the mower of a friend of mine. No compression -
valve not moving. We opened the case and noticed that the plastic cam gear
had broken in half. Got the $20 replacement gear from sears, put it back
together, and it ran like a champ.
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