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Hello I have a strange problem, Today I start my mower with no problem and cut my front yard, I cut off my mower and it WILL NOT start, in fact the motor is turning over very fast now. so this is what I have checked:

I pulled off the valve cover and check the push rods and made sure they were both adjusted fine, turn the engine by hand to see if both valves were moving, adjusted both the valves.

Turn the plug out and made sure the piston was going up and down, checked the spark on the plug and it was getting fire..???


I just don't know whatever to check?? Any suggestion on what could be wrong with this engine?

Post all numbers from engine data plate, everything. First check oil level on dipstick, make sure it's on full mark, fresh gas in tank, check gas & air filters for replacement. Check fuse between ignition switch & solenoid, lastly raise seat & check seat safety switch & wiring for being pinched.

mechanic mark said:

Post all numbers from engine data plate, everything. First check oil level on dipstick, make sure it's on full mark, fresh gas in tank, check gas & air filters for replacement. Check fuse between ignition switch & solenoid, lastly raise seat & check seat safety switch & wiring for being pinched.

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Thanks but it is getting fire, that shows it is not a switch, I am thinking it is a blown head gaskins

Blown head gasket could be a possible problem, but I am thinking more along the line of dropped valve seat in the head. When you adjusted the valves, did one seem way out of adjustment.

No both seems to be fine, but I went on and adjusted them anyway, if it was drop valve in the head when I turn the motor over both open and closed.. they could both work it if one had dropped in the head right?

The valves would still open and close if the seats came out, but wouldn't seal. Usually when this happens the push rod will drop out or have excess slack. From your description it sounds like a sudden lose of compression. May need to check compression and see what it is. I suspect close to 0. Blown head gasket on those single OHV engines will normally run for some time when the head gasket is going back, but will either smoke severely or blow oil out places it should come from like past the dipstick seal.

Well what you saying makes sense, yes it has been smoking for a while, I plan tomorrow to pull off the head and check the head gasket, and check the valves to see if they are seating....hopefully it just the gasket, and the one the valves has gummed up and cleaning will fix it.

ILENGINE said:

The valves would still open and close if the seats came out, but wouldn't seal. Usually when this happens the push rod will drop out or have excess slack. From your description it sounds like a sudden lose of compression. May need to check compression and see what it is. I suspect close to 0. Blown head gasket on those single OHV engines will normally run for some time when the head gasket is going back, but will either smoke severely or blow oil out places it should come from like past the dipstick seal.

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If that what wrong with it, the only fix would be to replace the head?

I have reinstalled the seats back in their recess area and then peened around the edge to hold them in place.

In other words just take out the valves clean or replace and make sure they are seating right..

Might as well clean up the valves while you have the head off.

Well do... and thanks

Ok today I pull off the head, and the exhaust valve had dropped, and it was not seating so if I can not fix it, I just going to have to replace the head.

I suspected that is what happened when you said that it turned over faster than it use to. Don't feel bad though, I had one come in the shop friday on a Snapper that did the same thing on on older flat head. Also pulled the engine on a Bushhog ZTR that has 1/4" missing from the edge of one exhaust valve, and the other exhaust valve is burnt. Will be replacing on valve and the other head for reasons not including the valve.

Well I just ordered another head, the engine looked very clean, the piston looked like new... so when the head comes in I will be good to go..

Update my head came in, and I installed it and the motor is running great, it feels like it has more power and the motor will accelerate faster...THANKS AGAIN FOR ALL YOUR HELP..