98 MTD B&S 14.5 HP backfire problem

[FlaGator]

New to Forum posted this in "Mowers section" should have been here.
Have developed a problem over the last month after destroying a set of blades by hitting a stump and stopping the lawn tractor dead in its tracks.
The mower would backfire when I shut it off. The next day when i would go to start it, it would take along time cranking before starting.
This morning it would not start at all only continually backfire.
I quit trying to start it and have decided to do the following.
I think I my have messed up the flywheel key hitting the stump, I am going to check the key.
Since it needs service I am also going to change the air filter, spark plug, adjust the valves, and check the coil flywheel spacing.
Hope this will fix my problem.
Any further info would be appreciated.

 

[bertsmobile1]

Sudden stops are the usual cause of a key shear so the timing will be out of sync with the piston movement.
That is consistant with the rest of your problems .

 

[frenchriverco]

Second bertsmobile1. Sounds like a flywheel key shear. This happens when hitting something suddenly, and it also produces a backfire when attempting to start.

 

[StarTech]

I kinda rare for a rider that belt drives the deck to shear a flywheel key but it does happen. I had one to shatter the flywheel around the crankshaft but this guy was constantly hit tree roots.

If this is a OHV 280000 series engine I do a leak down test while the rocker cover so you can check for a blown head gasket as these do have type head gasket that likes to blow.

And there is several possibles that may showed up just because the age of the engine. Leaky carburetor, badly worn intake push rod, and a worn camshaft lobe.

Just have to take it one step at a time and diagnose the various problems. Its like the time when I ran over a stump with my Yard Machines mower. I end with bent blades, broken spindle, and a blown gasket. Then a few weeks later the carburetor started flooding. I took it in stride as it is an old engine.

 

[Tinkerer200]

Welcome from east central Illinois,

Walt Conner