Engine lets out a puff of smoke but doesn't even sputter when attempting to start

[jetpackjbd]

Hi, my 2002 riding mower has a 13 horsepower B&S engine. It's been running fine and starting instantly. I shut it off and went to turn it on a minute later, and it refused to do anything. It wouldn't even spin. After turning it with a torque wrench for a bit, it became loose and spun easily. The oil was mostly clear and was at the full mark. Replaced the fuel filter and spark plug and got it to give off a single puff of smoke, but that was it. Even with starting fluid, nothing changed. The battery is under a year old and is at normal voltage. Really hoping the engine isn't toast...

 

[bertsmobile1]

Take the rocker cover off & check that all of the push rods are there
When the valve lash gets really sloppy the rocker can fall off then the rod fall into the engine
Some times they just sit there & some times they lock up the engine
If it has fallen in & gotten chewed up you will have to split the engine to find all of the little bits as a very small piece of debris can jamb the governor then it is zoooom BANG

 

[jetpackjbd]

Take the rocker cover off & check that all of the push rods are there
When the valve lash gets really sloppy the rocker can fall off then the rod fall into the engine
Some times they just sit there & some times they lock up the engine
If it has fallen in & gotten chewed up you will have to split the engine to find all of the little bits as a very small piece of debris can jamb the governor then it is zoooom BANG

Will do soon, hoping this isn't the case. I assume if it is, then it's probably time to get a new mower.

 

[jetpackjbd]

Take the rocker cover off & check that all of the push rods are there
When the valve lash gets really sloppy the rocker can fall off then the rod fall into the engine
Some times they just sit there & some times they lock up the engine
If it has fallen in & gotten chewed up you will have to split the engine to find all of the little bits as a very small piece of debris can jamb the governor then it is zoooom BANG

Just remembered the engine is non-ohv, so it has no pushrods, right?

 

[sgkent]

try it with the spark plug(s) out to see if it spins.

 

[bertsmobile1]

Sounds like the engine is toast
Had you been driving along a slope just before you stopped ?
To check that it is in fact an engine problem, pull both belts from the engine pulley
A jambed up belt can slow the cranking down just enough to prevent the engine from starting

 

[jetpackjbd]

try it with the spark plug(s) out to see if it spins.

I already got it spinning freely, sorry if I hadn't made that clear in the original post

 

[jetpackjbd]

Sounds like the engine is toast
Had you been driving along a slope just before you stopped ?
To check that it is in fact an engine problem, pull both belts from the engine pulley
A jambed up belt can slow the cranking down just enough to prevent the engine from starting

I was driving up a mild slope, but it was far under 15 degrees. I've made sure to clean the deck and belt area every other week, and made sure to do so before attempting to service. I can freely turn the belt by hand and the engine by hand, but I can try removing the belt if you think that'll help. I should mention the reason I turned the engine off originally was that I couldn't go into reverse for whatever reason, so it's likely there's some belt issue

 

[bertsmobile1]

It is a case of elimination
By removing the belts we eliminate the mower putting a drag on the engine
When running along a slope it is easy to have the oil pick up in the air so the oil pump is pumping foam or just air
The top bushing area has a small dam of oil and if it is not kept full then the crankshaft can sieze in the crankcase
Or the starter motor can jamb which normally releases by rotating the flywheel backwards.
A 2002 model is well past its use by date but we are here to fix things if that is at all possible
Usually side valve engines loose valve lash on the exhaust because the valve seat burns away
All side valve engines do this and when it gets chronic the exhaust valve no longer seals
It is a PIA on side bangers to check because the valve chest is behind the carburettor.
In the workshop I have both a bore-o-scope & a leak down tester to check for this .

If the valves can close & the timing is good then the engine will fire when you put fuel down the plug hole
If it does not fire then either the valves are not sealing or the flywheel has spun on the crankshaft so the spark is out of time
or the piston is no longer going up & down.( check with a pencil poked down the plug hole .)


If the engine had a temporary seizure & you forced it free by turning the flywheel then there is a good chance the timing key broke or the con rod broke

So try what has been sugested and come back

 

[jetpackjbd]

It is a case of elimination
By removing the belts we eliminate the mower putting a drag on the engine
When running along a slope it is easy to have the oil pick up in the air so the oil pump is pumping foam or just air
The top bushing area has a small dam of oil and if it is not kept full then the crankshaft can sieze in the crankcase
Or the starter motor can jamb which normally releases by rotating the flywheel backwards.
A 2002 model is well past its use by date but we are here to fix things if that is at all possible
Usually side valve engines loose valve lash on the exhaust because the valve seat burns away
All side valve engines do this and when it gets chronic the exhaust valve no longer seals
It is a PIA on side bangers to check because the valve chest is behind the carburettor.
In the workshop I have both a bore-o-scope & a leak down tester to check for this .

If the valves can close & the timing is good then the engine will fire when you put fuel down the plug hole
If it does not fire then either the valves are not sealing or the flywheel has spun on the crankshaft so the spark is out of time
or the piston is no longer going up & down.( check with a pencil poked down the plug hole .)


If the engine had a temporary seizure & you forced it free by turning the flywheel then there is a good chance the timing key broke or the con rod broke

So try what has been sugested and come back

-It can't hurt removing the belt, I'll try that from now on
-The starter motor is good: it spins, goes up when starting, and goes back down when off.
-Unsure of the valve condition, will check
-I think the con rod is fine, I can feel some compression and see the piston moving up and down.
-The timing key/magnet is quite rusty but is still magnetic and hasn't broken. It's possible it became offset though, however it doesn't seem to fire at all, forget misfiring.

In a bit I'll try removing the belt, putting fuel directly in the spark plug hole, then checking the valves.

I've also seen people have a similar starting issue, which is caused by safety switches which prevent the engine starting if the deck is down for example. The switches can get stuck and make it think it's still down when it's up. I've tried starting it while one of the switches is disconnected, no luck, but there may be other switches I'm unaware of.