Push mower keeps stopping

[Mower King]

I give up, ignition coil installed and it only want 8 minutes. If it needs a valve adjustment I'll have to take it on somewhere and after that money and all the parts I've put into it I might as well just get a new one. I'll sell this one to someone that knows how to fix it or wants it for parts. So frustrating. Thank you all for your suggestions.

Sometimes, if the repair gets beyond the mowers worth or a repair you can't do yourself....it comes to that.

 

[Scrubcadet10]

Over Head valve push mower, valve adjustment should be pretty simple, plenty of videos on the interscreen, any good repair man that runs a business will/should know how to adjust valves....
I remember seeing the clearances for the MTD OHV engine.... i think it was .010" Intake and .015" exhaust... that is if my remembory is right
Is it A MTD brand engine or a Briggs and stratton?

 

[slomo]

Hi, I have a MTD 21" self-propelled 139cc OHV push mower. It runs strong for 10 minutes or so then stops. If I wait 15-30 minutes I can usually get the last 10 minutes of mowing done. I have such a small yard and this is really frustrating. I have replaced the spark plug, changed the oil, air filter, fuel filter and fuel line. I've also pulled out the carburetor and it looks clean. I'm imagining that it's overheating but I don't know what else to do to help with that. Any suggestions would be appreciated.

Now you have two good spark plugs.

slomo

 

[slomo]

It sputters for a few seconds then dies.

Sounds like it is starving for fuel.

slomo

 

[slomo]

Okay, so new gas cap didn't change anything. Mowed for 10 minutes then sputtered and died. Is the ignition coil my last option?

Now you have two gas caps.

slomo

 

[slomo]

Sounds like it needs a valve adjustment.

Not from what I've seen in the past. Hard or no starting at all tells me valves. Running for several minutes, then sputtering, is not valves. Out of spec valve clearance should cause issues at all times. 8 minutes then it sputters, she is thirsty.

slomo

 

[slomo]

I give up, ignition coil installed and it only want 8 minutes. If it needs a valve adjustment I'll have to take it on somewhere and after that money and all the parts I've put into it I might as well just get a new one. I'll sell this one to someone that knows how to fix it or wants it for parts. So frustrating. Thank you all for your suggestions.

So after all those parts that are new, clean the carb or buy another one. Did I say that?

slomo

 

[Fish]

Not from what I've seen in the past. Hard or no starting at all tells me valves. Running for several minutes, then sputtering, is not valves. Out of spec valve clearance should cause issues at all times. 8 minutes then it sputters, she is thirsty.

slomo

If the valves are too tight, it will start and run until gets warm, then the valves can no longer seal.

 

[Fish]

Valve gap is too great, then the compression release will not function correctly.

 

[slomo]

Valve gap is too great, then the compression release will not function correctly.

This wasn't stated by the OP as an issue.

slomo