JD X300 w/360 hrs - Smoke from exhaust, possibly not running at full power?

[Tiggs]

Last week the X300 was running fine, this week it just didn't seem like it was running right. It "seemed" like there was a miss or something on low idle but when I powered up the motor and engaged the blades it seemed to cut ok but I "felt" that it didn't have the power that it had previously and even though it is windy here today, I could catch a whiff of gasoline periodically. I stopped the mower, and checked the fuel line to make sure there were no leaks. I also checked the dipstick and indicated it was full. I don't have a great nose but it did smell a bit like gasoline but nothing strong. I was a bit worried because I just didn't feel it was running right so I would stop every now and then and let it sit to cool off. I was almost through mowing when it started to puff what looks like a little bit of smoke out of the muffler. My nephew asked that I drain a bit of oil out into a can and he's going to look at it for me tomorrow. The oil isn't very dirty but does have a faint gas smell. I would appreciate your opinions as to what might be happening. If you need more information, I'll try to provide it. I would really appreciate some help. I'm worried that the engine is blowing up or something, which I can't believe because the mower isn't all that old.

Thank you,

Carolyn

 

[thz71]

How many hours are on your mower? What color is the smoke? When was the last time it was serviced?

 

[Tiggs]

thz71, The motor has 360 hours on it. The smoke looked dark grey and the oil was changed early summer last year.

I thought to pull the spark plug and inspect it. There was carbon on the metal washer ring, the threads were a little wet but the plug itself looked clean/medium grey with no buildup. I also ran a cloth around the inside of the muffler. It had a flat black carbon build up (I don't know if that is normal) but was not wet or shiny as if it was blowing oil or gas out of the exhaust. I ran it for about 5 minutes after I pulled and cleaned the plug and did not see any smoke.

I'm going to run out and get a new spark plug in case it is not firing completely. I'm thinking if it was not, it may explain the gas smell. Is it possible that the unburnt gas could leak into the oil?

Thanks,

Carolyn

 

[Retiredcarguy]

I would suggest the following basics:

Oil and filter change
Fuel drained and the filter replaced
New spark plug
New air filter

Probably all long overdue.

 

[Tiggs]

I would suggest the following basics:

Oil and filter change
Fuel drained and the filter replaced
New spark plug
New air filter

Probably all long overdue.

My nephew said he had done it last summer so it wasn't overdue based on the scheduled maintenance plan. We changed all of the above again this morning. The oil was dirty but not exceptionally so and there was no smell of gasoline. When he looked at the gas filter, it appeared very dark with black sediment inside. He also noted that the gasket for the gas cap is missing and he is concerned that it might have failed and fallen into the tank so I guess we are looking at having the tank removed, drained and cleaned out?

 

[BBO]

When he looked at the gas filter, it appeared very dark with black sediment inside.

How does it run with the new gas filter and new plugs?

 

[Tiggs]

How does it run with the new gas filter and new plugs?

It seemed better, no smoke, but I also didn't push it. I am still concerned about what might be in the tank. I'm going to run it more today and keep a very close eye on the gas filter to see if it traps anything.