149 dying out

[bhoffman1973]

I mow about 2 acres with my 149 and a 50A mower deck. Last week, after about 30 min of mowing, it began laboring, eventually began to pop and sputter, and would die out. I could disengage the mower deck and slow the throttle down and it would clear itself up to run smoothly but I couldn't run it under load.
I reset the carb (Walbro) to factory settings and made sure everything is running smoothly with no load. Yesterday, I made another attempt but after about 2 or 3 min of running fine with the mower deck engaged, it began the same thing and eventually choked itself out. Again, it will clear itself up and run just fine under no load. The mower deck spins easily by hand.
I posed this question in a forum on FB and was told to check the coil for overheating or possibly head gasket. Yesterday, the coil was warm but certainly not hot (again, it had only run for a few min). Any thoughts or ideas? Thank you! My grass continues to grow

 

[digger]

I mow about 2 acres with my 149 and a 50A mower deck. Last week, after about 30 min of mowing, it began laboring, eventually began to pop and sputter, and would die out. I could disengage the mower deck and slow the throttle down and it would clear itself up to run smoothly but I couldn't run it under load.
I reset the carb (Walbro) to factory settings and made sure everything is running smoothly with no load. Yesterday, I made another attempt but after about 2 or 3 min of running fine with the mower deck engaged, it began the same thing and eventually choked itself out. Again, it will clear itself up and run just fine under no load. The mower deck spins easily by hand.
I posed this question in a forum on FB and was told to check the coil for overheating or possibly head gasket. Yesterday, the coil was warm but certainly not hot (again, it had only run for a few min). Any thoughts or ideas? Thank you! My grass continues to grow

Change the condenser. It's that or a sticking valve.

 

[kmcconaughey]

I second Digger's thought that it's the condenser. A failing condenser will certainly cause those symptoms. BTDT

 

[btaner]

After sitting in my shed for a short time, mice build a nest under the tins, runs real hot and soon runs bad.

 

[Ken Black]

head gasket...

as btaner said... maybe mice got under tins and built a condo.... it over heats and head lifts. when cools down head shrinks ... runs fine for a few mins then bang pop tinny sounds..

 

[mtener]

Mice nest or even debris in the fins of the head can cause overheating. Also make sure all of the tin shrouds are still in place around the head. Airflow from flywheel is directed through the fins by those shrouds.

 

[Greg Riutzel]

Nests and air blockage would cause a stink, let alone the smell of a hot engine head.

 

[kweimann]

Sticking exhaust valve, common on the K321

 

[jkoenig]

ticking exhaust valve, common on the K321

Does Marvel Mystery Oil help fight this? It was recommended to me here a long time ago to always add some to Cub Cadet gasoline. I know it's primarily for the valve seats, but it couldn't hurt the valve stems and guides, right?

Note to self: add sticking valve to list of possible causes of warmed up run issues on my 782. Not sure if KTs were as prone to this, though.

 

[kphill]

My 102 exaust valve would hang up every once in a while and lose power and shut down.. I would wait about 20 minutes and it would start up and run fine.. I would run MMO in the gas and it helped but it would still do it.. Finally I pulled the motor and took it to our local CC dealer who was good with engines.. I had them press a new exaust valve guide in and replace the exaust valve and it has been fine ever since..

 

[Lee Arnold]

my first job was at a place that sold JD tractors before I started -we had a couple for moving boats and mowing -I learned all about the stuck exhaust valves! engine would die then when it cooled the exhaust valve woud snap closed -I still have the adjustable reamer to clean the guides! (that was 45 years ago!

 

[manthony]

Exhaust valve lash too small. When it heats up and grows longer, it no longer seats.

 

[kphill]

I would take a 3/8 drill bit and with my fingers turn the bit in the valve guide to clean it out and the use scotchbrite on the valve stem and it would last a little while but it would return after a couple months.. Wasn't cured until I replaced the guide and exaust valve. My theory is that because it is a sodium filled exaust valve over time they swell and stick.. Wasn't cured until the exaust valve and seat were replaced..

 

[dschwandt]

Many rebuild kits come w/new valves and for $20 more new guides.
Really a no-brainer when doing a major on a K series.
Just have the shop install them when they lap the new valves in.

FWIW I use MMO in my gas as well 1oz/gal

 

[Greg Riutzel]

1 oz.? That's a bit rich. I do the .4 oz./gal or 2 oz. for the 5 gal. can.. In my VW days the valves were checked every 3K miles at oil changes. There was always at least 2 , usually #3 cylinder for one, that needed a valve lash tweaked. After I started using MMO the adjustments needed dropped off to almost zero, maybe an exhaust valve every other year or so. Now all my air cooled engines get the recommended treatment.

 

[kweimann]

Carbon buildup on guide and valve shaft. Easy enough to clean, just need a head gasket, valve spring compressor, a lapping stick and some compound.

 

[gpapa]

IMHO modern gasoline does not provide cushioning and lubrication for older engines, especially at the valve seat area. MMO in the fuel and ZDDP in the oil seems to have worked for me - time will tell.

 

[RAllison]

ZDDP?

 

[RAllison]

What's that?

 

[danderson]

Zinc dialkyldithiophosphate (Had to look up the spelling)