K321 Laboring hard after warming up

[vthomley]

One of our 149s has an issue, my dad and I have 4 or 5 of these awesome 149s. One has a loader wrapped around it, one is sorta the Tiller 149, one has a 12hp motor, and I think 2 more

The 14hp K321 in one has an issue. After warming up for few minutes it starts labor really bad at higher speeds. We have changed most everything - cleaned carb, adjusted carb, different carb, different coil, different condenser(its on the correct terminal on the coil), adjusted the valves, check the breather, new head gasket, ground the head to be flat, no balance gears in this. please advise. Govenor gear worn out? this 14hp has overhauled 5-0 years ago, it ran aweomes until we install the snow plow on it last fall, of course we never plowed any snow this winter, this spring we have attempted the things above.

I know we need to get a pic of all these 149s together

Thanks,

 

[kmcconaughey]

Vince, perhaps there's a fuel flow issue, have you replaced the fuel lines or fuel filter?

 

[vthomley]

Kraig, fuel is fine I do believe. I'd like to think its something simple but I've never heard and engine do this, neither has my dad.

 

[jbaker]

Probably already checked might not matter but how are the points and timing and no mouse nest in that cover there to prevent air flow and make it overheat

 

[Kittermankadets85]

Check butterfly shaft in your carb. I had a 10hp do same thing years ago and turned out the carb was worn pretty bad around the butterfly shaft and it was sucking air I assume new carb fixed the problem. Also might double check points gap and cleanliness . Good luck with it

 

[vthomley]

Thanks for the replies, keep them coming please.

Jeff, we checked and reset the points and timing, checked it again using Matt Gonitzke's method.

Kitterman, we have had 3 different carbs on this motor.

 

[Kittermankadets85]

Is the cylinder worn or the rings? Sounds like it’s loosing power when it gets hot could be bypassing compression idk just thinking out loud now

 

[mgonitzke]

I had an 86 that did something like that. I did all sorts of stuff, and nothing fixed it until I removed the valves and happened to notice they were so worn that the edges were basically a knife edge, and you'd lap them and then they would warp the next time you ran the engine and the problem would return. Two new valves solved it.

 

[gchunnett]

start by disconnecting the fuel line from the carb and blow back into the tank (with cap loosened), reconnect line to carb and see if problem persists, the fine mesh in tank may be restricting flow, then check the cap is breathing and not restricting flow after a while, i.e run it hard with cap loose (or off). These quick checks can possibly save you a strip down.

 

[bfleisch]

Is the governor responding when you idle up?

 

[asmith]

Did you check for the mouse nest in the flywheel cover as suggested? It happens.

 

[vthomley]

Alex - no mouse nest
Bill - Governor seems to be responding when we idle up.
Gordon - will be rechecking this fuel flow
Matt - Valves were new when motor was rebuilt, governor was also new at the time. Valves were rechecked recently

My dad exchanged a motor from another 149 to this one to get his garden tilled. He says it's easier to change the engine versus changing the rototiller. After the garden gets tilled and planted we will be back to diagnosing this K321 14hp issue.

Thanks everyone.

 

[jbaker]

Hes right on the easier part

 

[vthomley]

Ok got some news. The head had 2 or 3 loose bolts previously. They are now loose again. These were tightened to 30 ft lbs but after running the engine for a short time they are loose again. Why does this happen? Does the head bolts need to be replaced or is it the threads on the block the issue?

This motor got taken out, swapped with another K321 and the garden got rototilled. This motor issue will be put aside for a bit for my dad has other things to attend to such as the garden, being retired, golfing, relaxing, watching the birds, etc. Oh yea and maybe looking at the new to us 123 lol

 

[mfrade]

It could be either the bolts or the block threads. Typically the heads & head gaskets settle so it is common to check / re-check the torque. But it shouldn't continue to change after a time or two imho.

But do not exceed the number of ft. pounds! More won't be better.

 

[mgonitzke]

The iron block and aluminum heads expand at different rates when heated, so this is perpetually cycling the head bolts. They have to be retorqued after some run time on initial installation, and lately I'm of the opinion they should be checked periodically even after that.

Are all of the head bolts OEM/grade 8? Are they in good condition?

 

[Beltrack]

Based on some experience with other air cooled aluminum heads, at this point I’d remove the head a check to see if combustion gasses have channeled a grove or if the head is warped. If all is good, replace with a new gasket and, depending on what others here say, I think I’d use new head bolts.

Ok got some news. The head had 2 or 3 loose bolts previously. They are now loose again. These were tightened to 30 ft lbs but after running the engine for a short time they are loose again. Why does this happen? Does the head bolts need to be replaced or is it the threads on the block the issue?

This motor got taken out, swapped with another K321 and the garden got rototilled. This motor issue will be put aside for a bit for my dad has other things to attend to such as the garden, being retired, golfing, relaxing, watching the birds, etc. Oh yea and maybe looking at the new to us 123 lol

 

[vthomley]

Well heres pics of the head. Last time it acted up my dad left it run for a bit and it just quit. This had been tightened to 30 ft lbs then tested by rototilling the garden for only a few minutes

Another head has been resurfaced to less than 2 thousands and will be installed with new grade 8 bolts and nuts

 

[dschwandt]

Looks like it was run waaay too lean.
How did you resurface the replacement head?

 

[kkuhlman]

I put a new head on my k321 and blew a hole through the same spot about ten yeas ago, the parts dealer said defective head. Replaced with a new one and has been running fine since!