2166 engine acting up

[gsmyth]

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Cub Cadet 2166 (MTD), sounds rough

Starts relatively easily, idles fine, runs forward and reverse, no sputtering or hesitation when switching direction, no oil loss, no transmission fluid loss, no teltale fluid inside engine or transmission housing. air fins clear, new air filter, new fuel filter. Belts are good and run well. New gas. Carburator seems to be doing its job, but its adjustment I know nothing about. Speed limiter plate is at the max limit when throttle is full - not loose, no play. W/O air cleaner and ether in carb still loses power. Runs sideways (across hills) well enough but when going up hill loses power to about 1/2 normal speed. I no longer hear the hum of the engine, but to my ear a minor miss or clacking. Exhaust is hot and steady but I probably don't know what to look for. I don't know where to look. I run full throttle when it warms. Power loss started during cut last week about 2 hours into a 3 hour cut. Just slowed down when I turned up a hill that it pulled easily moments before. Without some method of engine analysis my list of possibilities to look for are exhausted. I'm at thinking some sort of leak. Where do I search next? Is there a standard idle speed and full throttle RPM? Am I at the point of tearing into the engine? Valve? gasket? If so I'm game, but never done it on this machine. If it has to go back to the sales company guesstimate a number of hours for repair? Oh, can it be run this way without damage (or further damage)?

 

[kmcconaughey]

Gary, hang in there, hopefully Jim D. or someone that knows about the 2166 will find your post and offer some suggestions.

 

[jdiederichs]

Gary,

That is the B/S twin cylinder 16Hp Overhead valve engine in yours, correct?
One problem that they faced was the "sticking valves when hot" syndrome, due to the ethanol content of the gasoline. It doesn't matter which food source the ethanol was derived from (corn, sugar beets etc)all of the foodstuffs have one common ingredient, sucrose derivatives! You know how sticky cotton candy is right? Well, this is similar in fuel form, it leaves a very sticky substance on the valve stems and when heated up it actually causes valve sticking issues on these engines.

How to defeat this? Heavy doses of Sea Foam in gasoline will help, although it may take some time. Changing your gasoline source is a good start also, try one that is ethanol-free even though it costs more it will speed up the valve cleaning along with Sea Foam. In my area Kwik-Trip sells premium w/o ethanol, as an example.

Having one cylinder 'drop out' on a 90* v-twin is often hard to notice while mowing, except for the sudden loss of power it still sounds nearly the same. Not to say you don't have an ignition module going bad (it happens too)but in your description I am betting on a sticky valve. Those engines were especially prone to that problem.

As an alternate plan, you could remove the valve covers and rotate the engine by hand, carefully watching as each valve opens and closes. You may see the offender, a sticky intake in most instances. Spray the valve stems with PB Blaster and spin the engine over with plugs removed, watching the valves. Once they are free reassemble and follow gas instructions above.

 

[kmcconaughey]

Jim, I knew you'd come through with a suggestion for Gary!

 

[gsmyth]

Thank you Jim. The valve is a leading contender. Last week it was 95 degrees and humid as can be. With the weather and engine working hard on hills I'm leaning strong to your response. I asked the dealer if there was a service bulletin but he didn't say anything. Later, one of the service guys asked if I had valve problems but caught himself and didn't say anything after that. I'll take your suggestion and work it for a while. I'm betting that it works. Damn, if they know that this engine does this why didn't he just tell me? Thanks again for the reply.