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656 Gas Engine Issues


1206man
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I picked up a 1966 gas 656 late summer and ran into an engine issue that is starting to baffle me.  The tractor has more than 6,000 hours on it and I don't believe the engine has ever been rebuilt.  I do believe that the engine has had some work done to it but without tearing it down I cant be certain.

When the engine is cold it works with a 7' rototiller great (at maximum 8" depth - tiller company indicates 60 HP required - my 504 can handle it but it is maxed out at 4" depth).  Once the engine is under a hard pull it heats up quick nearly to the point of overheating then sputters a few times and quits.  If I am not quick on the clutch it will totally stall out.  I can't raise the hitch fast enough nor can the draft control react quick enough.  

I see some blow by smoke, but it doesn't burn more than a quart of oil running all day disking.  My gut is telling me I am missing something obvious.  If I can't figure it out soon, I will probably have to get it hauled in 50 miles to the Case IH dealership and dyno test it to have them help me figure it out.

I am retired from farming but still put out about 10 acres of pumpkins, squash and ornamentals to sell so the tractor doesn't get a lot of long hours.

Any ideas will be appreciated.

Thanks

1206man

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A lot of people put hot plugs in an old engine like this because they foul plugs in light work. When put to work like your doing. It will act just as you describe. If thats not it. There is a whole list of possibles but that is my first check.

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soon as it stops feel the coil, if its hot you have found your problem, bad coil and that is what it will do. spark plugs do not make an engine just stop. 

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656 isn't big enough for a 7' tiller I don't think.  I've ran a 10' tiller at 8" and it worked a 1066 absolutely to the max.

Sounds like a hot ignition system to me as well, coil or plug's or both.  But sounds like you are working it way too hard with that tiller. 

I guarantee a 6000 hour gas 656 has been overhauled at least once.  Those old gasers didn't run those kind of hours without getting rebuilt.  4k I can see, but 6 is a real stretch.  If it hasn't been, it's certainly due. 

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Thanks everyone for the input so far.....

I had a 560 gas on the tiller running it with no problem so the 656 should handle it too.  I sold the 560 to buy a loader tractor a few years ago.  I also used my U504 on the same tiller for a whole year before I got the 656.  Granted I couldn't get it as deep, but it did the job for the duration.

I can kick myself for not thinking about the coil issue that it could be.  I had a coil go bad on the 504 years ago and I had a real struggle finding that issue.  It acted the same way. 

What I found on that one was that when it would heat up a tiny hairline crack would open up (expand) on the top of the coil and arc / short out causing the shut down.  I never would have found it if I wasn't playing around one night plowing after dark and turned the headlights off (I always liked to see the flame coming off the stack - LOL).  I noticed the arcing of the coil in the dark.  

Side humor:  My brother and I used to play chicken with each other on our 3/4 mile long rounds at dark plowing in the moonlight with the lights off of our 706 and 806.  Crazy but it is fun listening for the other tractor (you notice the slight rpm differences first) then notice the stack with a flame about a foot off the muffler coming back in the opposite direction.  Being that I am the younger brother, I was always stuck with the 706 (gas) and he had the 806 (diesel).  It did turn at slightly higher rpm's so I had fun lapping him after quite a few rounds.  I would always wait until I was practically climbing on the tail wheel of his plow before I would switch the lights back on and scare him....  Younger brothers revenge!!!  You wouldn't dare do something like that today!  Surprised we are both still alive....

Anyway, I replaced the coil on the 504 and have never had an issue with it since.

I will switch out the coil and see if it helps.  If it doesn't I will replace the plugs with the proper plugs per spec if they are hot ones.

Thanks again everyone,

 

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