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HerbP

AC720: If it's not one thing ....

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HerbP
It's a hundred ... I love this tractor, after owning it for about a year but in that year, I've had the engine out 4 times and it seems it's haunted ... Exacerbated is the fact that I only get out there on weekends to use it or try to fix it ... After not-solving but also not finding the mystery starter interlock problem, it just went away so now starts by turning the key, every time, without fail... I don't know what it was so I'm sure it's gone into hiding to strike again at the most inopportune time possible... Now the latest problem... The PO said "change the points/condensor every year, without fail"; so I ordered and kept on hand, a new OEM set of points/condensor... Figured I'd wait for symptoms to start before replacing... Well, last weekend, I thought I had my symptoms ... Previously, the tractor ran great but would sputter under load; like towing a trailer full of yard junk, up a hill, in 3rd gear... I understand, probably excess load on the hydro pump, so back off on the speed and the engine catches up and everything's cool... or switch gears... Well, now the engine is doing the same thing under the slightest provocation... At full throttle, it will run smooth until I start driving and then it will start to sputter/miss... However, it doesn't recover when I push in the clutch to disengage the hydro... There are no attachments on the PTO's either... I can get the engine to recover by backing down on the throttle, waiting for it to smooth out, and then can slowly go back to full throttle (letting the governor spring control the throttle)... So I checked the points, the points gap was fairly small, seemingly due to wear on the resin-fiber arm... I re-set the points gap to .020 per the manual but no improvement. I pulled the points and they were a little carboned up, so I sanded them, reinstalled, re-set to .020, and still sputtering after application of a little load... I broke the seal on the new points and condensor and installed those... Also, no improvement... New symptom after installation of the new points: Now the governor hunts when at idle.. Could be I need to adjust the governor spring? But can this affect high-throttle operation? This is all fairly time consuming because after every test, the exhaust is hot and I don't want to be working near it so I have to let it cool before going back in there. I ran the tractor with the lid off the ignition box and see what looks to be fairly steady spark, in spite of the missing... It really could be fuel delivery. Presumably under load, there would be greater call for fuel than when running at-speed with no load... So maybe my fuel pump is marginal... But then I would expect the engine would catch up when the load was removed.. Which it doesn't. Proceed to checking the fuel. The electric fuel pump is working and seems fine... The air filter was new per the PO and it looks still clean.. It's a Donaldson unit so should be fairly high quality... I assume it must be getting air just fine since it is capable of running at a good throttle level at least part of the time... The PCV breather is clean and not jammed... The choke cable is not interfering on me either... I haven't checked the timing as I don't have a timing light, but the bolts are tight and I can't see as it should suddenly be off... I must say, the idea of a re-power is enticing as I'm getting rather weary of always having a broken tractor... But I feel I haven't reached the end of my rope with the CCKB yet and there isn't anything fundamentally _wrong_ with it... I think it probably just needs a bit of love. So I'm dipping into the well of collective wisdom... Anyone have any ideas that I haven't already thought of?

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HubbardRA
Sounds like your carb is out of adjustment. I don't know much about the CCK engines, or whether they have adjustable or fixed jet carbs. It either needs adjustment, or the fixed jet needs to be cleaned out. That is the first area that I would check.

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CleanBee
These have a history of the points box becoming loose and closing the point gap / making it erratic. Also, if you have a new symptom after messing with something, chances are its related to what you messed with. Dan

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steveo358
I am with hubbard on the carb thing. I have a magnum 18in a 7117 that would never run under half throttle, but smooth as silk at full throttle. I bought a NOS carb for it, the non adjust carb that everyone hates. Once installed, it idles, and does everything perfect. I had rebuilt the other carb,. but obviously something wasnt right inside it. Best 100 I have spent on this tractor.

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midnightpumpkin
Herb, I would be for pulling the carb and taking the fuel bowl off. You cna then flush it with spray carb cleaner and blow it out with air. My 4041 hunted pretty badly until I cleaned the carb up. Problem solved. With a little luck you won't even have to replace the gasket on the carb bowl. Adjusting the carb is another story since the jet is on the bottom and very difficult to reach. I screw the needle in till it seats and then back it off 2 1/2 turns. That's at least a good starting point. Also check that points box to make sure it isn't moving as a previous poster suggested. Hang in there, I wouldn't give up on the Onan. John U

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CleanBee
If my memory is correct, Onan recommends starting both adjustment valves at 1 1/2 turn out. Anything drastically different than this means you have a problem. Dan

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MysTiK
I hear you saying stuff like you are a weekend warrior of sorts, and I love the talk, like this line, "...I feel I haven't reached the end of my rope with the CCKB yet and there isn't anything fundamentally _wrong_ with it... I think it probably just needs a bit of love." I'm thoroughly indifferent to any notions that I might be right off the deep end; and I talk to my tractor, and he talks to me. Sometimes I have to listen to what he says very carefully. Your tractor has you part way there when you say you don't believe there's really anything really wrong. I tend to agree cos you have reported a bunch of stuff about all that. It's a good unit. I think it's fuel problem. Maybe carb clean, maybe settings. But dump the ethanol gas, and never use it again, (no shelf life, separates into water and "goo") maybe try seafoam as a cleanser, and only use PREMIUM GAS. Get a comfy chair, or the tractor seat will do just fine, and a cold one, and go talk this over with your tractor, no stress. It's kinda like that movie the "horse whisperer", only it's "tractor whispering". Listen to it. 8D and feel the LOVE. Yes, I am serious. sm03 A similar approach might work for people too; minor changes in nutrition can make a big diff - it's about those trace elements, and ethanol is not one of them. Better input, better output. Peace.

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JP
Some of the 'common' issues are; loose points box worn plunger/plunger bushing oil in points box from above, they have a seal to help carb/fuel pump/ air filter timing- should be set w/timing light crankcase breather/element Getting these in control should get you where you want to be.

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HerbP
>loose points box I'll check. This must have been an issue in the past because some PO has changed the points box bolts over to a cheese-head allen-key. > worn plunger/plunger bushing > oil in points box from above, they have a seal to help That's interesting. There is definitely oil in the points box and the motor does have a fair amount of blow-by despite the PCV breather being apparently clear, it's clean and the little BB's ... While running, one day, I undid the dipstick/lid and it almost flew out of my hand and sprayed oil all over me... Is the premise that the oil is going to contaminate the points and interfere with ignition? I'll clean the carb and poke around with it this weekend. I've noticed that after I shut the tractor down, the fuel bowl drips slowly from the drain...

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steveo358
I am with hubbard on the carb thing. I have a magnum 18in a 7117 that would never run under half throttle, but smooth as silk at full throttle. I bought a NOS carb for it, the non adjust carb that everyone hates. Once installed, it idles, and does everything perfect. I had rebuilt the other carb,. but obviously something wasnt right inside it. Best 100 I have spent on this tractor.

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dhardin
Your excessive blow-by is causing the oil to accumulate in the pints box. Witch is NOT a good thing. Also I have seen spark plugs that look fine and not to old act this same way. Also a mentioned carb adjustment or bad gas are possibility's. All could be a issue that you may have gotten under control and have fouled those plugs causing it to still act up. This has happened to me before.

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D-17_Dave
All above points are valid and will need attension. You also mensioned only using it on he weekends. How is the tractor stored? If moister can get into the coil it can give the coil all kinds of problems all the way up to just shutting off abruptly once warm. Is this a constant problem, hot and cold? When this starts lightly apply the choke. This will help determine a gas flow problem or an ignition issue. Hope all this helps, looks like you'll have your hands full for an afternoon.

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HerbP
The tractor lives in an unheated garage the entire time... This symptom started only recently, at the end of snow-blowing season... I did have to replace the governor spring with a new replacement, as the old one was stolen during the ring-gear fiasco... However, the tractor ran great after replacing the governor spring for a good number of hours of snow blowing... While recounting history, though, I now remember noticing one other oddity; and that's just before this symptom began, the tractor would backfire on shutdown... Turn off the key, let the engine wind down and then, like a final insult, let out a ginormous cough and then fall silent. My experience with trucks tells me this is timing related which would lend some credence to the notion that the points box could have come loose... I did check with the choke while the engine was sputtering and it made the problem worse by just lightly pulling the choke closed... The problem occurs shortly after startup but not until I assert some load on the tractor (like trying to drive up a gentle slope)... Removing the load (push in the clutch) does not cause the sputtering to go away.. Only reducing throttle until the engine stops sputtering, and then slowly increasing it again to full throttle brings it back to normal, until I apply load again. While sputtering, there is no visible black smoke coming out of the exhaust (as inquired by a PM)... You're right, I have a busy afternoon ahead of me this weekend... Unfortunately, my love for the tractor will have to be doled out in small doses this weekend; as I will have to put on my finish-carpenter cape and attend to other finnicky matters....

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babablacksheep
Hi. Oil should not be in the point box at all, and can cause you to loose fire completely if it builds up enough. You may not see much oil because it drains down after the sit awhile, and then they will start up and run well until it builds up again. While this may be a lot of the problem, it sounds like you need to clean or rebuild that carb.

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Cityboy
My 720 also had some oil in the points box, but cleaning out the crankcase breather ended that. It would also lose the setting on the points because the screw holding the points setting in the back of the box was not able to hold tight.(The tractor would be fine until it got warmed up, then would lose power and even sputter as the points gap closed.) New screws to hold the points ended that problem. Good luck! Dave

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rfsmith1952
I know Autolite plugs that have been gas-fouled a lot simply stop working. Didn't believe it til changing them cured a starting problem on my old L-Head Willys Jeep engine. Now there was a vehicle: 1962 Utility Wagon. It was such a good auto, we called it "Mr. Jeep!" Ahh..digressing again, but I still won't use autolites in anything.

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HerbP
Well, I don't know what to think... I went out this weekend and started the tractor to move some stuff around... Hooked up the little trailer and went up the hill and the tractor performed quite well, actually. All I did was leave it for a week; I didn't do anything to it (though it did have the new points/condensor in it; even though it still sputtered after I installed them last week)... Later in the day, I pulled the spark plugs to have a look and they were black, but not oily.. Just coked up with black soot... So I guess perhaps it's running somewhat rich. I checked the screws on the points box and they were tight and the points box was solidly fixed in place. It was a short weekend for me, just a little over 24 hours so I didn't get a chance to do any serious investigating... I know the problem hasn't gone away, it's just hiding in wait for when I hook up the tiller.

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HerbP
4 day weekend out here... I thought I'd drive it around with the hood open and see if I could cause the problem to happen again and see if I could see something... She who must be obeyed wanted the garden tilled so Superintendent Chalmers was going to have to put out.. It didn't take long antagonizing it by putting it in high gear and driving around before it happened again... Just as it happened, I saw the choke flap push back against the cable. So I pushed the choke back down with my thumb and lo-behold, the engine recovered... I managed to get the whole garden tilled occasionally having to reset the choke. What appears to be happening is the choke cable is loose enough that the engine can, under heavy vacuum, suck the choke closed enough to push the lever up... A simple problem that I'm going to have to work through... Just after tilling the garden, I used the tractor to go out and install a sign at the road... After returning from that chore, the CCKB threw a spark plug from the left side.. The hole was completely stripped. I did notice that the threads weren't looking so hot when I pulled the plugs last weekend but it went in relatively tight... Turns out one of the previous owners had put the plug in with some kind of thread locker hoping for the best... I'm going to have to heli-coil it or see if I can find an insert... Which means pulling the head, presumably... Are the head gaskets on these things reusable copper or one-time-use? Anyone have experience heli-coiling these things or should I source another head?

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MysTiK
some type of thread locker? like high temp LocTite? You would need some trace of thread for that. If it's really "completely stripped" that probably won't work. If there's some thread, maybe.? Undoing a loctite bolt always sound like -bang- you broke the bolt in half, as it lets go. Man, that just sucks; I thought you had it fixed w that choke thing. That was interesting; and a carb adjust problem that seldom gets mentioned. Tricky lil item. At least you have an advantage now; your tractor has told you about 2 problems - one minor, one for the long haul. I think the tractor has had enough too - spitting plugs, that's a definite statement. By the sounds of it, the PO was the real problem. Don't quit now.

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HerbP
maybe thread locker or maybe JB-Weld or something. Hard to tell. Regardless, certainly not anything useful.. But you're right, the tractor definitely did make its case known... It's very unhappy about something. It looks like 14mm x 7/16" helicoils are fairly common off the shelf items. Now I just need to decide whether to do it in-situ or pull the head.

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HubbardRA
I know that I am different, but I would just install the heli-coil with the head on the tractor. Put the plug back in and put it to work. After you get it running again, it sounds like you really do need to lean out that carb some. From my experience, carb adjustment is usually the first thing needed, but the last thing anyone gets around to.

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rfsmith1952
I would put the helicoil in with the head on. Get the piston pretty high. Be as careful as you can about dropping metal parts, or dirt down the hole. If you have a magnet on a stick for fetching screws from tight places, run that around inside before you button up. If the piston is up high enough, you may be able to vacuum any particles or dirt out. I've put helicoils in VW engines without taking the head off, twice. Both times were successful, and lasted longer than I owned the car. While it pays to be thorough and do things right, there comes a time when commonsense, time and money prevail. It's not the Space Shuttle. ;)

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HerbP
heh. I think the magnet would be a good idea, if the head were not made of aluminum. :-) I think I'll do that though. Push the piston up to TDC, put some grease on the tap, and then blow some air down the hole in hopes that any other shavings come up...

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