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jverhaag

4041 won't start. Bad valve???

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jverhaag

I need the collective wisdom of the group.

Yesterday the tractor started running rough while mucking stalls. She acted like she had fouled a plug. She eats spark plugs so I wasn't surprised or concerned. I limped her to the shop. She would barely pull herself along without pausing to let the engine catch up which is unusual. Parked her in the shop to cool down to change the plugs.

I tried to restart her this morning. No go. She will catch but won't run.

Changed the plugs, checked the gap, new plug wires, and checked and clean the points. Pulled the air filter and cleaned. While filter was out I tried to restart her. Still no luck.

Although she will catch and try to start then back fires through the air box.

Pulled the left plug, facing forward when I noticed the exhaust pipe on that side was cold and checked for spark. Good spark. Checked spark on opposite side, good spark. What I don't understand is why would the exhaust pipe on one side heat up and the other not if there is spark and fuel? Oh the plug was wet as well.

So I have spark, I have fuel, I have air, timing is good, she is trying to start but the left cylinder appears as if it isn't firing and the right cylinder can't run while dragging the left cylinder.

I'm wondering about a stuck valve or worse, a hole in the piston. But don't know enough about these engines ( or any engine for that mattersm01) to say for sure. Thoughts?

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midnightpumpkin

John

I had one with similar symptoms. It turned out to be a gross air leak in the intake manifold joint on the side that wouldn't fire.

Try spraying carb cleaner around the intake manifold joints while you crank it, see if it will fire that way.

Good luck,

John U

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720nut

Good point John but sounds like he needs to pull heads and check things out new gaskets wouldn't hurt a thing. My starting issue have almost all been points related. Just my $.02

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wwbragg

If there is spark on both sides, it's probably not the coil. But since the plug is wet and that side of the manifold is cold, it sounds to me like a compression issue. Check the compression (both sides). If the difference is noticeable, could be a head gasket, a cracked head, a cracked valve or even a broken ring.

Wendell

Beat to fit and paint to match.

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steve-wis

Maybe a piece of carbon came loose from the head or piston and is stuck in the intake valve? If it is firing back thru the air cleaner it should be the intake valve, if one is open.

Steve

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jverhaag

Okay. Started at the top and went down the list. (Skipped pulling the head for now)

Tried spraying around the cylinder head, above and below, everywhere I could get,

no go.

Tried switching plug wires, no go

Tried switching plugs, no go

Cleaned and adjusted points, no go. I'll order a new set just to be sure.

Pulled the valve cover, cranked engine, both valves moved. Still no go.

I have not checked compression yet. Couldn't find the compression tester after an hour of "cleaning" the shop. Guess I'll go buy another one. And the mrs. Wonders why I have three of everything. sm01

I suspect the compression test will show a dead cylinder tomorrow evening!

If I have to tear it down as suggested (sounds like the next step now that I retread this) can the head gaskets and rings be found?

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720nut

yes gaskets are available and rings found off a guy in Ohio, bought complete gasket set and rings and rod bearings about $250. Main bearings for some reason are unavailable. but do some checking people seem to find the unavailable somewhere. Just my $.02

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isetta

Lacking a proper compression tester you might try a quick finger test to see if you can tell if one side is way more, or less than the other.

If you are certain that the ignition and fuel systems are good, no manifold leaks as John described then pulling the head would let you see the condition of the valves and seats. If you find there is a piece of carbon between valve and seats as Wis suggests, then clear it and re-assemble with the old head gasket, see if that corrects the problem. You can then order up new gaskets as needed.

Also interested in why it eats spark plugs? Does it burn oil? General overall mechanical condition good?

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jverhaag

Compression test completed. 60 psi on each side. Technically 59 on one side 60 on the other. I checked both tractors, (I only have two) both engine tested at 60 to 61.

Sooooooo, what does that mean. Good, bad, weak, etc. thoughts.

Do I need to buy a leak down tester or does this tell me what I need to know.

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jverhaag

Isetta, I'm not sure why she eats plugs. I know she is running rich. I need to replace the carb. It runs rich or not at all. John gave me numbers of new carbs that will work. I just have'nt had the money for that. So I change the plugs, often. She starts running really rough and I know it is time. I change the plugs and she runs like a champ for about fifteen hours then it's time for new plugs.

I think I will take yours and wis advice, take the head off and see what is going on in that cylinder this weekend when I have a couple of hours to tinker.

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wwbragg

I agree with Isetta; 60 psi is simply too low. Time for a rebuild. Parts for the Onan CCKB will be hard to come by and expensive. I suggest a repower kit from Small Engine Warehouse of get a Harbor Freight 22 HP twin. They are on special right now for $699 but you will have to fabricate the flywheel/driveshaft adaptor. Someone covered this in a previous thread.

P.S. I just looked on SME and they have a used CCKB for $700. Ckeck it out.

Wendell

Given a foolproof system, nature will provide a dumber fool.

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dhoadley
quote:Originally posted by jverhaag

What is SME?


id="quote">
id="quote">I think he meant SEW. Here's the link.http://www.smallenginewarehouse.com/Used-CCKB-2733-3.html?sc=17&category=1709445

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Brettw

I would look closely at your compression tester. 2 engines, 4 cylinders, all of which should be at about 100-120, yet all 4 read about the same @ 60 PSI. That sounds a bit suspect. 3 of the 4 cylinders run? But one won't fire, yet they all have "bad" compression according to your tester.

Just seems suspect to me. I would want to verify the compression before tearing apart and rebuilding / repowering. If you had one @ 60 and the others were at different levels maybe it would be more believable, but it almost sounds like the tester stops out or quits at about 60 PSI.

It could be they are all at 60, but I wouldn't bet on it without a second opinion (read, tester).

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phillobbezoo

I know on the 3 that I have they range from 105 to 120, I don't think they would run on 60 psi, and no there isn't a compression release. It does sound suspect that both motors have 60 psi and one runs and one doesn't

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jverhaag

Compression tester is a 30 dollar unit from harbor freight. Brand new. I retested both engines, throttles opened, throttle closed, standing on one foot, etc. still come in at 60 to 65.

One engine runs like a champ. Dozer blade mucking stalls, runs great. But it still tested at 60. Is there a way to check calibration?

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isetta

Does your compression checker have about the same amount of threads on it as the spark plugs in the Onan? One opinion is that low compression readings result from a compression checker with less plug depth resulting in a larger combustion area. Not sure I have experienced that but interesting to consider.

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720nut

I agree with Phil can't see an engine being able to run at 60 lbs. Need to get good gauge and recheck. Rick can't see where little bit of threads would make that much difference. Only way I know would be to have a gauge you know is accurate and check it against it, Tell Harbor Freight that you think it is wrong and they will give you another to try. I still say pull heads and look. Just my $.02

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