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leeave96

Onan & Simplicity Question

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leeave96
Did Simplicity ever use the Onan P220 engine in any of their tractors? Reason I ask is that I've got another color tractor that is powered by this engine. I am having some trouble with the engine and am looking for some experienced users of the P220 to whom I can inquire as to what's going on with my engine. I know that several makes of garden tractors used the Onan Performer series engines, but can't recall if Simplicity used them and if not, why. Thanks! Bill

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D-17_Dave
No, Simplicity never used this engine. However, there are a tremendous amount of people on here with experiance on those engines that should be able to help out with your problem. With the exception of a few personality differances between engines, an engine is an engine so the same diagnostics and problem solveing technics apply. The exception would be Tech. engines. Nothing works for very long and you can't fix em'. They came broke from the factory.

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BenB
Dave "The exception would be Tech. engines. Nothing works for very long and you can't fix em'. They came broke from the factory." I have never heard about tech engines, would you please explain what they are/were? Thanks, Ben

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D-17_Dave
I was refering to Techumse emgines. I've never seen a "good" one. I've seen how different manufacturers make a lot of stuff over the years. Tractors, trucks, engines, hydraulics, I've just seen a lot of stuff. I enjoy working on most things just to tear into it and find out how they made it. Most are made with a certain frame of mind set and a certain level of metal abiliaty cetered around the era they were made. Nothing on a tech. engine works or makes sence. It looks like they went out of their way to build a product that had built it failers so they could sell parts or replacement engines. I know a lot of manufacturers do this now and it gripps me to see it. What really bugs me is seeing them in such simple applications. Briggs and Kohler made tremendous business's and reputations off of building respectable, dependable, and easy to repair in the field by most laymen, products. Yet Tech. built something to sell. Even Murry's used Briggs for the most part. I ohnestly think that if Sears hadn't used Tech. engines they would have been gone a long time ago. This has got me to venting some and I'm certainly not directing any at you or anyone else who reads this. This is just how I feel.

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lboy1971
I've had decent luck with Tecumseh engines in my Sears and Bolens tractors. Better luck in fact than the ROD blowing Kohlers. I still prefer cast iron Briggs. In fact, Kohlers are the only engines I've had blow RODS.

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leeave96
Firstly, much thanks for your interest in my Onan! Here's what I've got going on: The engine is a 20hp Onan, model P220. It has an aluminum block. The symptoms are that the cylinder near the steering wheel is misfiring. It will misfire until the cylinder goes dead over, a few minutes - after a new plug is installed. For a time, when I got the tractor, it smoked like a freight train, but that has stopped as what ever oil was in the cylinder/muffler has burned out. I set the offending piston such that the intake and exhaust valves were closed, removed the spark plug and applied air to the cylinder. Nothing leaked out the carb, exhaust or the dip stick - Good news! Then, I did a compression check (cold engine) and got 110 psi. The manual calls for 75 - 115 psi. Soooo, I think I"m good on the compression. Would a warm engine change this value very much? From the above, can I rule out bad rings, broken valve springs or loose valve seats? I guess I"m back to having a look-see at electrical. Question is - what should I check next? I"m getting spark at all times. Is it possible that I have a weak spark and if so, how does one check that? Any ideas, tips or advice would be much appreciated. Scratching his head, Bill

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D-17_Dave
first off, change both plugs. With this engine haveing electrinic ign. and it's track record I dought that there is much of any problem w/ the ign. other than plugs or wires. Next, to answer your ? about compresion after it's warmed up, it would increase after it was warmed up while the oil is all the way around the rings. ie, fluid helps seal up any space allowing leakage of compresion. Therefor it will go up while warm. It will also increase when the engine is running due to the speed of the piston doesn't allow time for as much leakage before it fires. Next thing after replaceing the plugs would be to check the valve/tappet clearance. These blocks being aluminium tend to flex more. With the block heating up and the vavle stem heating up the different alloys exspand at diff rates and this could cause a seating valve while cold to begine leaking compresion when warm. Since the engine cranks and runs fine till it heats up look for things that change when hot. Also I've seen this before on these style onan's. Hope this helps,Dave.

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UCD
Run the engine and get it hot then do your compression and leak down tests. You could also have a bad head gasket leaking after it gets hot. Also bad intake gasket on that cylinder. Crack in intake runner on that cylinder that opens up after getting hot. With engine running spray carb cleaner or a water mist from a spray bottle around the base of the carb and intake runners and base gaskets. If engine smooths out you have an air leak to that cylinder caused by bad gaskets or cracked runners.

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leeave96
Well, I spent some time over the Christmas & New Year's holidays with my mis-firing Onan. Here is where I was at with it. I found the compression OK and started thinking electrical again. Here's what I covered and where I am at: I checked the ignition module, condenser, plug wires and all check out OK. Next, I checked the tightness of the intake manifold with the thought that if there was a leak between the carb and engine intake, then this could cause the mis-firing. I found one bolt slightly loose on the side engine that is NOT mis-firing. Tightened it up and no change. At this point, I decided it's time to dismantle the engine. But first, I wanted to remove the intake and exhaust valve covers and see if I have a broken valve spring. All is OK there. In removing the covers, I had to remove the intake manifold and muffler assembly. This is where it get's interesting. ALL of the valve seats are visible from these ports and have NO evidence of moving, even when I turn the engine. However, the intake valve on the cylinder that IS firing, has some residue of burnt oil around the head of it to some extent and on the portion of the valve stem that does not slide thought the valve guides. The intake valve stem and port of the mis-firing cylinder is very clean. So where does this leave me? Not sure. I'm thinking about putting the intake and exhaust manifolds back in place with new gaskets and start replacing some electrical components starting with the condenser and then the ignition module. Before I do this, any suggestions would be appreciated. Scratching his head...... Bill

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leeave96
The Onan is running again!!!!!!!! Firstly, much thanks for everyone’s suggestions as to how to fix this engine. Let me back-up a bit and review what the symptoms were. At first the engine smoked like a freight train and missed on one cylinder. The plugs were fouled and after a new set, the engine ran intermittently on both cylinders and then one, but in running it for a few minutes, the smoke cleared and never returned. I checked the ignition module, plug wires and condenser – all were OK. At this point, I start looking for a loose valve seat, broken valve spring or valves out of adjustment. I pulled the intake and exhaust manifolds only to find that – that stuff is OK. I also did a compression check and it was to spec. What to do now? Carb looked clean and OK with air passing through it – no blockage. After some tinkering, here’s what was wrong. The high speed jet had backed out of it’s seat to the extent that a washer that sits in front of it had fell into the carb body – causing this fixed jet to be out of adjustment because it was not seated. For whatever reason, all of the gas was going to one cylinder and the other cylinder was getting almost nothing – not enough to fire. Sooooo the misfiring cylinder’s spark plug looked very dry while the firing cylinder’s plug was black from to much gas and after a while, it fouled out. Clean everything up and it would run a bit on 2 cylinders, then 1 and quit. Reassembled the high-speed jet as it should be in the carb and BAM the engine runs like a new one!!!!!!!!!! This one about drove me crazy! BTW, this Onan is on a Wheelhorse 520H with 40 original hours. Thanks again for all of you help! Bill

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Floydster
The Onan P220G engines are notorious for having loose valve seats. If the engine fins are not kept clean and the engine over heats, it is for sure a valve seat will become loose. I have two in my shop now with that problem. Both came out of JD 420's. Floydster

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