Case 446 Tractor Onan Twin Engine??


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Old 02-17-21, 09:24 AM
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Case 446 Tractor Onan Twin Engine??

I have an old case tractor with a twin cylinder Onan engine. It was always a hard starter. I rebuilt the carb and adjusted the valves to specks as it was off a bit. Put everything back together and did get it started. and ran good, just needed to adj carb but -24 outside, so I have been waiting for it to warm up. Went today to try it and it would not turn over. Battery did not seem to hold charge, so changed with another battery. Now it turns over soo slow it will not fire. Like there is too much compression. Pulled the plugs and it turns over fine. Anyone have any ideas? Maybe its a bad battery? It is in a heated shop so its not the cold.
 
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Old 02-17-21, 11:07 AM
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could be many things would check battery voltage while cranking maybe check voltage drops on cables while cranking if the battery voltage is staying up at 9.6 or more would look at your cables and starter connections.
 
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Old 02-17-21, 11:33 AM
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-24 f or c is very cold for a battery and the oil is like putty. It's no wonder it doesn't want to start. If you have to start it I would bring it inside and warm it, otherwise I'd try to at least warm the battery and it would be better if you could also warm the engine and it's oil.

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I once had an engine that could not be started below 32f (0C). The tolerances in the engine were such that below a certain temp it was metal on metal and very bad to even attempt a start. I had a kerosene fired heater cart and would have to warm the engine until the oil and cylinder head temps were above freezing before hitting the starter.
 
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Old 02-17-21, 01:35 PM
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Will check the voltage, cables are good, clean connections. Will also look at the starter. As I said it is in a heated shop its not cold. Goofy thing is when I first started it after I rebuilt the carb it turned over great and started. Couple days later would barley turn over??
 
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Old 02-17-21, 01:49 PM
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Sure sounds like a weak battery. The only way to tell is to test it under load.
 
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Old 02-20-21, 01:37 PM
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Boy this was a learning experience. bought a new battery and it did the same thing??? So I took the leads off starter solenoid cleaned them up and it turned over and started right up. I know you said to check connections. Now my question is, I shut it off and it would not turn over, it just clicked. ?? I turned on key and took screwdriver and shorted across solenoid and it turned over and started right up. So my guess is its bad. Now I have attached pictures of new one, it is different, and the old one. Does it make a difference which is positive and negative? Also there is a black on top and yellow lead on bottom with push on clips do they make a difference?

New One

Old one installed
 
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Old 02-20-21, 03:33 PM
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any markings on the smaller side terminals like an s or i, if not would assume they are the same other than appearance , on the larger terminals really does not matter as long as you keep the red and blue together on 1 of the terminals and the black on the other.
 
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Old 02-20-21, 05:47 PM
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I looked really careful on the new one and no markings at all. Will give it a try tomorrow?
 
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Old 02-23-21, 01:17 PM
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I am at a loss?? I replaced starter solenoid, did the same thing. Nothing. Shorted across the two terminals on solenoid and turned right over. Do not think the other one was bad?? Any ideas what to check next. It worked when I got all the terminals cleaned, and started engine, adjusted carb and shut off and then did nothing? Thanks for your help
 
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Old 02-23-21, 05:54 PM
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Check the small wire going to the spade terminal for 12 volts when the key is turned and make sure the solenoid metal mount is grounded. Sounds like a small problem - should work.
 
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Old 02-23-21, 10:38 PM
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looks like its an isolated solenoid to me, and may not need to be grounded to the frame, at the spade terminals you should have power on one wire while the key is in the crank position, the other wire appears to provide ground and goes through a neutral safety switch and then to ground.
found one operator manual online but it may not apply to your model as they made this tractor for looks like 16 years not sure how many wiring diagram changes there may of been through the years, page 40 below.
Case 446 Operator's Manual No. 9-6422.pdf (casecoltingersoll.com)
learn how to do voltage drop testing, and it can be used to test wiring, switches, connections and probably might save you some time. figuring out the issue couple of videos below may help.
How to (voltage drop) test a starter motor circuit - YouTube
Voltage Drop Test - Made Easy - YouTube


 
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Old 02-24-21, 06:41 AM
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Wow, great info, Will check it out and see if there is power to the spade terminals, something must be loose or? Will let you know Thanks Soo Much!
 
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Old 02-24-21, 06:53 AM
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You can use a test light to check it. It sounds like you have either a bad switch or a break in the wiring. Probably the switch.
 
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Old 02-24-21, 09:55 AM
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I think I narrowed it down to the key switch. I checked all the connections, voltage to the switch, turn key on no voltage. In messing around with the wires the electric fuel pump would not even go. Played with the switch a bit and it finally came on. Will find a new switch hopefully. Will let you know Thanks Again
 
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Old 03-04-21, 07:38 AM
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Back to the drawing board. It's not the switch. It has to be a connection from the two wires that plug into the solenoid not the main wire?
I have new starter solenoid, Removed and cleaned all contacts to the battery, solenoid, starter, ground. The wiring in this tractor is a mess. Wil have to try and trace them down and find out what the problem is.
 
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Old 03-04-21, 09:04 AM
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If you jump from the battery cable at the solenoid directly to the spade on the solenoid will the solenoid energize and spin the starter?

If so ...just run a wire directly from the start terminal on the switch to the spade on the solenoid. Check for voltage before you hook it up With that working you can work out the wiring harness as you see fit.

The other things that need power, though is the electric fuel pump you mentioned and if outfitted with one, a solenoid on the carburetor bowl. Also the kill wire terminal on the switch would have to access ground.
 
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Old 03-04-21, 02:09 PM
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I am at a loss. I tried what you said, and I appreciate the reply and nothing seemed to happen. As I have said with key on, I take a screwdriver across the two connections on the solenoid it turns over and fires right up. I have attached a photo of the solenoid. Nothing happens when I try to spade terminals.?? This is the new solenoid. I have 12 volts across the two main terminals. There are 4 wires on the switch, light, fuel pump, one is hot power I get 12 volts when I connect to wire and ground it, and one other not sure where it goes yet. Solenoid top wire is from the battery and the bottom wire goes to starter
 

Last edited by dreamen; 03-04-21 at 02:26 PM.
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Old 03-04-21, 04:02 PM
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Disconnect the two spade terminal wires from the solenoid and use a test light to check each for current when you turn the key to start.

While you have both wires off the spades take a short jumper wire and jump 12 volts from the red battery cable at the solenoid to each of the spades. One should trigger the solenoid.

Does your engine have an external ignition coil with points and condenser?
 

Last edited by marbobj; 03-04-21 at 05:12 PM.
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Old 03-04-21, 11:17 PM
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are you not able to do a voltage drop test even after watching videos?
really need to narrow down the problem, either going to be the power side witch would be the spade terminal that goes to the ignition switch probably yellow but the wiring diagram does not show wiring colors probably same color at ignition switch though.
or the problem is on the ground side probably black or the spade terminal that goes to the neutral switch.
your missing one of those and suppose you could just use jumper wires and figure out witch side has the problem.




 
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Old 03-05-21, 01:34 PM
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I am almost embarrassed to post an update. I got the tractor running, Checked all the contacts, grounding of the solenoid, did a voltage drop test, and started one wire at a time and traced them. Took the access panel off and I found a cut off switch that was connected to the lever on the side of the tractor to engage the blade. I must of bumped it, as soon as I pulled it back about 1/2" it fired right up? I hope someone else learns from this. One lot of time, and changing switch, solenoid, etc. Good thing is runs great, with carb rebuild. Get the mower deck on now and ready to work as soon as all this snow melts. Thanks for all the help with this, really appreciate it. I know I learned something. Have a Wonderful Weekend!!
 
 

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