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Discussion Starter · #1 ·
Greetings, last fall I purchased a 1977 446 (with rotary mower). The tractor was stored in my garage all winter. Last month (April) I changed the fluids, installed the mower and cut 2 acres. No problems. Today I had plans to cut 5 acres and the engine would not start. Battery holds a charge, but no action or sound when I turn the key. I believe that I have traced down the issue to the PTO safety switch ... but I am not 100% sure. The reason I suspect the PTO connection is involved is because I was able to get a few seconds of engine cranking when I re-positioned the PTO engaging lever a couple of times. But all later attempts of finding that 'sweet spot' with the PTO lever have not made any connection.

I have downloaded the proper parts manual for my serial number and studied the wiring diagram and the PTO clutch linkage assembly but I do not understand how the PTO linkage 'communicates' to the safety switch.

If anyone could assist with this trouble-shooting it would be appreciated greatly.
 

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The PTO safety switch is wired in series with the neutral safety switch that is under the dash and is effected by the position of the travel control lever. Have you attempted to wiggle the travel control lever in or around the neutral position? Try holding the PTO lever back while turning the key. One of my 448's has a touch PTO safety switch and I have to pull back on the PTO lever while turning the key to keep the circuit closed.
 

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This is a shot in the dark, but when I had a similar problem recently, it turned out to be a loose ground at the battery. Apparently jiggling the pto and/or travel level switches was just enough to jostle the battery and loosen/remake the battery ground connection. I found it when I started to take the battery out and the ground bolt wasn't tight. I cleaned the connections and it is better now then ever.
Doesn't sound exactly like yours, but may not hurt to double check.
 

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As a test only for trouble shooting,, to convince yourself if it's in the safety switch,, You can use a jumper wire, from battery negative, to the small negative post of the solenoid. (that's where the safety switches all end up). If tractor starts up,, well it is in the safety switches. Once complete with your testing,, remove jumper wire. Note,, using a jumper wire, bypasses all safeties,, so first thing to do,, is to put the rear diff,, into neutral.

As well, with a test light,, clip to the positive post,, if you were to stick the needle onto the solenoid negative post,, if all your safety's are working correctly, the test light should turn on, if it doesn't,, jiggle the clutch lever,, and see if you can get it to come on,, if it does,, then it's the one on the end of the clutch lever. The safety switches,, should start by getting the frame ground, at the bottom of the travel lever,, (that's a perfect spot for rust to build up, and ruin that continuity,,,
 

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Discussion Starter · #5 ·
Thank you for the quick responses. I am heading out to the tractor right now with your suggestions in mind.
I'll keep you all posted on any discoveries.
 

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My tractor was manufactured in 1978, and there are no safety switches anywhere on this machine. I always wondered why the wiring had been redone. Someone had obviously removed all the safety devices. I've been relying on the safety mechanism between my ears all this time.
 

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My tractor was manufactured in 1978, and there are no safety switches anywhere on this machine. I always wondered why the wiring had been redone. Someone had obviously removed all the safety devices. I've been relying on the safety mechanism between my ears all this time.
I like were your heads at.

I've been relying on the safety mechanism between my ears all this time

bigman :thumbup:
 

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Discussion Starter · #8 ·
Here is an update: The PTO and Speed Control lever jiggle tests with the key turned were 'no-go' but I performed the solenoid jumper wire test as suggested www_ca. and the 446 easily started up (so it appears that there is a safety switch issue ... but I haven't yet performed the lever continuity tests to determine which switch because of what I write in the next paragraph).

I then unhooked the jumper wire and rode the tractor around a bit to warm it up. I shut it down for an hour and then tried to start it again with the jumper wire again because I was considering at least getting some mowing done (being very aware of the lack of safety mechanisms) before diving back into the safety switch issue. This time it cranked well ... but would not start. I tried starting five more times and each time the cranking became weaker. There was no cranking on the 6th try. I measured the battery voltage and it shows 12.7v.

My electrical knowledge is marginal ... but I do have a multimeter and I am now researching how to test the solenoid.

Please note: There is a 30 amp fuse on the positive cable to the battery running to the solenoid. Since this fuse isn't shown on the 446 wiring diagram I assume this was added by a previous owner. The diagram does show a 20 amp fuse between the starter switch and the ammeter (but I haven't located this fuse yet). I also forgot to mention that the lights do not go on when the key is moved to the 'lights' position after the tractor is running.

The detective work continues and I am 'all ears' and always open to additional thoughts.
 

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Hi there. Also no expert...but I believe others have had similar gremlins from a bad or going bad key switch. The fact that you state the lights position doesn't work when running could also point to that as well. Just a thought...I'm sure others more knowledgeable will chime in shortly. Good luck.
 

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By some chance, is wiring to the headlights touching the chassis or hood? On my 4018, there is a wiring connector near the hood hinge; the connector was not inserted all the way and was able to make contact. Again, just a thought......
 

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Discussion Starter · #11 ·
Another update (and hopefully some progress!).
1- The solenoid appears to have no continuity in the coils when checked with a multi-meter.
2- All positions in the ignition switch have continuity (I thought the 'lights' position may have had an issue but it does not ... so I haven't solved the lights issue yet).
3- The PTO neutral start switch appears to be misaligned and not functioning as designed. Perhaps someone can verify this by looking at the photo below. My assumption is that the switch lever should be riding on the 'bulge' of the PTO arm assembly when in the PTO 'off' position. Since it is riding on the cylindrical part of the PTO arm it is always in the PTO 'engaged' position (and no grounding). Is this assumption correct? (I've got 5 acres of hay that needs cutting so hopefully I am on the right track to getting the 446 running again :mrgreen:) Here is the photo:
Automotive tire Motor vehicle Wood Bumper Automotive exterior
 

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When you crank the engine,, with the starter solenoid ground with the jumper from the battery,, as in above post,

With test light clip, clipped to battery ground,, does your test light turn on if you test the positive side of the coil? It should,, because when you turn the key on, or to start, it should turn on the wire that goes to the positive side of the coil so that it's receiving positive from the battery. Your test light should confirm that,, does it? If it does that, motor still doesn't start?
 

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Discussion Starter · #13 ·
I hope to perform your suggested test this weekend. Right now I have the solenoid off the tractor to clean the grime build-up on the terminal studs and cable lugs. I tested the solenoid coil continuity (with no cables attached) at the two smaller posts and found no continuity (I thought these posts carry the coil current ... but I am a beginner when it comes to the electrical side of things so I could be in error). I appreciate your suggestion and will follow through soon.
 

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(I tested the solenoid coil continuity (with no cables attached) at the two smaller posts and found no continuity (I thought these posts carry the coil current)

In testing your coil, you should have come up with some numbers,,

The Coil test procedure is on page 20 of this manual,, (In essence,, you take your tester and dial it over to the OHMS section, using the lower scales,, stick needles on small post negative and other needle on small post positive,,) This should indicate some numbers when you do this test,, (move your scale around,, till you find numbers showing up in the 3.5 to 6.0 range,) This test should indicate something for you,, anything? Next is the plug terminal to plug terminal,, this should indicate numbers as well,, (play with scale) what numbers do you get? Last test,, needle on one plug terminal, other to side of coil,, what do you get for numbers? ( nothing should happen, ie open circuit)

Anyways,, page 20 of this manual,

http://manuals.casecoltingersoll.co..., B48 Service Manual 965-0754_watermarked.pdf
 

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As I interpret the testing so far: The jumper from the solenoid small terminal to the battery negative has already proven the solenoid good. The engine cranked over with the jumper in place, replacing the safety switches. You have identified a faulty, mis-positioned switch. IMO, you should correct that before continuing.
 

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Discussion Starter · #17 ·
Thank you www_ca for the engine service manual link ... this is a huge help for troubleshooting Onan engine issues. I had the 446 operating manual and parts diagrams manual but I didn't realize there was detailed engine documentation to dig into.

Thank you Ray_Wilson_KC for verifying the switch misalignment.

Thanks Kenc for your thought on correcting the switch first. Initially, the solenoid didn't seem to be an issue because the jumper test did prove the solenoid to be OK. But after starting the engine and then removing the jumper and running the tractor for 10 minutes a second attempt at restarting was not successful with the jumper and it appeared that the solenoid did not provide any cranking power. I am surprised that the solenoid jumper worked the first time but not the second time ... so I thought I might was well investigate the solenoid as well.

Having a non-running tractor isn't exactly fun ... but I appreciate the learning experience.
 

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Discussion Starter · #18 ·
Here is the latest update:
Replaced the PTO safety switch with a new one. Tractor starts ... although it takes a few cranking attempts. Once running, I tested the battery voltage and was getting 12.7 volts ... same as the non-running voltage. Not good. So I tested the stator and had good voltage numbers (29-30 AC volts, if I remember correctly) coming out of it. When I pulled the cables from the regulator/rectifier to clean them I found that the ground wire slot was not mating with the ground tab on the rectifier because the tab was bent so far that it was riding underneath the cable connector housing plastic piece when inserted. The previous owner must have pulled this connector off at some point and not re-installed it correctly. I straightened the tab and made a good connection. I now get 13.4-13.7 DC volts when the engine is running at 50-75% throttle. No wonder the battery had minimal charge after using the tractor for an hour or two.

The 446 is still slow to start when not started for a few days ... but it does start. I cleaned the spark plugs but perhaps new ones are in order ... they look like the have run for quite a few hours.

Today I went out to cut 5 acres of hay. Got through 1.5 acres and then the idler extension spring broke (!!!) on the mower mule deck. The spring looks like it is 39 years old. So now I am looking for a replacement spring. The local hardware store has smaller and larger similar springs ... but not identical. So the search begins ... at least it is a mechanical issue.

Thank you for everyone's assistance and suggestions for getting the 446 running again.
..::Jim G.
 

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Check out Brian at Salem or Bill at Barneveld in our sponsor section. They have great service and pricing. Glad you got your electrical gremlins sorted.


Sent from my iPhone using Tapatalk
 

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Discussion Starter · #20 ·
Just quick thank you again for the helpful guidance to get my 446 running and cutting. I put it to work a couple of evenings ago cutting a couple of acres (please see photo). I do need to work on the PTO engagement system though because the lever likes to migrate out of the engaged position. Cloud Sky Plant Tree Grass
 

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