Sunstar front PTO testing and removal - MyTractorForum.com - The Friendliest Tractor Forum and Best Place for Tractor Information
 
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post #1 of 13 Old 04-28-2019, 09:03 PM Thread Starter
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Sunstar front PTO testing and removal

I thought I had a manual, but can't find it.

First attempt to mow the lawn yesterday revealed a front PTO that didn't actuate. Worked fine last season. Checked power to it, and there's power when the switch is activated right at the wire plug going to the PTO. Tried running a hot wire to it, and that didn't activate it, either.

It looks like it's obvious I'll have to pull it, so what is the procedure on a Sunstar? Looks like a single bolt holding on the 2 pulleys on the PTO output shaft, do I just remove the bolt, slide/pull the pulleys off, then just un-bolt the PTO?

What is the resistance check for this type of PTO?

Kind of surprised it might be bad, how often do these things go, and are they rebuildable?
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post #2 of 13 Old 04-28-2019, 10:45 PM
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Re: Sunstar front PTO testing and removal

Did you check the air gap of the clutch? If it is too wide the clutch won't suck in. Should be .012-.014"'
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post #3 of 13 Old 04-28-2019, 11:24 PM
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Re: Sunstar front PTO testing and removal

Those PTO clutches are pretty reliable, in my experience. Mowman1 is right that the air gap needs to be adjusted correctly. Warner says to adjust to .012" and that the resistance across the coil should be between 2.40 ohms and 2.90 ohms.

Yes, you remove the center bolt and slide the pulley off. Use an impact wrench or you can simply use a hammer and tap on a 5/8" box end wrench or a ratchet wrench.

I'll attach a copy of the Warner Troubleshooting Guide.

Gerald
Attached Files
File Type: pdf WarnerPTOClutchTroubleshootingGuide[1].pdf (195.8 KB, 13 views)
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post #4 of 13 Old 04-29-2019, 09:14 AM Thread Starter
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Re: Sunstar front PTO testing and removal

Wow, thanks for that document, G-1! Is it a Warner PTO on the Sunstar?
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post #5 of 13 Old 04-29-2019, 12:39 PM
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Re: Sunstar front PTO testing and removal

Quote:
Originally Posted by Old_fart View Post
Wow, thanks for that document, G-1! Is it a Warner PTO on the Sunstar?
You are welcome. Mine have Warners, I don't know about others. Does yours look like the one in the document?

Gerald
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post #6 of 13 Old 04-29-2019, 03:22 PM Thread Starter
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Re: Sunstar front PTO testing and removal

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Originally Posted by G-1 View Post
You are welcome. Mine have Warners, I don't know about others. Does yours look like the one in the document?

Gerald
Mine DOES look like the pics, except it has a 2-row pulley.

However, in Figure 1 that describes the resistance check, my wire going to the PTO is a SINGLE wire, unless there's another wire on the other side I didn't see. I assumed it got power thru this single wire and grounded thru the mounting.

If mine is correct and only a single wire is used, can I assume the resistance check is still valid, and I would just check across this wire and the mounting surface?
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post #7 of 13 Old 04-29-2019, 10:45 PM
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Re: Sunstar front PTO testing and removal

Quote:
Originally Posted by Old_fart View Post
Mine DOES look like the pics, except it has a 2-row pulley.

However, in Figure 1 that describes the resistance check, my wire going to the PTO is a SINGLE wire, unless there's another wire on the other side I didn't see. I assumed it got power thru this single wire and grounded thru the mounting.

If mine is correct and only a single wire is used, can I assume the resistance check is still valid, and I would just check across this wire and the mounting surface?
What is the model number of your tractor? The early Sunstars used a PTO clutch that had one wire coming out of each side. Later, they had two wires coming out of one side. I never saw one that had only one wire and used the frame as ground. Sometimes the wires will break at the point where they exit the clutch. I usually reinforce the wires at those exit points (with shrink tubing or elec. tape).

Gerald
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post #8 of 13 Old 04-30-2019, 11:38 AM Thread Starter
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Re: Sunstar front PTO testing and removal

Hmmmm, rainy and cold, I haven't looked to see the model #, but I'll assume it's the model with a wire on each side, I just need to look on the other side for the wire.

So the wire I DO see on the right has power to it when I hit the PTO switch. Does the other wire run to ground? Maybe that's the problem.....

I noticed when I first discovered the problem that the REAR PTO doesn't activate, either. Used to work fine. I haven't checked power to it like I did the front, but it now seems weird that BOTH PTOs would stop operating, unless it's a common problem.
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post #9 of 13 Old 05-01-2019, 12:32 AM
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Re: Sunstar front PTO testing and removal

Quote:
Originally Posted by Old_fart View Post
Hmmmm, rainy and cold, I haven't looked to see the model #, but I'll assume it's the model with a wire on each side, I just need to look on the other side for the wire.

So the wire I DO see on the right has power to it when I hit the PTO switch. Does the other wire run to ground? Maybe that's the problem.....

I noticed when I first discovered the problem that the REAR PTO doesn't activate, either. Used to work fine. I haven't checked power to it like I did the front, but it now seems weird that BOTH PTOs would stop operating, unless it's a common problem.
Sounds like you have safety interlock problem of some sort which is preventing the left side from getting the ground it needs to activate the coil (assuming you do have the model which has a separate left/right wire on your clutch). So, if you apply ground to that left side wire, and have +12V on the right side wire, the PTO should activate. You can do this with the engine off; just ground the left side wire, turn the key on and the PTO sw. on to get +12V to the right side wire. You should hear the PTO activate (click).

I'll attach a copy of the wiring diagram for early Sunstars (like one of mine, a 1691018).

Gerald
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File Type: pdf Sunstar_1691018_WireDiagram.pdf (497.1 KB, 6 views)
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post #10 of 13 Old 05-01-2019, 08:41 AM Thread Starter
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Re: Sunstar front PTO testing and removal

Quote:
Originally Posted by G-1 View Post
So, if you apply ground to that left side wire, and have +12V on the right side wire, the PTO should activate. You can do this with the engine off; just ground the left side wire, turn the key on and the PTO sw. on to get +12V to the right side wire. You should hear the PTO activate (click).
Gerald
Thanks for the diagram and sanity-check for the ground. I'll check continuity from the ground wire to the chassis, but do the jumper-check anyway straight from the +/- of the battery to the PTO. If it doesn't work then I'll go back to suspecting the PTO itself.

Thanks a million for engaging in this discussion. My frustration level on the day I discovered the PTO wouldn't activate was off the charts, as it was the ONLY day in a 2-week span that it wasn't raining and I had the time to mow. What also contributed to a bad day overall was that my OTHER, back-up tractor (Ariens S-16H) that had been purring like a kitten all year but was currently without it's deck installed, DECIDED TO NOT START THAT VERY DAY. Traced it to a suddenly non-functioning fuel pump (Kohler K341 engine), but that was my last shot, and now the grass is 10" tall and no dry weather in sight.
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post #11 of 13 Old 05-22-2019, 12:04 PM Thread Starter
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Re: Sunstar front PTO testing and removal

OK then! So I checked ground on the PTO ground wire with the key on and the PTO switch engaged....no ground.

Then I pulled the sidecover off, cleaned the VERY nasty and corroded Insterlock plug connection, cleaned the PTO switch plug, then re-plugged everything and check resistance of the PTO itself per the manual G-1 provided. Good range was 2.4 - 2.9 ohms, mine checked 3.0 ohms.

But I started it anyway and hit the PTO.....wait for it......and it worked! The rear one works now, too!

So it came down to basic maintenance and the interlock plug connection, which G-1 suspected. I'm happy now!

I'm still mildly concerned that the coil tested out @ 3.0 ohms, but as long as it actuates I won't investigate further.

And, now I'm familiar with my PTO wiring!
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post #12 of 13 Old 05-30-2019, 01:12 PM
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Possibly the additional resistance could be due to remaining corrosion in the plug. You'll get a small amount of voltage drop in the connector but doubt its a problem.

If I were you, I would consider using a silicone dielectric grease*in the future to help kerp out moisture and prevent corrosion.
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post #13 of 13 Old 05-30-2019, 07:44 PM
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You stated that you couldn't find your SunStar manual. Didn't mention which model you have, but here's where you can get one for an 18 and 29 GTH series.

https://www.manualslib.com/manual/15...th-Series.html
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