1988 520H Fussy starting

[95 Truck 17]

Evening guys, I have a new question / issue. When starting this tractor, I get a solenoid click but not starter engagement. Now if I turn the key to run and let it sit a few seconds and turn to start, it will engage. Or if I turn key to run, let it sit a few seconds, then turn key off and go to start immediately, it will engage.

Seeing this tractor sat for about 15 years +\-, I went through and cleaned all the grounds. I checked all the connections and cleaned them and it still is functioning the same way. I jumped the starter and it engages immediately, so I really don’t think it’s the starter, I also checked the solenoid, it functions just fine. While troubleshooting I discovered that voltage to the solenoid is not reaching the solenoid. But if I let it sit and then turn the key the voltage will reach the solenoid.
 

Now, when I was looking at the wiring diagram and troubleshooting this issue I believe there are a few safety switches, such as a low oil or oil pressure and a few others to safeguard the engine. 
 I am thinking one of these safety switches is what is causing the daily. I am beginning to think it is the oil pressure switch. 
 

Any of you guys have a good understanding of the 520H starting circuit? What your thoughts.

[WHX?? 46,961]

Almost sounds like a safety switch but possibly the ignition switch? If you can get someone to hold the switch over to start and see what's at the solenoid when it's acting up and run the volt meter back to loss of power. When you say you can hear the solenoid click might point to solenoid contacts dirty? 

Prolly a dozen different ways to troubleshoot the problem but you want to do it when the issue crops up. 

 

[squonk 39,048]

Starter

[953 nut 52,049]

You may want to check the terminals on the back of your ignition switch, if there is corrosion that could explain the problem. With the key in the on/run position the switch will be carrying a small amount of current and warm up the "B" terminal where the voltage comes into the switch. Another potential point where the same thing could be happening would be the 20 Amp fuse that feeds the ignition circuit.

[gwest_ca-(File Mod) 10,532]

Oil pressure switch controls the oil light only.

Download this file to see a drawing for the start circuit only

 

[Zeek 2,284]

5 hours ago, squonk said:

Starter

 

I had the same issue on a Gravely. I thought it was the battery/ground/switch. I finally just tapped the starter with a hammer and it worked. I did it later on, I did the same thing, it worked. It never happened again.

Edited November 27, 2022 by Zeek

[lynnmor 6,836]

2 hours ago, 953 nut said:

You may want to check the terminals on the back of your ignition switch, if there is corrosion that could explain the problem. With the key in the on/run position the switch will be carrying a small amount of current and warm up the "B" terminal where the voltage comes into the switch.

 

Of course the fault could also be inside the ignition switch.

[953 nut 52,049]

Sure could be the switch but I always like to begin by checking the free stuff first. If they are good then the switch replacement would come next.  

Edited November 27, 2022 by 953 nut

[WHX?? 46,961]

6 hours ago, Zeek said:

 I finally just tapped the starter with a hammer and it worked. 

might be just dirty brushes/comutator. 

[953 nut 52,049]

21 hours ago, 95 Truck said:

I jumped the starter and it engages immediately, so I really don’t think it’s the starter

I sort of doubt that the problem is the starter as it works fine with a direct jumper. Have you run the jumper from the battery to the solenoid starter end? If the cable from the solenoid to starter is bad the starter will not turn over or will be slow.

Run a small jumper wire from the battery + to the small terminal on the solenoid, this should close the solenoid and run the starter.

[Jayzauto 89]

You can throw a LOT of Diagnostic Darts at this one.....As well as a lot of parts... Expensive parts.   OR get a DVOM or Power Probe and do some basic testing.   The lessons learned will be for life.   Learn Voltage Drop Testing.... INVALUABLE test... DO NOT USE OHMS testing..... very misleading.    These tractors are very old now.   I've found that just because a relay/solenoid "Clicks", is a very poor indication of function.   I find that most are indeed Bad.   But that can be confirmed with a DVOM, in 2 minutes.

 

On y tractors, I replace the battery, solenoid and make up all new cables.  Test all safety switches.   And never experience any more gremlins.

 

GLuck, Jay

[Zeek 2,284]

On 11/27/2022 at 2:48 PM, WHX?? said:

might be just dirty brushes/comutator. 

 

This particular tractor only had 175 hours on it at the time, so I'm not sure that was it.

[squonk 39,048]

You can have a dirty sticky brush in the starter and still work by directly jumping it because of less voltage drop due to fewer connections. Your 

"delay " in the starter activating with the switch makes me lean to poor connection either in the wiring or starter itself.

[squonk 39,048]

3 hours ago, Zeek said:

 

This particular tractor only had 175 hours on it at the time, so I'm not sure that was it.

That particular scenario is the exact cause of sticking dirty contacts inside a starter. Moisture forms rust and corrosion inside the starter and dulls up commutators, binds up arrmatures ect.

[95 Truck 17]

Thanks for all the input, I seen a good video on voltage drop testing. When I get sometime I will due some testing, I suspicious of the battery cable to solenoid 

 

 

[Zeek 2,284]

On 12/5/2022 at 3:54 PM, squonk said:

That particular scenario is the exact cause of sticking dirty contacts inside a starter. Moisture forms rust and corrosion inside the starter and dulls up commutators, binds up arrmatures ect.

Well, we are in humid Florida so I guess that could be the issue then.