PT won't start

[ponytug]

This is a little amusing.

I've been doing a lot of work on a corral for our horses. I laid out the grade (but that's another thread) and I've been trenching to get some subsurface drainage in. Trench a little, use the bucket to remove the spoils, repeat.

After some manual surveying, hop back on the tractor. Belted my self in. Put the key in the ignition, turn it, not even a click. I repeated it a few times, just in case the switch was dirty, but no luck. OK, must be the engine interconnect. Reseat it a couple of times. No luck.

Walk around the other side to check on the wiring to the solenoid. Hmmm. No solenoid. Gol durn coyotes must be getting real hungry!

OK it is after dark, but how can you miss a solenoid? Looking around, I realize it is hanging just off the floor of the tub. I think about holding it up, to manually crank it, but then I realize it won't have a circuit to ground to function. So, I leave it and hike up to call it a night and hit the showers.

About twenty minutes later, I start thinking about Sedgewood, and shorting and how bad it could get. I decide that discretion will result in an untoasted tractor for sure, so I hike down again, and take off the battery cable.

This morning, I stop by the auto parts store, and pick up a new "Ford style" pre-1981 starter solenoid. You only need a three terminal version, but the four terminal version is more common, and cheaper;

You don't need to connect up the "I" terminal, just the "S" terminal.

Three minutes later, we're back in business.

The old one had had a crack in the metal support that just got worse with time.

On Terry's advice, I added a rubber gasket behind it to reduce the vibration, but watching it, the solenoid certainly bounces around at idle. I'm not sure it will make much of a difference, but we will see.

Happy tractoring!

Peter

 

[cqaigy2]

Thanks for posting your fix! You might think about raising a few chickens, that will keep the coyotes busy and they may leave your pt alone.

 

[Bob999]

Peter,

Thanks for sharing. Could you explain the diference between a 3 and 4 terminal automotive relay? I understand one has more terminals--but why--what is the reason for the difference?

 

[ponytug]

Dear Bob,

Sure. "S" is for the 'start' terminal and "I" is for the 'ignition bypass' terminal. By applying power to the "S" terminal, you activate the solenoid relay and "I" gets power as well. Traditionally, this was hooked up to the coil, 'bypassing' the ignition, and generated a bigger spark, which helped get the engine to fire.

I think it is the "any port in a storm" theory of engine design. With better ignition systems, e.g. transistorized, breakerless, you get a bigger spark, and you no longer need to apply extra power to the coil. So you don't need a four terminal solenoid.

Napa sells a three terminal version, ST82 for $27.

(Unless you ask for the dual battery solenoid, which is $48, but sure looks like the same item.)​

The four terminal version is MPE ST82SB, $10.29...

You could probably even use the more modern Ford relay solenoid, but because of the close proximity to the muffler, I was reluctant to try a solenoid relay in a plastic housing.

I hope that this helps.

All the best,

Peter

Peter,

Thanks for sharing. Could you explain the difference between a 3 and 4 terminal automotive relay? I understand one has more terminals--but why--what is the reason for the difference?

 

[Charlie_Iliff]

Dear Bob,

Sure. "S" is for the 'start' terminal and "I" is for the 'ignition bypass' terminal. By applying power to the "S" terminal, you activate the solenoid relay and "I" gets power as well. Traditionally, this was hooked up to the coil, 'bypassing' the ignition, and generated a bigger spark, which helped get the engine to fire.

Peter

The 4th pole was also needed not only because the starter pulled the voltage down, but also most systems had a ballast resistor in series with the coil. Full 12V would fry the coils over time, so for ordinary running they had a resistor in series with the primary. The solenoid bypassed that for hotter starting spark.

Peter: My 1845 solenoid is on the starter, like a Chev. I take it yours is mounted away from the starter so it has a Bendix, right?

 

[ponytug]

Dear Charlie,

You've got it on both counts. (resistor, and solenoid) Actually, I have two solenoids on the engine. Here is the logic as I understand it.

The Deutz starter solenoid (at least in the 2011 series) is apparently really, really sensitive to getting 12.5V to engage the starter. Apparently the long circuit path (over thin wires) lowers the voltage enough to keep the Deutz starter solenoid from functioning reliably, so PT added a second solenoid (the "PT solenoid") mounted on the engine about six inches away from the starter, so that the Deutz starter solenoid would have a high enough voltage to function. They are both just below the muffler.

I have attached a photo, so that you can see the layout. Basically, the battery is connected directly to the starter, a lead comes off of the starter to the PT solenoid, which is controlled by the ignition switch at "S", which then applies the full voltage back at the Deutz starter solenoid, which engages the starter to crank the engine. Is that clear?

All the best,

Peter

The 4th pole was also needed not only because the starter pulled the voltage down, but also most systems had a ballast resistor in series with the coil. Full 12V would fry the coils over time, so for ordinary running they had a resistor in series with the primary. The solenoid bypassed that for hotter starting spark.

Peter: My 1845 solenoid is on the starter, like a Chev. I take it yours is mounted away from the starter so it has a Bendix, right?

 

[Bob999]

Dear Charlie,

You've got it on both counts. (resistor, and solenoid) Actually, I have two solenoids on the engine. Here is the logic as I understand it.

The Deutz starter solenoid (at least in the 2011 series) is apparently really, really sensitive to getting 12.5V to engage the starter. Apparently the long circuit path (over thin wires) lowers the voltage enough to keep the Deutz starter solenoid from functioning reliably, so PT added a second solenoid (the "PT solenoid") mounted on the engine about six inches away from the starter, so that the Deutz starter solenoid would have a high enough voltage to function. They are both just below the muffler.

I have attached a photo, so that you can see the layout. Basically, the battery is connected directly to the starter, a lead comes off of the starter to the PT solenoid, which is controlled by the ignition switch at "S", which then applies the full voltage back at the Deutz starter solenoid, which engages the starter to crank the engine. Is that clear?

All the best,

Peter

I think the older 1011 Duetz is quite sensitive to a voltage drop as well. there have been a number of posts on the subject where people, including me, have had starting problems when the voltage dropped. It is good to see that PT has recognized the problem and installed a fix. Hopefully your post will alert PT that they still need to improve the bracket mounting the solenoid!

 

[ponytug]

Dear Bob,

If you have starting issues, it looks like the fix is pretty easy. If you do it yourself, I'd put the solenoid on the wall of the tub. You can look at the photo above to get wiring layouts.

The bracket is made by the solenoid manufacturer. Both solenoids look nearly identical. Short of relocating the solenoid to some place with less vibration, I don't know that there is much PT can do. I thought of adding a piece of angle iron on the inside, but bracket is reasonably hefty to begin with. Actually, I'm surprised it failed. Looking at it, it is clear that the crack has been there a long time, so I don't know whether it was a manufacturing defect or fatigue. But I only have 112 hours on the PT, so I lean towards the former. Terry didn't seem to surprised by the failure, but he's a pretty low key guy.

As I think back on it, I did hear a funny metallic vibration noise several days ago. The last time I heard something funny, the engine cowl linkage had come unbolted. (I added locktite and a couple of bellville washers.) I think I need to be more proactive about subtle changes in the sound of the machine.

All the best,

Peter

I think the older 1011 Duetz is quite sensitive to a voltage drop as well. there have been a number of posts on the subject where people, including me, have had starting problems when the voltage dropped. It is good to see that PT has recognized the problem and installed a fix. Hopefully your post will alert PT that they still need to improve the bracket mounting the solenoid!

 

[Charlie_Iliff]

Dear Charlie,

Actually, I have two solenoids on the engine. Here is the logic as I understand it.

Peter

Peter:
A couple of years back, I modified my 1845 to put in that second solenoid. There's probably a post somewhere in the archives. The problem actually recurred a couple of years later, even with the solenoid, but seems OK after I ran a new wire down from the switch. As usual, I'm not quite sure I've identified the problem accurately, but I seem to have fixed it.

 

[ponytug]

Dear Charlie,

I didn't find it when I did a quick look, trying to find the brand and type; I will look again.

Given that I have found dirt in the engine connection harness and dirt in the switch both impact starting performance with the solenoid, I'm not surprised that you have had problems since you have way more hours on your machine than I do.

All the best,

Peter

Peter:
A couple of years back, I modified my 1845 to put in that second solenoid. There's probably a post somewhere in the archives. The problem actually recurred a couple of years later, even with the solenoid, but seems OK after I ran a new wire down from the switch. As usual, I'm not quite sure I've identified the problem accurately, but I seem to have fixed it.