Can I test the amps from my alternator like this?

[rsmith02184]

yes, that is the dynamo. the regulator looks different, mine has wires.

i will call the shop and have them look at it.

thanks again

just curious though: what do you think would cause the engine to shut down when I disconnect the battery positive terminal?

 

[Soundguy]

electric fuel pump? key off solenoid orifice valve? could be lots of things on newer machines.

older diesels didn't shut down till you pulled the kill cable on the IP...

soundguy

 

[jinman]

just curious though: what do you think would cause the engine to shut down when I disconnect the battery positive terminal?

What Soundguy said and also the possibility that your dynamo/regulator is not working. I think you are maybe slowly draining your battery or the regulator output has so much AC ripple that you need the battery attached to keep the AC superimposed on the DC level. If relays start chattering and solenoids get AC instead of DC, all normal logic is pretty much overridden. I don't know if that is what is happening, but I suspect a high AC ripple is making it out of your VR, possibly due to a rectifier diode going bad. I know it's a new VR, but you said it was getting very hot. I would expect it to get warm, but not hot enough to burn me if I touched it and certainly not enough to make the wires hot. If this were normal, a lot of other JD 4100 - JD 4300 owners would be noticing similar symptoms.

 

[Soundguy]

yep.. hot wires are tellin him something.

too bad there is not an oscope near him..

soundguy

 

[Treemonkey1000]

With the DMM reading AC on the battery that is saying a rectifier maybe shot. A good O scope would show if the AC was flat topped and what sort of waveform is on the system. With the tractor dying when he removes the battery seems like the dynamo is shot or regulator...

 

[rsmith02184]

the only thing that makes me question whether it is the dynamo is when i take readings at the VR, they are entirely within specs on the AC scales. They are 28 VAC at low rpms to 53 VAC at high rpms.

could the dynamo still be shot even though it is putting out the correct AC volts?

 

[Soundguy]

if you could load it and check it and it was within spec, then the dynamo could be ok, with the issue being the regulator/rectifier pack.

soundguy

 

[jinman]

I think the dynamo is fine and the VR is overheating and going south because something is drawing excessive current. I think whatever it is, it is probably not the battery. Right now, my guess is either the starter solenoid has a short when it should be open or a glowplug is drawing excessive current. My guess is also that the new VR is now toast and you've had an expensive experiment.

 

[Soundguy]

time for a test lamp inline to see what wire is drawing current.. IE.. lamp out when you pull the short..

soudnguy

 

[rsmith02184]

well, like i said before, i have given this a good try but I am ready to admit defeat. I don't know nor have the tools for the tests that you are recommending.

so here is my plan: I want to mow a few times before I send the tractor to the shop. I am planning on disconnecting the alternator so it doesn't continue to heat up the VR. I will also disconnect all light bulbs that draw current when I am mowing (i.e. the PTO light). Hopefully I will be able to mow my entire 5 acres before the tractor dies. Then I will recharge battery using a battery charger.

Does this sound like an okay thing to do until I get it fixed?