Engine GX630 high voltage

Hello,
New to the Forum and thanks for sharing your knowledge.

I installed the Honda GX630 engine in my neighbors John Deere 318 2 years ago. Its been trouble free until a few weeks ago. He first had a dead battery and replaced it, mowed his yard but the battery warning light remained on. He brought it over and we found the diode burned open. We replaced diode and checked voltage at battery while operating. Voltage while at idle with lights and PTO off steady 14.5VDC. As you turn on lights voltage would jump up to 16VDC, Next turn on PTO and the voltage would jump to 17.5VDC. The diode would get pretty hot to the touch. He went ahead and mowed his yard and by the time he was done it had split the shrink tube open that enclosed the diode. Checked the diode at that point and it had failed by showing continuity in both directions with meter. Ordered and replaced diode and voltage regulator. Installed new diode and regulator. Conditions are still the same. At idle the voltage remains at 14.5 and never drops. If you apply any load the voltage will remain high.

Stator info No resistance to ground
.2 ohms between conductors.
AC voltage from stator while operating at idle no load (lights off PTO off) 34VAC
AC voltage from stator while operating at full speed no load. 68VAC

AC voltage from stator while operating at idle with light on. 22VAC
AC voltage from stator while operating at full speed. 45VAC

Again thanks for your input. Any advise is appreciated.

Regards,
Jim :thumbsup:

jimsozone said:

Hello,
New to the Forum and thanks for sharing your knowledge.

Click to expand...

Welcome.
I got a feelin' you may well know more than I on this topic so
in the sport of batting ideas around, try this on

Stator info No resistance to ground

Click to expand...

Infinity, yeh?

.2 ohms between conductors.
AC voltage from stator while operating at idle no load (lights off PTO off) 34VAC
AC voltage from stator while operating at full speed no load. 68VAC

AC voltage from stator while operating at idle with light on. 22VAC
AC voltage from stator while operating at full speed. 45VAC

Click to expand...

... nice work

Given the law which says voltage increases as a coil passes through flux,
directly proportional to the intersecting speed, what you are reporting is
"normal", yeh?
Sooooo.. I am wondering if from Day01 you have the correct alternator
for that engine..? Like 14.+ is already a little higher than 13.4 so maybe
the correct regulator trying to control a rogue alternator is at the core of this?

Your thoughts?

KK

The Honda GX630 was made with a 2.7A, 17A, and 26A charging coil. Here's an image showing all three; note the connector styles to I.D. the 17A from the 26A version:



Here are some test specs; measure voltage with engine running, measure resistance with engine off.



At 4,000 rpm:
2.7A = 110~130 VAC
17A = 60-75 VAC

Engine stop
2.7A = 1.95~2.93 ohms
17A = 0.18~0.28 ohms
27A = 0.17~0.25 ohms

Finally, check for continuity between each terminal and engine ground; there should be NO continuity.

* * If any resistance check is out of spec, or a terminal has continuity with ground, replace the coil.
* * If resistance check is good, but voltage was low, carefully inspect the flywheel. If flywheel is okay, replace the coil.

There are some additional tests to test charging current, load testing, and the regular/rectifier. If you are this deep, probably need to spring for the 151 page shop manual from Honda direct (free shipping):

Honda Power Equipment Shop Manuals on eBay
Honda Power Equipment Shop Manuals on Amazon

KK and Robert,
Thank you both for your input. It helps to put fresh eyes on a problem when you are stuck.

Robert, according to your attached diagrams, it has to be the 2.7 or the 17amp stator. Stator termination does not match the 27A stator. The AC voltages output closely match the 17 amp stator with exception to when I turn on a load the AC voltage drops.

I have to ask... As I'm testing stator output, I am not disconnecting from load. I have skinned the insulation back enough to connect a couple of meter probes.As I understand, if it doesn't have a circuit to discharge, the potential (voltage) will continue to increase and finally cause the stator to fail with a small puff of smoke. Just wanted to be sure I was checking my values correctly?

Again thank you both for your help! It's much appreciated. I will update or for sure ask for more input and help :smile:

jimsozone said:

KK and Robert,
Thank you both for your input. It helps to put fresh eyes on a problem when you are stuck.

Robert, according to your attached diagrams, it has to be the 2.7 or the 17amp stator. Stator termination does not match the 27A stator. The AC voltages output closely match the 17 amp stator with exception to when I turn on a load the AC voltage drops.

I have to ask... As I'm testing stator output, I am not disconnecting from load. I have skinned the insulation back enough to connect a couple of meter probes.As I understand, if it doesn't have a circuit to discharge, the potential (voltage) will continue to increase and finally cause the stator to fail with a small puff of smoke. Just wanted to be sure I was checking my values correctly?

Again thank you both for your help! It's much appreciated. I will update or for sure ask for more input and help :smile:

Click to expand...

As I understand it the coils do nothing without a circuit.
Putting a meter across coil output would fry the meter, likely.
It's a very very long time since my induction theory days so
I would proceed as you have...in parralel to load.

What would be interesting is to read what an inline current
meter would read, matched to your voltages at speed.
I do not know if a CT type induction meter will read
these coil outputs and mean anything...could be all over the shop.
But an inline meter after the regulator may give an indication of
circulating currents.

Reading Robert's input (and what a good thing Honda has in
Robert's interest here - go you Good Thing, HONDA!) I reckon you
need some tacho readings right now, carnt pass you my tool unfortunately.
Honda's specs are at 4K RPM. If you are anywhere near that then your
figures are well low so current must be well up and therein points to a
"loaded down" circuit, relected by the hot diode.
You got a short somewhere...chaffed wire in a loom or bad component
to ground, like 3K ohms to frame instead of infinity. No warm solenoids
or light casing frames?

You got a good one there, brother :confused3:

Thanks KK. Just bouncing things back and forth helps to ID where the problem is. I appreciate your input. I do have 2 meters. My Fluke is capable of reading DC up to 10 amps. I already started going through wiring looking for potential shorts. I should finish checking wiring out tomorrow after work If I don't find any shorts than I'll give it a go and read amps with one while reading DC volts with the other. I'll post findings. Thanks again for you guys and your support!

Regards,
Jim

jimsozone said:

Thanks KK. Just bouncing things back and forth helps to ID where the problem is. I appreciate your input. I do have 2 meters. My Fluke is capable of reading DC up to 10 amps. I already started going through wiring looking for potential shorts. I should finish checking wiring out tomorrow after work If I don't find any shorts than I'll give it a go and read amps with one while reading DC volts with the other. I'll post findings. Thanks again for you guys and your support!

Regards,
Jim

Click to expand...

....just to be safe?
Put a scaling resistor before your meter. You can always take it out if
the current is less than 10Amps.

Them there Flukes cost some bucks


I gotta go cut grass....happy days!!!

KK