Getting a Yanmar repaired

[tony123]

Wow Tom. Thanks for the thorough response and suggestions. I'm slow at all this electrical stuff. I do have a meter to use, but have never used it before. I'll try to follow your instruction tomorrow, but may have a few "how to" questions along the way.

My tractor does seem to be an "easy starter". And to confuse matters, the light was off for about an hour of operation tonight.

 

[tony123]

Tom,

I printed out your post and took it out to the garage with me.

I had to do some goggle searching to make sure I was using the multimeter correctly too.

First, 12.35 volts at the battery (not running) and 12.28v (while running). I'm surprised it was still so strong if I've been using it for 30-50 starts. This seems to verify no charging at the battery.

Second, wire temps were fine.

I'm attaching a photo just so you can verify that I'm at the right spot.

The blue wires (on the regulator side) did not give me any resistance measurements. But this could very well be my usage of the meter.

The white wires (coming from the alternator side) gave no voltage readings while running. This seems to show that the alternator is not giving any charge. Correct?

Again, thanks for your help.

Tony

 

[Tom_Veatch]

Yep, that's the right spot to take the measurements on the alternator. In fact that picture could almost have been taken on my tractor. Looks very similar. Based on your measurements at the battery, I'd agree that you are getting no charging current. The voltage across the battery with the engine running should be much closer to 14 VDC.

The voltage value at the battery really isn't that surprising. Except for starting, these tractors place very little demand on the battery except for headlights, etc. With an easy starting engine and only daylight operation, a fully charged battery could last through a suprisingly large number of starts.

The alternator is a permanent magnet device that doesn't need external excitation to product an AC output. If it's functional and being spun, it should be producing a voltage at the connector you show in the picture. But, was your meter set to read AC voltages? You were reading a DC voltage from the battery so unless you changed the mode setting on the meter before taking the alternator reading, the zero reading is to be expected.

You can verify that the meter is reading AC by taking a voltage reading from a wall socket. The voltage between the two vertical slots in a wall receptacle should register in the 110 - 120 VAC range. If you get that reading from the wall socket, and without changing the meter mode/range setting, still get zero VAC from the alternator, then I'd say the alternator has shot craps. However, it's much more frequent that the regulator goes bad instead of the alternator.

In either case, bad alternator or bad regulator, if indeed one or both is determined to be bad, I'd suggest converting to a 1 or 3 wire self regulating alternator. It's less expensive than replacing the OEM alternator (or regulator) and has, I believe, been done by several of the people on this forum. The biggest problem will be to find one that fits the available space without having to do a lot of reworking or fabricating bracketry. Here is one thread that talks about doing the replacement. And here is a list of threads returned by a search on "Alternator Regulator" in this forum.

BTW, if there is anyone lurking on this thread that wishes to contribute, please jump in! I am far from being an expert on this subject and can speak only in terms of my exeriences with my tractor.

 

[tony123]

aha.....I was still trying with DC. I just switched to AC and tested the wall socket at 112v.

This is not only a lesson in tractor charging systems, it is also a lesson in using a multimeter. Thanks for bearing with me. This is very interesting.

I can't test the tractor again until tomorrow. Sounds likely I'll find the regulator to have failed.

 

[blackd]

Tony123, I think you may need to get a longer battery cable and radiator hose to make the standard GM 10SI alternator to work.

 

[kenmac]

The only thing that I could add, would be take it to an alternator shop. Tom seems to have covered most everything else

 

[SailorBob]

You could also take the altenator to someplace like Autozone and they will test them for free.

 

[tony123]

Thanks for all the input.

I got home today and went out and used the multimeter the correct way.

I got readings from the alternator as follows:

13vac at 700rpm (idle)
21.5vac at 1500rpm
35.1vac at 2500rpm

Seems to parallel Tom's readings and verify that the alternator is doing its job.

I tested first at the connection closest to the alternator (shown in the above photo) and tested a second time at the connection closest to the regulator and got the same readings.

I get no resistance measurements from the regulator side.

Does all this determine that it is, in fact, the regulator?

If so, why are you guys saying go with a different alternator? because it's cheaper and includes the regulator? If it requires fabrication, I'm not too talented in that area. Tom, from your experience, is the likelyhood of loosing the next regulator high? I'm assuming you think thats a fair statement.

By the way, my regulator is labeled as RS 5101, which I don't see on Hoyes parts list.

 

[LMTC]

Thanks for all the input.

I got home today and went out and used the multimeter the correct way.

I got readings from the alternator as follows:

13vac at 700rpm (idle)
21.5vac at 1500rpm
35.1vac at 2500rpm

Seems to parallel Tom's readings and verify that the alternator is doing its job.

I tested first at the connection closest to the alternator (shown in the above photo) and tested a second time at the connection closest to the regulator and got the same readings.

I get no resistance measurements from the regulator side.

Does all this determine that it is, in fact, the regulator?

If so, why are you guys saying go with a different alternator? because it's cheaper and includes the regulator? If it requires fabrication, I'm not too talented in that area. Tom, from your experience, is the likelyhood of loosing the next regulator high? I'm assuming you think thats a fair statement.

By the way, my regulator is labeled as RS 5101, which I don't see on Hoyes parts list.

Electricity, particularly DC, is magic. Plain and simple. I have many multi and other meters, but I pay competent people to use them, because all I can do is turn the dials and look at them. Well, maybe not quite that bad, but it certainly can be confusing to a beginner. I've read (but not fully understood) several of these threads lately on alternator/regulator conversion, but if someone (or several someones) here can talk you through it and it saves $$, consider it. Just make sure you keep good notes in case you have to repeat or change it in the future.

If I am correct in recalling that you have a YMG2000, we have that regulator. It should have 6 wires to the plug; if it has 4 wires, you also need a conversion wiring harness with the regulator we and most other dealers carry. Your number is probably a mfr. ID number, which is rarely any help in looking up a part.

 

[Tom_Veatch]

Your results are close enough to mine to be considered within acceptable bounds of error. The only difference I see is that on mine, there was evidence of a high amperage current through the alternator (hot wires) even though there was no DC output from the regulator. That difference can be explained by assuming a different failure mode in the regulator.

What I did was first, make sure that I had good, low resistance connections throughout the charging system, e.g., battery terminals, regulator to ground, regulator to starter solenoid, and regulator to alternator. Then, I replaced the regulator which I have now done twice. That corrected my problem both times.

I've seen a number of posts dealing with this problem which, with my own experience, suggests to me that the regulator has a fairly high failure rate. Adding supposition to assumption, that suggests that either the regulator on these tractors is a "weak link" in the system or there is something on the operational side that I, and possibly, many of us, are not doing or are doing incorrectly.

The regulator that Wayne (LMTC) described is the type used on my tractor and probably on yours as well. The regulator is available from both LMTC and Hoye Tractors both of whom I can recommend, as well as, I assume, a number of other sources with whom I have no direct experience. Expect to pay a delivered cost in the neighborhood of $90.

If I run into the same problem and need to replace the regulator again, I'm going to give real serious consideration to converting to a 3-wire internally regulated alternator. (Google "1-wire Alternator") 3-wire instead of 1-wire because I'd like to keep some form of gauge or light indicator on the charging system. 1-wire is simpler to install but doesn't provide for any monitoring of the charging system.

From the picture you posted, you and I would both be facing a potential problem that I haven't yet solved to my satisfaction. We have an alternator that is very short from the centerline of the fan belt to the aft face of the case. And there is only about 1/2 inch clearance between the alternator and the water hose directly behind it. Any replacement alternator is going to have to be very compact to fit into the available space. Or there's going to have to be some fairly significant relocation of components. However, it's quite possible that I'm seeing difficulty where none exists. I'd sure like for someone who has actually done the conversion to post some pictures.