Alternator

[rheavn]

I've determined that the coach engine charging system is producing no voltage. The alternator is a Lestek, Brute 270 which is a 270 amp alternator. The voltage regulator is mounted remotely in the stainless compartment on the right side of the engine compartment. My question is how do I determine whether the alternator is bad or the voltage regulator is bad?

Thanks in advance.......................

[tuga]

Steve,

I can't answer your question of how to tell, but about 3 years ago I noticed the same problem. It was the alternator! I had it re-built ($540) and it has been working great ever since. I might add that I could have purchased a new one for about the same amount.

I wish I would have bought a new one.

[prairieschooner]

good advice so far but not sure what engine you have. The 92 series or at least my 6V92 has a gear driven LEECE NEVILLE alternator and it is an expensive alternator. I went the Port of Los Angeles and was able to find an Electrical Shop there that had parts and could repair it right away. If you have this kind of alternator you should be aware that if the base of the flange shows leakage signified by an accumulation of wet dirt, you should repair the seal at the engine side. The seal is only about $15.00 or so and the Alternator is more like $300 to $450. I was able to find a new one on ebay and now carry it in my spares.
Good luck but with this expensive of an alternator I would most likely take it to a repair shop that I cold trust and have them look at it.

[encantotom]

the voltage regulator on mine is a delco 19020403. there is one on eba for 130 bucks.

my alternator is much much bigger physically and is oil cooled.

here is a simple way to see if the regulator is working or not.

from my meager experience if the alternator isnt working, it will not be putting out enough voltage. (before the regulator).




1 Turn on the multimeter and set it to read voltage. Connect the multimeter lead clips to the terminals of the vehicle battery. Connect the red lead to the positive terminal and the black lead to the ground terminal if they are colored as such on your multimeter, but polarity is not a particularly important issue here.


2 Start the engine. Let the engine run at its idle rpm and do not rev it up in any way. Take note of the voltage reading while the engine is idling.


3 Have a helper press on the accelerator and gradually increase the engine rpm.


4 Pay close attention to the voltage reading as the rpm increases. The voltage should steadily increase along with the engine until the rpm reaches about 1,000. At this point a properly functioning regulator will hold the voltage steady, with it not varying by more than 1/2 volt.


5 Add more electrical load to the system in the form of turning the headlights on high and running the air conditioner, all while your helper continues to rev the engine. The idea is to impose the maximum electrical load on the system. Monitor the voltage reading during this also. If the voltage changes more than the previously mentioned 1/2 volt, you most likely have a bad regulator. If the voltage holds steady, you can be assured your regulator is good. Then you can move on to testing the two other most likely sources of an electrical problem: the battery or the alternator.

[truk4u]

Another quick way to determine if the cause is the alternator or regulator is to remove the field wire at the regulator and touch it to a 12 volt source while having the positive lead of your meter hooked to the alternator. As soon as you touch 12v to the field wire, the alternator immediately ramps up voltage, confirming the alternator is good and the regulator is bad. Don't hold the field wire to 12v for very long, it just takes a quick touch and a spark is normal.

Just had to do that this week on the Prevost. The regulator for the D50 alternator was 87.00. Don't forget the jumper plate when changing out the regulator.

1270

1271

[rheavn]

Thanks Tom,
Just got back from a reliable "auto electric" guy who gave me the same instructions for testing whether my problem is the alternator or the regulator. He did say that since my coach has a battery isolator there is a chance that it is bad & the alternator & regulator is not sending any charging voltage because it is not recognizing battery voltage. He also advised checking to make sure the regulator ground was good. Tomorrow I'll conduct some testing.

[rheavn]

Thanks to all for your suggestions which were very helpful. Hopefully this post will help some one in the future diagnose their alternator problem.

The first symptom I noticed was the dash voltage meter dropped to about 11 volts. Newell had me check the voltage on the battery cable at the center post of the battery isolator. Voltage was zero. Newell tech felt it was the alternator.

The following tests will determine whether the zero voltage is the alternator or the voltage regulator. Remember my system has a remote voltage regulator. First test is the ground for the voltage regulator, which tested good. The voltage regulator has a four wire connector marked(left to right) "I", "A", "S" & "F". "A" should have battery voltage present at all times and it did. "I" should have battery voltage with the ignition is on and it did. The next test was to start the coach and jumper "I" to "F"--only connect for a second or two as you should see an immediate voltage jump, which could damage the batteries if left connected longer. My test results were negative, no voltage jump, so the alternator is bad. If I had seen a voltage jump when jumping "I" to "F" then the voltage regulator would be bad. If the battery isolator is receiving alternator voltage at the center post, but either one or both battery banks are not receiving charging voltage then the battery isolator is bad.

I posted some photos to help you visualize my explanation. Photo #1 is an overall photo. #2 is a photo of voltage regulator inside the stainless cabinet. Photo #3 is close up of voltage regulator and wiring harness--you can see the wire markings. Photo #4 shows the battery isolator.

Hope this helps someone...........................

[RussWhite]

I've never seen a dog that interested in an electrical panel before. Did he sniff out the problem? Russ

[prairieschooner]

OK so now off to a reputable shop. Be careful I went to a shop that had good reviews but our Alternators are not cheap. They took it apart and didn't have the parts to repair it, lost a few days but was able to get it back and take it to the Port. All was well because they had spare parts and were willing to use them, just a "heads up", try to find a shop that is familiar with your Alternator and has done them before.
just a suggestion

[rheavn]

Russ,
I should have known that you would recognize Project Cobra-4. Yes it is a voltage sniffer. It is in the early experimental stage, but showing some promise. The dog costume is used to prevent the Chinese from reverse engineering. You'll be the first to know when it is ready for production.

[Richard and Rhonda]

BTW,

You have a PennTex alternator. They have a decent web site for their products including wiring diagrams, troubleshooting, and parts lists.

[smagown]

Ive got the PennTex on my 97 also. Replaced it after the Austin mini rally, it was 985.00. Had my old one rebuilt for a spare.

They are very knowledgeable and easy to deal with.

Thanks,

[rheavn]

Got the alternator back from the shop. Problem was mechanical. The rotor retaining ring self destructed which caused the rotor to destruct. Replaced the rotor, bearings and brushes so we're good as new for $345. He turned it around in two days. Tested the voltage regulator and it was good. I questioned why I heard no noise or noticed vibration, but he said the brushes were holding it in place as it freewheeled. Hopefully I have fixed another problem that may have been happening since I purchased the coach.