Alternator Problem

[reelfishin]

I have a 671 ti detroit diesel that has a delco alternator. How is the best way to trouble shoot it on the engine. I know the amp guage is not working from the alternator. The engine runs fine all day long and will start the next day. I think the alternator is bad or the sending unit from the alternator to the guage is bad. I have tested the guage and it is good. I did that by using it on the other engine.
Wiring to alternator is good, I might have a bad connection at the alternator if the alternator is good. Thanks.

[seapower]

If you have a multimeter (digital preferred), connect the postitive and negative leads to the same terminal's on your starting battery. No need to attach at your aternator, it is just reading battery voltage too (this keeps you clear of the belt's). Start you engine, after you see oil pressure, raise your RPM to excite the alternator (this will allow the alternator to start generating voltage). If your alternator is charging you will see the voltage (DC) start to increase on your multimeter. It will go up in 1/10's of a volt until the charge is complete and the regulator will deactivate the field and the "charge" will cease. If you don't see a rise in voltage you could have a regulator failure or a failure internally in your alternator. If this is the case just as well take it off and to your local alternator shop. You can also just pull it off, carry it to the alternator shop and ask to have it bench tested. They will excite the field and see if it will start charging. If it charges on the bench test, you have a wiring problem (most likely a break or a loose connection. Pretty simple stuff, common sense mostly. Frank,SeaPower

[reelfishin]

Sea Power, you had me a little worried the first time I read your post. I thought you meant attach both battery terminals to the one terminal. Then I read it again and realized you wanted the meter attached to the battery pos to meter pos and battery neg to meter neg. Ok that makes sense. I am a electrician and do know how to use a meter, I will try what you said and report back when I find out the answer. I am suspecting a bad connection at the alternator going to the guage but until I can prove it I really don't know. Probably do it this week sometime or saturday. Thanks for the repy and time.

[Banshee]

check all your grounds toi make sure they are clean and tight, everywhere

[reelfishin]

Yes, I do believe in checking grounds. I had a problem on our windshield wipers and that was the problem. I knew I had power at the wiper but it was not returning. I checked the negative plate and the wire was held by one strand. I put a terminal on it and that solved the problem. I will take a look at it again to see it there are other problems there since I was there last time. I also will check the grounds on the meter , motor alternator etc. I have a few tricks up my slieve that I have not tried yet so I will see what happens. Definately do the test as described by Sea Power. That will tell if the alternator is good or not. Thanks.

[JD5652]

Ideally you want to see more than 13.7 volts but not over 14.1 volts......

[reelfishin]

I will be looking at the voltage when I do the battery test. We shall see what happens. Thanks.

[rugman]

do you have an amp meter or volt meter

[reelfishin]

I have a amp meter at the pilot station. I will be checking with digital volt and amp meter. I also have a swing meter that I use for testing capacitors and diodes. I have looked for a wiring diagram on how the alternator is hooked up to the engine etc. I really feel the problem is the connection at the alternator to the amp meter but that could be easily wrong. I have to prove it or find out what is wrong. So far some great ideas for testing given and I appreciate it. I will let everyone know what I find and how I found it out. To cold to do it now.

[reelfishin]

I must applogize, I do have a volt meter at the helm. I sure got off on the wrong track for sure. Anyway I went to the boat and worked on it today. The first thing I noticed was it was a volt meter and not a amp meter. I just stood there and called myself some stupid names.
Anyway the problem was a bad connection at the meter. I found the female plug had a big wide gap on one terminal and it did not make contact. I squeeze it together and it worked fine. Now I read 13.1 volts while idling. The voltmeter for the other engine is a little high. I may have to put a meter on it to make sure.
I still plan on doing the test that Sea Power said to do.
Thanks for all the imput.