Failed alternator?

[Robfike]

I am going to start looking at what happened to my charging on our return trip.
This is the backround:
First I started having a squeeling fan belt when I would accelerate from a stop. OK, I just thought I would need to adjust it when we got home. It then went to a squeeling about every 3-4 minutes as we went down the highway at steady speed. We turned off the fridge and it seemed to be better. The dash voltmeter showed about 13 steady volts at that time.
Second. We stopped for lunch. I checked the belts and they were tight, that's wierd I thought. The engine restart was normal, but now the voltmeter only showed 11 volts. I had purchassed a little plug-in digital voltmeter that goes into the cig lighter. It was jumping from 13.9 to 11 and then getting lower and lower. The dash guage just sat on 11. I then had the red light for the rear suspension come on. At that time I decided to fire-up the generator before we lost all the battery. After it was on line the suspension light went out and we proceeded home without any more problems.
I wish I had the digital meter in the socket when the squeeling was going on.
Is this something anyone else has experienced?
Where is the voltage regulator located?
Thanks, Rob

[jimmickle]

I believe that the voltage regulator is integral an generators of that era. You have to take the unit apart to get at it. When you go to put it back together, hold the brushes back with a round toothpick or 1/16 brass rod.

[steelbird312]

Rob, I've not had that trouble with a motorhome, however, I have a fair amount of automotive experience. From your description, I wonder if you have OLD belts. They could be tight, yet, if hardened by age, maybe glazed on the contact side, or, riding to deep in the v groove pullies. Then, when the regulator inside of the altenator calls for more production, the drag can make the belt squeals just as you mentioned. I would check my battery well, before I decided to change the alt.
So, if it were me, first the belt inspection (check for brittleness, or slickness on the contact sides, check that the belts are wide enough that they sit up in the v groove. By all means, the center of the belt should never contact the bottom of the v groove in the pullies.) Then next, I would check that the alt bushings are not in the process of freezing to the rotor. Then next, I would check the battery, probably by charging it up completely with a charger, and then taking it in the car to a local auto parts store and asking them to check it. If all is good so far, make sure ALL elecrical connections are clean and tight, including the ground straps (one to the chassis and one to the engine.) Then, if all else is good, drive back to the auto parts place, with the fully charged battery installed, and ask them to check the alt output.
just my thoughts.............

[87MH]

Rob:

I totally agree with Jim and Steelbird, but I think you should also check the voltage at the batteries with the air compressor both operating and resting.....I always get a "low voltage" while the compressor is running at startup.

The compressor is a heavy amperage draw and Airstream MIGHT have installed a way too small wire to it. there is always a chance that the compressor is about to go belly up and is drawing too many amps in it's death throws.....if the voltage is OK at the batteries with the compressor on, check the voltage at the compressor - you may be surprised at the voltage drop caused by the (long - long - long) wire.

The additive voltage drops on these units as they age caused by corossion, vibration, loosening connections, and other "old age" problems causes many of us heartaches from time to time.

Please post what you find.

Luck.

[Robfike]

Thanks, Will do

[Robfike]

I should mention that I have been having a flaky tach as well. This has been going on for about a month.
Thanks, Rob

[Robfike]

UPDATE
I finally got a chance to look into what was going on with the charging system Saturday.
I first removed the alternator and had it tested. Tested good. It is the late style Delco alternator with internal regulator.
Next I started going through the wiring checking for voltage. I found that I did not have any voltage at the "exciter" terminal on the isolator. This terminal gets it's voltage from the "ignition" group at the fuse block. This group of circuits all plug into the fuse block just above the "igintion" fuse. These are circuits that are powered when the ignition switch is in the "on" or "run" position.
I found that the fuse was blown. I replaced the fuse, turned the key to run and it blew instantly. I then pulled all of the wires and replaced them one at a time. The culprit was the step circuit. We had been having some problems with it going in and out as we drove. The step solenoid valve had shorted out.
Now with the step wire pulled, the charging system works as it should.
Now I just need to get a new step valve. (Vacuum step)

[Astrodokk]

I did a search and came up with this thread.

Last week I needed my MH for a small trip sp I plugged it into 110v and separately charged the start batt overnight too.

All started up fine in the morning, but as I was going home early eve I noticed my fan (plugged into cig lighter) was going slower and slower and fading, so looked at the dash voltmeter and saw it was at about 11. As I continued, it eventually rested at zero. I thought I had wired my cig lighter to the coach batts so I wasn't worried, but the vm showing that the start batt was not charging worried me.

I had this thing worked on by a pro only a few months ago with new belts, and the batts are about a yr. old. I will have the pro check out what was posted above first, but i think that it may be time to get a new higher voltage alt. What is an isolator and regulator? Where are they on an '81 454? Thanks.

[guy99]

What is an isolator and regulator? Where are they on an '81 454? Thanks.

The isolator connects the chassis (starting) battery and the house batteries ONLY when the alternator is producing voltage. This allows the alternator to charge both batteries banks when the engine is running. When the engine is off (no voltage from alternator), they are 'isolated' so that coach electrical use can't drain your starting battery and keep you from being able to start the engine.

The regulator tells the alternator how much voltage to produce. On my 84 it is built in to the alternator, I don't know about an 81.

[ralley]

Have your alternator output checked, or do it yourself with a voltmeter. It should be above 13 volts DC if your starting battery is low. See to it that your alternator belt is tight. Check the voltage across your battery isolator with the engine running--it should be the same as alternator voltage at the center post on your isolator and slightly lower at the other posts.

If you have a failed alternator, buy the one sized for your engine, or a little larger.

If you have a failed isolator, replace it. The diodes tend to fail as they get older.
Rob

[cooperhawk]

A few years back we were in Gettysburg at the battlefield and as we went to leave the engine wouldn't turn over. All of the batteries were run down and I had to find someone to give us a jump start. Since it is a diesel, it does not need a battery to run so we went down the turnpike. It started to rain and I was depressed to see the wipers slow down and then stop and the lights go out. I found a campground in the mountains and we spent the night charging batteries. It was obvious our alternator was out, but I wanted to get home to repair it here. I finially hit on the idea to drill two holes in the floor above the battery compartment and run two heavy wires through them and connect them to the batteries. Then I hooked my trickle charger to them in the coach and plugged it into the outlet, started the generator, and drove home. Worked just fine. When I got home I took off the alternator and had it rebuilt.

[Astrodokk]

Just had my mechanic inspect everything to find out why the alt. isn't charging the batt. Apparently the power steering pulley is twisted out of shape and the one belt belt came off that's attached to the alt. pulley. Since there are two belts on there and the one to the crankshaft was still on but INVERTED, my steering was not affected, so I didn't suspect anything to do with belts. Either the belts were put on wrong or I really think the PS pulley is out of whack. He will try to fix the pulley but I heard they're hard to get nowadays. Any advise how to get?

[Astrodokk]

As an afterthought, does anyone have a shematic on the belt order, or at least in writing how they go? IE inside PS pulley to outside crank, outside PS pulley to alt via AC etc... I don't know these things. Thanks.

[ralley]

Originally Posted by Astrodokk

As an afterthought, does anyone have a shematic on the belt order, or at least in writing how they go? IE inside PS pulley to outside crank, outside PS pulley to alt via AC etc... I don't know these things. Thanks.

Your mechanic should be able to sort this out. The belt runs should be straight--its easy to figure out. The pulleys are a standard size and should be available easily at a good parts store or junkyard--your mechanic may need to use a pulley puller to get the old pulley off and match for size. It ain't, as they say, rocket surgery.

A more important determination might be WHY your pulley is out of shape and how did it get that way?

Rob