Alternator Problems. Any Suggestions???

[leedowney]

Hey guys. I have a 2000 Winnebago Journey 36G on a Freightliner chassis with the Cummings 275HP turbo diesel engine. Returning home today from our weekend camping trip, I notice the Volts dropping on my dash the closer I got to home. I turned off the dash A/C and was able to get the coach home. I have spent the last hour or so researching on this forum about battery and/or alternator problems. Both coach and chassis batteries are within a year from being new. One post on here said to check your alternator, start the engine and unplug the batteries. I just came in from doing that. The very second I unplugged the chassis batteries, the motor died.

Does this 100% for sure indicate a bad alternator? If so, how much do alternators run? And lastly, are they hard to replace and get to?

Any advice is much appreciated. Thanks guys.

[wa8yxm]

There are a few optiosn.. The alternator outputs usually via a fusible link, (Fuse) and that can fry if you draw too much current.. This can happen if you have very low batteries.

Locate the alternator, hook a volt meter to the BATT terminal (This will be the largest wire hooked to the alternator) now monitor that voltage both with the engine off and running. (NOTE Take routing the meter leads)

There is more but this is step one

Next depends on the alternator... SOME have external regulators, SOME need external power to the field.. I can't tell you how to go about testing those without hitting the book again.

NOTE: it might be the alternator drive belt too.

IF the alternator is bad, and you have the skills to remove it and transport it.. Try to locate a rebulider.. Can make a BIG difference in the repair cost.

[leedowney]

I removed the bed this evening and went in from the top. The alternator was very easy to access this way (see pic below). The belt is fine. Nice and tight. So I can rule that one out. It is the original alternator. 10 years old with 41K miles on it.

Question. You mentioned a fuse. Where would this fuse be located? Can a single fuse keep the alternator from working at all? At the time I noticed a drop in my volt meter on my dash, I was running the dash AC full strength. I was also running the generator which was operating the main A/C unit on the coach. It was 97 today and my wife and son were hot. This was the first time I've runned the rear AC and gen set going down the road. The dash AC only cools the front area.

[1ciderdog]

Lee
On a Safari motorhome I used to have there was an "exciter" wire to the alternator. That wire provided 12 volts to the alternator that it needed in order to produce produce power to charge the batteries. On that coach the wire ran from the isolator to the alternator and a fuse in that line was blown. I have no idea if this might help but you can take a look for a wire from the alternator that has a fuse.

[Martind4]

I think you're lucky that you had your generator running when the engine alternator failed. We had a similar problem last winter on our way to Florida, the engine alternator stopped charging and we were running on engine battery only. I noticed it soon enough and started the generator. Our Trik-L-Start charger provided just enough output to keep the engine battery at 11.8 volts and we were able to keep running. Then I mismanaged a fuel stop and ran low enough on fuel that the generator stopped. We were only about 2 miles from a Flying J and we were able to limp in with the engine battery showing 11.3 volts. Once we fueled up, I was able to restart the generator by using the MOM switch, recharge the engine batteries enough to get the engine started and we continued on our way. Our problem was a broken exciter wire on the alternator, which was easily fixed.

The Freightliner Help Desk (800-385-4357) can tell you the mfg and model of your alternator. Have the last 6 digits of you VIN# handy when you call. I agree with the previous post about finding a local alternator/starter rebuilder, it will be much cheaper than a new one

[leedowney]

I called my local Freightliner and they only sell new alternators for my model. The cost was $330. My parts guys gave me a huge tip though. He said they send their alternators right across the street and have them rebuilt. I called the shop and for $80, I'm going to have my alternator rebuilt tomorrow. Took the alternator off this evening and took it to Advance Auto. They checked it and confirmed it's dead.

I have one question for anyone who's change an alternator. The belt was very tight on the alternator and I was able after using a little muscle to get it off. Is there a tension pulley that I can loosen or a trick to make that belt a little easier to get back on? I am going to call Cummings tomorrow and see if they can give me a tip but I was hoping someone on here knew first hand.

Thanks guys for your help.

[Hooligan]

Lee: For the ISB engine, the drive belt has a tensioner that is spring loaded, some use a 3/8 and some a 1/2 inch square drive with a breaker bar or rachet. If you have the ISB Operation & Maintenance Manual, Section A gives procedures for releasing the belt Tensioner and to R&R the Alternator.
The tensioner must be pivoted away from the drive belt or the tensioner may be damaged...
Also good to diagram the belt routing before removing...

[Hooligan]

Lee: This diagram may help, the tensioner is on the left and pivots to slack the belt.. Diesel Database :: Drive Belt CTD

Hope this helps

[leedowney]

Thanks Hooligan. I am going to reinstall the alternator today. I had mine completely rebuilt for $80. They even painted it. Looks like a brand new one. I hope this one is as dependable as the one I just removed. 10 years and 42K miles ain't bad I guess.

Thanks again for the diagram. It will help a lot this evening.

[leedowney]

UPDATE>> Job is complete. Taking the alternator off and putting it back on, total labor time 1 hour. Buying a rebuilt alternator $80. Not paying my local dealership the quoted $620...priceless!

Wasn't a bad job at all guys and I know it was done right because I did it myself. Thanks for all your help and the diagram from Hooligan.

[Hooligan]

Lee: Super!!