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Topic: Can I replace my alternator? My answer (Read 542 times) previous topic - next topic

Can I replace my alternator? My answer

For novices like myself, I can now answer my own question:  Not without the assistance of Dave, a more knowledgeable neighbor.  With some encouragement from this group, I successfully removed the existing alternator by 1) disconnecting the chassis and house batteries, 2)  unbolting the alternator from the frame, 3) loosening the belt, and 4) disconnecting the four wires to the alternator from behind. With the alternator off, removing its pulley from the shaft was a problem.  I could not loosen it. Dave was easily able to use his (air) impact wrench to loosen the flange nut and put the old pulley on a the new alternator shaft.
Before installing the new alternator, I cleaned all four electrical connectors, each battery terminal, and each battery connector. The four wires were reattached first. Then I tried to install the new alternator by looping the belt over the pulley then re-bolting the alternator. Wrong!  Dave returned and first re-bolted the alternator. He put the belt over the alternator pulley. The tensioner was pulled enough to slide the belt over the smooth (non ribbed) water pump pulley.
Side note questions:
There was some corrosion on one house battery terminal. After eight+ years I'm  not sure what to expect. See photo.
Curiosity got the best of me and I unscrewed a small "compartment" on the side of the old alternator. See photo. It appears as if the two spring loaded connectors inside the "compartment" are meant make contact with the two knobs on the inside of the "compartment" door.  I do not see how to accomplish that so when the removed alternator is rebuilt it will work.
With the motorhome unplugged, the invertor off, and the 12V disconnect off, I disconnected all the battery cables. However, when I reconnected the cables to the house batteries (2 Lifeline GLP-8Ds AGMs bought 9/14/05 for $329 each) I saw a spark. The plus was connected first, then the negative, then the spark. No spark when the chassis battery cables were reattached. Why the spark? Are there enough loads from the LP detector etc that are on despite the open 12 volt disconnect?  Or do these old boys still have plenty of juice?
Bob

Re: Can I replace my alternator? My answer

Reply #1 –
Quote from: BobW –
However, when I reconnected the cables to the house batteries (2 Lifeline GLP-8Ds AGMs bought 9/14/05 for $329 each) I saw a spark. The plus was connected first, then the negative, then the spark. No spark when the chassis battery cables were reattached. Why the spark? Are there enough loads from the LP detector etc that are on despite the open 12 volt disconnect?  Or do these old boys still have plenty of juice?

Yes, I almost always get a spark when I reconnect batteries. I try to anticipate it and not get a "bounce". Lots of things running if the "salesman switch" (the house disconnect which is behind our recliner to the right as one enters our '93 U225) is not turned off; and a few things that are anyway regardless of where that switch is set.

As for the chassis (start) bank, this has a bunch of stuff running too but it depends upon the age of the coach. No salesman switch here.

For less spark next time, turn the salesman switch off. :)

Craig

Re: Can I replace my alternator? My answer

Reply #2 –
If you have the OEM diode block isolator, then there is no need to disconnect batteries (your step one). Measure voltage from the heavy wires to ground (both will read zero).

What you disconnected in the picture is the Regulator. It is either a fixed voltage or a "Three Step", which is what I have.
Reinstalling it requires pushing the springs and brushes back into the holes and keeping them in place with a small steel rod. I drilled mine out to 3/16 and use a drill bit to hold the bushes in place.

Any time you disconnect batteries, then reconnect, you will see a spark, not a concern unless it starts to melt and weld the connector.

Dirty battery connectors are bad news. The end of the cable in the picture is intended to be attached to a round post (like in your car), which will carry more current than the flat post on your battery. When you replace this battery, get one with the round posts to provide more boost when starting.

After seeing such a dirty battery connector, I recommend that you check and clean all your battery connectors, even the ground connectors under or near the engine. If after cleaning connectors, the engine spins faster when starting - you have done yourself a great favour.

 

Re: Can I replace my alternator? My answer

Reply #3 –
The rear view of the alternator looks like it needed attention one way or another.  pc

Re: Can I replace my alternator? My answer

Reply #4 –
Even with the salesman switch off and everything shut down, my inverter draws enough power(even when not actually running) to give a nice spark.  Only way to not get a spark is to have an actual battery disconnect in the off position when you hook up the house batteries. 

Re: Can I replace my alternator? My answer

Reply #5 –
And when it's 104 deg and you are wet with sweat get that sensation thru the extremities.. hate it when that happens.