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Wednesday, May 11, 2016

Motorhome Repairs - Alternator and Isolator Replacement

As I promised in yesterday's blog...  there were MORE motorhome repairs to blog about.  I didn't want to add them to the blog until I was sure they were completely resolved.

As you know, we had alternator woes on our trip down to Florida and back.  Since that alternator was fairly newly rebuilt,  we were perplexed as to why it was not putting out enough amps. It was intermittant, sometimes 12 or 12.5... and other times 13 or higher. While down there, we first bought a kit to rebuild the brushes and regulator. Didn't help.  So then Steve ordered another alternator (rebuilt one) from Ebay and had it shipped to mom's house.  He installed that and it seemed fine, but about 100 miles into the trip home, it was acting funny too. We ended up running jumper lines from the four house batteries over to the chassis battery bank to keep the rig running. While we were driving, we have solar charging on the rooftop and also some of the route we had the generator running.  So between both systems, we had enough battery power to get home.

Well..... first off we had to remove the alternator and have it bench tested.  Remember..  I am Steve's Parts Girl while he is at work!

I ran it down to a local guy who rebuilt one before for us 2 years ago.  Sadly, he is going out of business and was only at the shop to sell off a bunch of old stuff to some guys coming in a truck.  I talked to him a bit and he said yes, he would bench test the one for us.... and hooked it up.  I got to watch and learn.  It was not putting out a charge.  He took off the rotor section to test on another machine and that was fine.  The regulator Steve just put in was shot as well as some other parts inside.  All the diodes were burnt right off, like over fried from something back feeding!

He said to go home and test our isolator.  That is an electrical unit that splits the power from the alternator and sends it either to the chassis batteries or the house batteries, but doesn't let them bleed over into each other.

In the meantime he would try to rebuild our alternator that afternoon. Even though he was going out of business, he was hanging around his shop for another truck to come by.  He also showed us a NEW larger alternator, 165 amp, that is brushless and is the newer type all the semi trucks run now. He offered to let us buy it at a great price if we wanted it.

Later on he called me to come back... he was unable to finish fixing our alternator as the regulator was shot, and he didn't have any new ones anymore in the shop.  But he gave us the other parts for free and didn't charge us a thing for trying.  Steve said to me over the phone to pick up the new bigger one he offered us, if the price was under $200.  Well, the guy settled at $160 with the promise to buy it back if it didn't fit or was the wrong type.  He even carefully drew on the case which wires went to which stud and if we needed an exciter wire or not.

The only problem we could foresee was that the case on the new one was about 2 inches longer than the case of the old one.  All the other tabs bolted in just fine, but not enough clearance due to a big air intake tube in the way.  Well, my brainy Steveio figured out how to cut down the boot of the air intake tube to shift it back 2 inches, move a big clamp, and now he had just enough room for clearance for the new alterntor!  What a guy!

The new one was in place and he did it so fast I never got a pic of it! But the new one is a Delco Remy in the $350-450 range!  So we did get a great deal!

At the same time, Steve tested our isolator. Yup... it was shot.  Using a voltage meter he should have infinity between two posts and swapping probes he should get no resistance.  Instead he got dead dead dead dead 0.

Now... this is late Wednesday, after putting in the waterpump so we had no time to get a new isolator.  Nobody locally carries them, so we had to place an order on Amazon to get one delivered in a few days.  So in the meantime the last thing we wanted to do was fry this alternator.  (the rebuild guy said that is how the others got fried, we went through three alternators in three months!)

Steve bypassed the isolator on the chassis battery post by putting all three wires onto one post just to hold them together.  He also disconnected the house batteries because they charge on their own by the solar power and don't need to be hooked up to the alternator for now.

At least we could go to Beaver Dam, Shopiere, and Beloit, WI and have our engine run smooth and not lose battery power.   And we did!

After my quilting shopping and friend luncheon on Friday, we drove on to Shopiere to spend the weekend in my friend's parking lot at her weaving studio... www.vavningstudio.com

(I will do additional blog posts about the studio visit on Saturday
and our friend's Anniversary Party on Sunday)

We did notice trouble with the inverter on board during the weekend... it would fluctuate, and then drop voltage output.  We turned it off and plugged into shore power for any 110 things we wanted to run during the weekend.

That had me really worried, because an inverter (a device that changes 12v DC power to 110V AC power) we use it to run things like our tv's, some of the lights, our coffee maker and grinder, curling iron etc.  We can do without them, but it makes it much more comfortable to have them on board. Replacing the 2000 watt inverter would cost more than all three other repairs we had done combined! The water pump, the alternator and the isolator are small potatoes compared to a 2000 watt inverter!

We got home on Sunday without incident and the alternator charged flawlessly.  Yippeee Skippeee!~ but we still had to install an isolator and figure out our inverter problem.  

On Tuesday the mail-lady brought Steveio his nice big box with his isolator!   
This is a Happy Man! 

The isolator has to be larger than the alternator's amp output.
So even if the old isolator had been good, we would have had to change it anyhow
to meet the higher output from the new alternator. 

Here is the old isolator... it is mounted on the wall in the engine compartment which is open to the dusty road and dirty diesel engine.  That is probably 20 years of accumulated dirt on it. LOL... If there was a better spot to relocate it to, Steve will think about it.  For now, he would just mount it where the old one is and use the same cables and wires.

 He held the new one over the area where it would go...
 just so I could take a pic! 

Imagine that.. a man reading INSTRUCTIONS! 
He doesn't do that too often.  
But he had to be sure or else ruin both the isolator and alternator,
and probably our inverter too? 

 He hooked up the wires and double checked and triple checked each one....
  •  2 wires on the left are to the chassis batteries and solenoid boost switch on the dash...
  •  (next post is skipped)
  •  the center post is the alternator and the engine clock. 
  • The far right post is for the chassis (house) batteries.

Steve then took out his voltage meter and tested while I fired up the engine. 
I was ready to turn it off if anything was wrong or arcing or heating up. 

Soooo we fired it up
and all systems are GO! 

What a beautiful sight on our Silverleaf readout display.!!!

Everything is working properly... even the inverter!  

Whatever was back-feeding with the old isolator is now corrected.
Whew....   we don't have to replace that now.

My next blog post will be about our visit with weaving friend Juanita and her studio in Shopiere, WI. 


  1. glad it all worked out with simply replacing the isolator

  2. Crikey ..... is there ANYTHING that man can't do?? Mum'd like to borrow him for a week or two.


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