Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 13, 2025 ...

Generator end bearing maintenance warning

June 06, 2014, 10:59:47 pm

I had heard that Powertech says that the single end bearing in the generator should be replaced after 2-years or 3,000 hours of use. 

They say this because the bearing replacement can be not expensive, but when a bearing 'goes' it goes quickly without much notice.  The main rotor has close tolerances to the coils and when the bearing breaks the insides are usually badly damaged and costs go from around a hundred dollars to many thousands of dollars.  A new bearing cost about $32 and brush assembly about $66.

I was told that changing end bearing is needed because when generator is sitting for a while, grease settles to bottom & top bearings can rust.  And that an often used generator can wait until 5,000 hours to change bearing.  I think the 2-year limit is because a generator that is not used may not have a very healthy bearing.

This brings to mind that not using generator may have serious consequences.  We came up with a new idea to prolong the life of the bearing:  touch the start button to crank the generator for a moment every day, to rotate the bearing.  We have a manual preheat and manual start button, so hitting start without preheat usually does not get genset running.  Others may have automatic button that gets generator running, which may complicate just trying to rotate the bearing.

Attached is a photo of our end bearing after removing metal cover.  I included a photo of our generator compartment after installing new insulation over the original thick sound absorbing foam.

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Re: Generator end bearing maintenance warning

Reply #1 – June 06, 2014, 11:43:08 pm

We have something over 17 years and 3500 hours on our PT 10K. I assume the previous owner never changed the bearing. Our generator runs at least 30 minutes every month. When we travel, it usually runs a bit every day.

Thanks for the information. It may be prudent to do some maintenance on the "real generator" part as well as on the Kubota diesel engine part.

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Re: Generator end bearing maintenance warning

Reply #2 – June 07, 2014, 07:09:03 am

Thanks for the information Barry.  I'm wondering how involved the replacement of the bearing and brushes is? 

Would you be able to provide the product name of the foil faced insulation cover that you used?  It looks very nice and seems easier than removing and replacing all of the generator insulation.  Did you have to remove the generator from the bay to install it?

Also, did you completely remove your radiator overflow tank or just move it out of the generator compartment?

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Re: Generator end bearing maintenance warning

Reply #3 – June 07, 2014, 08:16:28 am

Barry, How do you remove the bearing ? I assume that the end plate has to come off, can that be done in the coach or is genny removal required ?
Gary B

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Re: Generator end bearing maintenance warning

Reply #4 – June 07, 2014, 09:09:12 am

On my '95 U320 they took three engine mount bolts out and could then rotate the generator enough so the generator end could be removed to change the bearing.

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Re: Generator end bearing maintenance warning

Reply #5 – June 07, 2014, 11:34:39 pm

We did not replace our bearing yet, but the job requires removing the large cast end cap, which is no simple task. The photo just shows the uncovered bearing, but bearing cannot be removed from the outside.

John, who did your bearing replacement? Good idea to rotate generator, because the slide tray may not extend enough. Can you tell us what steps were used to replace bearing and approx cost?

Our original thick sound foam in engine and generator compartments were in quite good shape, with some of the thin black covering cracked and torn off, which makes the underlying foam vulnerable. We did not remove any original foam, but did cover all vulnerable areas with foil tape to maintain the integrity of the foam. All surfaces in both compartments were covered with Coolit Thermo Tec Thermo Guard material with foil on both sides. In many areas, 3M spray adhesive was used to hold Thermo Guard in place, used a few screws under bed, silicone on bottom edge in engine compartment. A lot of foil tape sealed all edges and pieces. There are no places where criters, dirt, moisture can get behind Thermo Guard.

We purchased 4 rolls of Thermo Guard from Amazon.

We did not remove generator because there is full access to back of generator by removing bottom panel, allowing us to sit on ground with our upper body in the space behind generator, after sliding generator out. Found oil pressure switch was leaking oil, so we replaced the switch.

We decided to relocate the generator coolant overflow bottle in the space behind the headlight, where we previously moved our windshield washer container.

All engine mounts and radiator isolators were replaced, and all metal was painted with engine spray paint. We also replaced the fan and cut down the square metal shroud to keep it from damaging the right side foam insulation.

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Re: Generator end bearing maintenance warning

Reply #6 – June 08, 2014, 06:50:19 am

Barry,
Thanks for the response.  I'm going to try that out.

John,
Did you have an issue with the bearing or was it just changed due to a maintenance schedule?

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Re: Generator end bearing maintenance warning

Reply #7 – June 08, 2014, 09:44:44 am

 Morning,
No problem with the bearing, I changed it on the maintenance schedule in the PT manual.
The old bearing was still smooth but felt and sounded dry compared to the new one.
Cummings NW in Seattle did the work.
Can't remember cost but wasn't bad.
I guess you could get a labor estimate from any good generator shop.
PT should give good instructions on how to change the bearing and warn you about any problems you might encounter .
I think it's a good item to do because of the damage and expense you would have if the bearing failed. It's not likely you will ever do it again.

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Re: Generator end bearing maintenance warning

Reply #8 – June 08, 2014, 09:51:07 am

I'm not sure all PT generators require a bearing change at 3000 hrs.
Not all the generators they use are the same and may have different requirements.

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Re: Generator end bearing maintenance warning

Reply #9 – June 08, 2014, 10:50:21 am

Bearing noise (in most instances) will be a chirp that will let you know time has come to replace a dried out bearing.  Good thing to do is change it for peace of mind. 
I carry a spare sos I don't have to worry finding one when the time comes.  pc

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Re: Generator end bearing maintenance warning

Reply #10 – June 08, 2014, 12:44:59 pm

I seem to remember mention of a component inside the genset that has a tendency to detach and wreak havoc.  Brush holder perhaps?  Bearing change would be a golden op to nip that in the bud. 

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Re: Generator end bearing maintenance warning

Reply #11 – June 08, 2014, 01:14:25 pm

Feeling the end of housing can tell lots as to bearing condition also the temp/heat is also a big indicator.
Any roughness or temp uncomfy to the finger is a big flag.

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Re: Generator end bearing maintenance warning

Reply #12 – June 08, 2014, 11:42:22 pm

An ounce of prevention is wort a pound of cure. B. Franklin, circa... long time ago.
I don't know that I would wait for a dry bearing chirp, or any other symptom. That part about catastrophic failure & horrifically expensive in the same sentence got my attention.

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Re: Generator end bearing maintenance warning

Reply #13 – June 09, 2014, 01:51:41 am

With an aerospace background I am pro preventive maintenance. 

Not seen any posts regarding that particular failure and two friends are twenty and thirty year pro diesel coach techs say they have not either. 

Almost three thousand members here.  Anyone know of this issue?

Bob

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