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Topic: Removing Hydraulic belt tensioner and Alternator (Read 1132 times) previous topic - next topic

Removing Hydraulic belt tensioner and Alternator

I'm following some folks advice to have the alternator overhauled at my leisure rather than in the boondocks and also put new bearings in the idlers.  Removing the alternator and the belt tension idler was no big deal.  The bearings in the idler seem to be okay, no grinding noise, play, etc.  Really wondering if replacing the idler bearings is worth it.  Didn't remove the hydraulic belt tensioner as it is pressed up against the pump pulley with some force without the belt on.  Seems like I would need to remove the pulley in order to be able to replace the tensioner.  Anyone done that?  The pulley has 6 bolts and a large nut on the pump shaft.  The 6 bolts appear to go into a coupling on the shaft.  The bearings in this idler also seem to be okay.  The coach only has 65K miles, but is 15 yrs old.  The idlers do jump up and down some when the engine is running.  Do you think I am wasting time and money to put new bearings in the idlers? 

The Leese-Neville alternator also has a label "14 volt 3 step 79000" on what I think is the cover of the voltage regulator.  Anyone know what that means?
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt

Re: Removing Hydraulic belt tensioner and Alternator

Reply #2 –
Here is a good video by Gates Corp of good/failed belt tensioner:

Failed versus a good belt tensioner.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Removing Hydraulic belt tensioner and Alternator

Reply #3 –
We replaced our two tensioners ourselves with new "sealed" Gates tensioners which are much improved over all other "open" tensioners. One new Gates tensioner doesn't hardly move and the other moves a little.

The hydraulic tensioner had a 1/8" flat spacer that I almost overlooked and if not re-used our hydraulic belt would not have tracked correctly. The spacer looked like it was part of the old tensioner could have been trashed with the old tensioner. I had to pry it off the back of the old tensioner.

Re: Removing Hydraulic belt tensioner and Alternator

Reply #4 –
I would like to replace my belt tensioners. Anyone have the part numbers handy? It is a 99 ISC. Thanks, Mark
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Mark and Tanya
Milton , Florida
US Navy Veteran (DV)
1999 U270 Special 40' CAI , 2015 Jeep Wrangler Sahara

Re: Removing Hydraulic belt tensioner and Alternator

Reply #5 –
Word of warning: everything was good on my coach till I was getting some service done and tech advised one of the tensioners was bad.  Replaced tensioner and went on vacation.  200 miles away the hydraulic fan pump puked out.  Lost three days waiting on retrofit parts with now required pressure bypass valve to come from NAC.  100 miles after that the alternator died.  Lost 2 more days waiting on Empire Freightliner to figure out how to hook it up so that it would actually charge (they didn't initially know what "externally excited" means).  I continued on my vacation across most of the USA and the Mojave desert waiting on the power steering to go (which thankfully didn't happen).  I am going to have the tension and alignment checked before another trip.  I will probably have the tensioners altered with new detents (about 1/2" slack) as per Brett Wolfe's instructions as the set-up on the 3116 in our application just keeps too much tension on the belt.  If it ain't broke don't fix it and even if it is broke think long and hard about it.
Dwayne Keith
1992 U240
3116/MD3060

Re: Removing Hydraulic belt tensioner and Alternator

Reply #6 –
Thanks Dwayne,
    I have a hydraulic pump idler that bounces a bit like in the video that Brett posted. I thought I would change it out but I have a new belt on it and I am not having any problems. Maybe I will hold off doing it for now.

Mark
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Mark and Tanya
Milton , Florida
US Navy Veteran (DV)
1999 U270 Special 40' CAI , 2015 Jeep Wrangler Sahara

Re: Removing Hydraulic belt tensioner and Alternator

Reply #7 –
The other cause of a "jumping" tensioner is a broken bracket-- a not too uncommon problem.  With the engine off, grab the belt that drives the hydraulic pump and pull on it hard.  Make sure the bracket that holds the hydraulic pump does not move.  If it does, it will have to be removed and welded.

And I look at it differently than Dwayne.  If the tensioner is bad (bounces) it is putting a lot of additional stress on the bearings/bushings by loading/unloading.  If bad I would replace it.  If it is too tight, as I posted a long time ago, drill a new tensioner detent hole.  VERY easy solution to too much belt tension.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Removing Hydraulic belt tensioner and Alternator

Reply #8 –
My alternator is back in the coach with new bearings and brushes.  According to the shop the bearings were a little dry and the brushes about half used up at 65K miles.  The 3 step label has something to do with the regulator internal wiring as to whether it is set up for over the road use or frequent stop and start use,  now a discontinued item.  Didn't find a tensioner at a price I wanted to pay, so reinstalled it, and put on a new belt.  It still bounces at idle or slow speeds, but at 1500 rpm it is steady.  The hydraulic belt idler bounces at both speeds, will change it.  When I was attempting to replace the AC compressor belt noticed that the clutch bearings are apparently shot as there is a lot of play in the pulley.  Something else to work on. 
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt

Re: Removing Hydraulic belt tensioner and Alternator

Reply #9 –
Quote from: Jerry Whiteaker –
...  The hydraulic belt idler bounces at both speeds, will change it.  ...

I replaced the hydraulic belt tensioner on our C8.3 with a new one ordered from FOT. It was bouncing. There was no difference that I could see between the performance of the old tensioner and the new one. I carry the old one as a spare.

Squealing in the hydraulic belt drive system was cured when FOT put on a new belt of the proper size.
J D Stevens
1997 U295 CAI 36' Build #5085
2002 Subaru Outback
Motorcade 16869
Bellville, TX

Re: Removing Hydraulic belt tensioner and Alternator

Reply #10 –
My hydraulic pump tensioner belt is a 6 rib'd belt (original as far as I know). The pulleys are 8 rib'd.
I recently repaced due to age (6 rib's belt ).

Do I need to get an 8 rib'd belt????

1993 with 6V92 engine
1993 U300, 6v92
build 4366
USAF retired, Flight Engineer, C124, C130
 ATP, A & E.  & ex AI

Re: Removing Hydraulic belt tensioner and Alternator

Reply #11 –
Quote from: J. D. Stevens –
Quote from: Jerry Whiteaker –
...  The hydraulic belt idler bounces at both speeds, will change it.  ...

I replaced the hydraulic belt tensioner on our C8.3 with a new one ordered from FOT. It was bouncing. There was no difference that I could see between the performance of the old tensioner and the new one. I carry the old one as a spare.


Next step is to check run-out of each pulley. Often, there is enough play in the mounting holes, particularly on the crankshaft pulley used on some engines that no tensioner can remove all the bounce.  I have been able to correct several of these "mis-installed" pulleys merely by using a piece of chalk to carefully mark the high point of the pulley (engine running at idle and slowly move the chalk in toward the pulley until it just touches the place with the most run-out.  Then turn off the engine, loosen the pulley mounting bolts just a little and push the pulley away from the high point.  Re-check run-out.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020