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Topic: Hydraulic pump belt tensioner, 99' ISC (Read 611 times) previous topic - next topic

Hydraulic pump belt tensioner, 99' ISC

I am having an issue with hydraulic pump belt longevity. I put a new Gates tensioner on in California and we drove to Texas no problem, but on the test drive during the front end alignment at Camp Foretravel, Wayne reported that the pump belt shredded on the test drive. I bought a new belt at Foretravel for double the Amazon Price, and after about 300 miles, the back of it is not looking very happy. The belt rides a bit close to the outside of the tensioner for my tastes, and I read the thread about using a metric bolt that fits tighter in the tensioner than the SAE version. I can't really see how that should make any difference, since if the bolt is holding the tensioner on to the mount tightly, the idler pulley should be parallel to the pump mount.

I did read on Barry L's thread that he found a spacer under his old tensioner, but I couldn't find any such thing on ours. However, it looks to me like there should be about an 8th inch more of the idler pulley exposed on the outside edge. I guess I'm going to need to make a spacer out of 1/8 inch flat stock... Has anybody else run into this problem?
Thanks, Don
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Don & Tys
1999 U270 3602 WTFE #5402
Xtreme Stage 1 w/Headlight, Step Conversion, etc.
2009 Honda Fit Sport with Navi
Freedom is NOT "just another word for nothing left to lose"... with apologies to Kris Kristofferson

Re: Hydraulic pump belt tensioner, 99' ISC

Reply #1 –
Don,

Spacer thickness will be limited by the need for the detent to firmly fit in the detent hole.  Note, in addition to misalignment, tension may also be incorrect.  Incorrect tension may be corrected by changing belt length and/or drilling a new detent hole in the bracket.

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: Hydraulic pump belt tensioner, 99' ISC

Reply #2 –
Our PO put a tapered shim under the tensioner to correct an out-of-alignment problem. I had to yell at the tech who didn't want it back in when we had to replace the unit in CA a couple of years ago. With that shim we get lots of miles out of the belts. I have never tried it without the shim but the PO felt it was necessary so...
Larry
1996 U295 36'
Build # 4805
Actually we sold it but just like to lurk

Re: Hydraulic pump belt tensioner, 99' ISC

Reply #3 –
I made a spacer out of some 22 gauge stainless steel sheet metal that was a slug from a hole that I drilled in my utility panel project. In addition, I also used a 10mm bolt in the tensioner (just in case...). I put my old looking new belt back on to try it, and it did sit a little farther from the edge without the engine running. But when I started the engine it seemed to creep out towards the edge even though the idler pulley looks perpendicular to the mount. I have to make some more precise measurements... I may make a 1/8" spacer to try it, but any more than that would make the locating pin too loose in the whole since it has a taper and is only about 3/8" long. The tension on the idler pulley seems to be fine... I really wouldn't want to make it any looser. The idler pulley doesn't bounce at all when the motor is running like it used to with the old one. The pump pulley and the drive pulley seem to be in good alignment, but the drive pulley does wobble little bit.
Don
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Don & Tys
1999 U270 3602 WTFE #5402
Xtreme Stage 1 w/Headlight, Step Conversion, etc.
2009 Honda Fit Sport with Navi
Freedom is NOT "just another word for nothing left to lose"... with apologies to Kris Kristofferson

Re: Hydraulic pump belt tensioner, 99' ISC

Reply #4 –
Don,

In what directions does the crank pulley have run-out?  Many times the auxiliary pulley can be adjusted to reduce run-out.
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: Hydraulic pump belt tensioner, 99' ISC

Reply #5 –
Not sure Brett... It just seems to wobble a tiny bit. I am going to delve into it more tomorrow. I don't have a dial indicator with me (No doubt it takes a good size breaker bar to turn that puppy over by hand anyway), but I will find a silver marker or some such and check it while it is running.
Don
Quote from: wolfe10 –
Don,

In what directions does the crank pulley have run-out?  Many times the auxiliary pulley can be adjusted to reduce run-out.
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Don & Tys
1999 U270 3602 WTFE #5402
Xtreme Stage 1 w/Headlight, Step Conversion, etc.
2009 Honda Fit Sport with Navi
Freedom is NOT "just another word for nothing left to lose"... with apologies to Kris Kristofferson

Re: Hydraulic pump belt tensioner, 99' ISC

Reply #6 –
No problems on ours with run out (same 270 as yours), but I have replaced both idler assemblies.  Both had gotten loose and the hydraulic idler was totally shot and bearing seizing up momentarily.
Dave and Nancy
1999/2013 U270 36' Xtreme
Motorcade # 16774
2013 Subaru Outback
KD0NIM

Re: Hydraulic pump belt tensioner, 99' ISC

Reply #7 –
Quote from: acousticart –
Not sure Brett... It just seems to wobble a tiny bit. I am going to delve into it more tomorrow. I don't have a dial indicator with me (No doubt it takes a good size breaker bar to turn that puppy over by hand anyway), but I will find a silver marker or some such and check it while it is running.
Don

If the serpentine belt pulley on the crankcase is held by separate bolts, use a board to steady and a piece of chalk to mark.  Mark high point (engine at idle). Turn engine off, loosen bolts and move pulley slightly.

You could also loosen bolts, keeping a little tension on them, start the engine and use a board to slowly move in-- when the high point reaches the board, the pulley moves over, minimizing run-out. Sounds crude, but have used it on several applications.

BTW, run-out and/or failing belt tensioner is VERY hard on all the accessory bearings that belt runs.

I have posted it before, but here is a good short video on belt tensioners by Gates Corp:
Failed versus a good belt tensioner.
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: Hydraulic pump belt tensioner, 99' ISC

Reply #8 –
FYI, after replacing our original idlers with two new Gates idlers (and reusing the concealed hydraulic spacer plate), our hydraulic belt does not vibrate at all, and our alternator belt moves a lot, but less than originally.