It's Not Easy Being Green

[Jeffery Raymond]

For those of us Po' Folks who figured that a Series 60 was something that only the Prevost Prouds could afford, we might have thought that just having the newer engine was the be-all and end-all.

Waaalll, turns out that the first years of the Series 60 were not without some, well, problems.

The serpentine belt (very important) had problems in keeping a crown on the pulleys and there was some disagreement about belt tensioning. There was originally a screw-type tensioner. The idea here was to use some kind of a flapper gauge (very inaccurate) to determine belt slap. If the belt weren't completely set to the crown of the pulleys, side wear on the wide belt would result (bad).

So, there's an upgrade.

The oil refill housing is replaced, with the 2 silver pulleys and a spring-loaded belt tensioner. The mechanic here put chalk marks on the side of the belt prior to the test drive to insure that the belt was not rubbing on the site of the pulleys.

Just looking at it, I would guess that this upgrade in DD land is probably around $1200 off the shelf+labor. It is likely that the W.W. Grainger crowd could find some alternatives.

What this dealie does is regulate the tension on the serpentine belt accurately, even with increased heat, etc.

It's about a one-hour job to install the upgrade and you throw away the older threaded bolt tensioner (or send it to a friend).

Oh, a reminder, with the upgrade, you'll need a different belt than the one you used before as the upgrade kit requires a longer belt.

[ken&ellen]

My 8V92 has a quality belt tension-er. ( Kasey Kasem voice ) He is from a little town in upstate NY where he learn to play the drums at a early age. The educators in the late '50s and early '60s decided he was not college material and sent him to trade school where he became a tool and die maker, but when the large computer manufacturer in the town had a hiring freeze...he decided to go to college on an open admission policy. After completing his education he embarked on a career in the electrical field which lasted for close to 40 years. The rest is history on his way to becoming a Detroit Diesel belt tension-er. Rightee tightee--leftee loosey is his mantra!:D
Ken & Ellen

[truk4u]

Not on the pulley's oh great music person.. Bottom pulley is leftee tightee and rightee - loosee.:p

[dreamchasers]

My newly acquired 1995 Country Coach seems to suffer from exactly the same issue. I was a the Prevost Service Center in Fort Worth last week and one of the items I had done was the installation of a new serpentine belt. When I arrived back in Livingston, Texas (~250 miles), I noticed the new belt was wearing and slightly frayed on the outboard side.

I took the belt off and tested both idler pulleys, they seem fine. By laying a metal straight edge against the pulleys outboard side, then seem to be in alignment. Is their a procedure that can be followed to correct adjust the belt and solve the issue, or is the the purchased upgrade the only answer.

Is this upgrade a Detroit only obtainable item?

Hector

[Danss]

I had exactly same problem and finally gave up and got the Detroit dealer to install the upgrade. Was not cheap as I recall, but better than throwing a belt in the middle of nowhere. Good Luck, Dan

[Jon Wehrenberg]

The belt pulley alignment is critical. The coaches have two types of belt tensioners, a pulley that tightens using a screw jack (for lack of a better description) or a spring loaded tensioner like in the photo.

The part most likely out of alignment is the alternator. I do not know what techniques Prevost uses to insure perfect alignment, if any.

[dreamchasers]

Jon,

My alternator setup looks just like the picture you posted, with the exception that my has the "screw jack" adjustment for tension. I am guessing that by loosening the bolts under the alternator that hold the alternator in the 'alternator cradle', the alternator can be aligned by moving the alternator within the bolt holes slack. I plan to use straight edges for alignment of the pulleys. Then trial and error checks using the running engine.

When the engine is idling, I can see the belt running on the edge of the lower idler pulley causing the damage to the side of the belt. So I would expect to see the belt center on the idler with proper alignment.

Any tricks or hints before I begin.

Hector

[Jon Wehrenberg]

Hector, I wish I had the answer for you. My approach would be to see which way it needs to be adjusted, make the change, and recheck exactly like you plan to do. It would be ideal if you had sight lines available to you to see if everything is in alignment, but you can't really step off to the side to visually check it.

The critical part of the alternator is it not only has to align with the belt fore and aft, the axis of rotation has to be perpendicular to the belt otherwise more tension is on one side of the belt than the other, and that will make the belt try to run towards the side with less tension. Others have had the belt jump.

When it is running true it is going to stay centered within the pulleys. I think Jeff is of the opinion that the spring type tensioner is the answer, but all that tensioner is doing is applying the same pressure you can with the screw jack adjustment. There is no substitute for alignment.