| Author | Message | ||
| Vern Rainville (Vern_in_ri)
Registered Member Username: Vern_in_ri Post Number: 14 Registered: 1-2010 Posted From: 68.229.88.233 Rating: N/A |
I have a 1998 series 60 in my new coach, a Prevost. Yesterday, I started her up and the engine made a LOUD, continual noise that went away after about 15- 30 seconds. Later on in the day, I had my wife start her up while I stayed behind the coach. I noticed that the belts where loosened prior to me starting the engine. I know that there is a switch to loosen all the belts for ease of changing them. I did not touch this switch since I just bought this coach a couple of weeks ago and drove home over 1800 miles. I did open/ close the valve to see if it was working, and it was. Any thoughts of what I may look for? Vern | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 254 Registered: 10-2006 Posted From: 99.23.157.14  Rating: N/A |
Yes your aux air is leaking down and causing that. Do you have an on board aux air compressor. Does it cycle often? | ||
| Greg Roberts (Eagle 20) (Gregeagle20)
Registered Member Username: Gregeagle20 Post Number: 283 Registered: 4-2002 Posted From: 66.18.167.76 Rating: N/A |
I have seen systems that loosen the belts for starting and then pneumatically tighten them to running position after starting and air becomes available (possibly other criteria as well). I believe the design was intended to take off starting load and allow easier starting. Maybe yours was intended to do this as well?? | ||
| Mark Renner (Boomer)
Registered Member Username: Boomer Post Number: 208 Registered: 11-2006 Posted From: 206.58.200.38  Rating: N/A |
Joe is right. Around this vintage Prevost started using belt tensioners that were small Goodyear air bags, about 3" in diameter. They were supplied by the aux. air system, and have always been prone to leaking. If this is what you have you should always keep a spare bag or two with you, they are easy to change. Just spray them to find out which is leaking. Before starting your coach, check your aux air guage, if it is down, chances are the leak is from the belt tensioners. Yes the belts if not tensioned will really make noise. | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 255 Registered: 10-2006 Posted From: 99.23.157.14 Rating: N/A |
The regulator above the door is another potential leak point. So is the louvers for the radiator and its thermal switch. All converter installed air accessories will also be off the acessory air and can also drain that aux air pressure. step slide, air seat, pocket doors, toilet, air dump, ect ect ect Innitially you will find the easy ones with soap and water. Then they get a bit harder and I will begin to disconnect each house component from the air source and plug it and see if it affects the air loss any. If the air loss is causing the aux compressor to cycle frequently when camping it for sure creates a nusence. Usually the belts will not jump the pullys but they can. Either find the leaks or air the aux tank before starting. Who is the converter? | ||
| Bill 340 (Bill_340)
Registered Member Username: Bill_340 Post Number: 102 Registered: 7-2006 Posted From: 75.248.242.212  Rating: N/A |
Vern our series 60, in a prevost made all kinds of noise once in a while finall it didnt stop. made it easier to locate, was a pully/ roller bearing, it was under the fan belts. near the bottom of the belts. Sounded like the fan clutch was shot, it rattles terribly when bad.couldnt find one so whent to tractor supply found one similar and pressed it in to the original case, 5 years ago, still quiet............ | ||
| Vern Rainville (Vern_in_ri)
Registered Member Username: Vern_in_ri Post Number: 15 Registered: 1-2010 Posted From: 68.229.88.233 Rating: N/A |
Thanx for now all! I now have some starting points. Air leaks seem the most plausable place to start. I respond next week as I hope to have everything, "hopefully" under control.Vern | ||
| Ed Roelle (Ed_roelle)
Registered Member Username: Ed_roelle Post Number: 80 Registered: 3-2005 Posted From: 69.246.74.132 Rating: N/A |
Was it a squealing type noise? Your problem may not be due to loose belts tightened by the air bags. My belts are loose at start up on the left side of the engine, which drives the fan. The fan should be off at start-up, thus the looseness would not be a factor. If your battery was low, your alternator may have created a heavy load such that your alternator belt was squealing, until the load was reduced. Detroit Diesel changed the belt tensioner in the 1998 timeframe. They went from a mechanical, manual tensioner to a spring loaded tensioner. Also, you might check the idler pulleys and "feel" if the bearings are rough. Detroit Diesel does not offer replacement bearings because they want you to change to the newer design - $$$. However, there are other places to get replacement bearings. Ed Roelle Flint, MI | ||
| Mark Renner (Boomer)
Registered Member Username: Boomer Post Number: 209 Registered: 11-2006 Posted From: 206.58.200.38 Rating: N/A |
Although the fan clutch may not be engaged on a cold start up, the belts are still spinning the hub. Also, the drive belts from the crank pully to the miter box will not be tensioned if the tensioning bag is deflated, possibly making noise. We lost more than one bearing on the alternator auto tensioner over the years. It is a sealed bearing, and as Ed says, they want you to replace the whole spring loaded tensioner. Easy to get a replacement bearing from a bearing supply house instead of replacing the whole unit. If it seizes going down the road it will smoke the belt and when it parts company it is possible to also throw the miter box belts. Your first clue will be when the not charging light comes on. If your auto tensioner bearing has a lot of miles on it, I recommend installing a new one as PM. |