[joel]

Gary,

We have had numerous discussions on this forum regarding fan clutches and how to lock a failed one.

No parts are needed to keep you going with a bad clutch and a quick search of the forum would have provided you with not only how to get back on the road but to diagnose the problem.

---

1999 XLV X-6872,  liberty #440

[Archived]

Don’t think I’ve ever heard of one lasting 1 year; that’s really bad. My first went to about 125,000 before starting to make nasty bearing noises…I replaced before failure. Second one now has 100,000 on it.

I would imagine it could be possible to eliminate the fan clutch. I had the series 60 (9 blade?) fan installed on my 1990 8V-92 without a fan clutch to improve cooling. The mod was blessed by Prevost at the time. The negatives of a fixed fan are a little more noise and, most likely, an increase in fuel consumption to turn it 100% of the time.

IMO, the most elegant solution would be to convert to electric fans. I’ve heard the new Prevost’s come so equipped and a Canadian company (europump.ca) makes a retrofit conversion kit for transit buses. I don’t know what it would cost, but there should be benefits of increased power delivery from engine and decreased fuel consumption.

[Archived]

Cooling has always been an issue with coaches and how Prevost has gone about providing sufficient air flow when needed to get up a steep long hill without overheating.

My first coach had radiator shutters and the principle in the use of the shutters was to reduce the load on the fan and thus reduce HP consumed. If you want to see how blocking air flow reduces the effort to turn the fan just stick your hand over the open end of the vacuum cleaner hose and notice the change in sound as the vacuum cleaner motor increases its RPM when air flow is restricted. The same motor can work much easier when air flow is stopped.

Then Prevost went with the fan clutches which have done the job of reducing fuel consumption, but to most of us the reduction in fuel usage has been offset to a great extent by the huge cost of replacing clutches.

Now new coaches are using electric fans. As far as reliability I guess we have to wait to see if they are an improvement. Superficially it would seem they have the potential to be more reliable, not only because a sealed electric motor generally has a long life, but because the system is significantly simplified with the elimination of the gear box, clutch, two belt tensioner air bags, fan belts and the associated pneumatic system to keep the belts tight.

But before running out to buy some electric fans I would be concerned about what might be involved in making the switch. If as has been discussed the engine driven fans do draw 30 HP that means electric fans have to have equal performance and that means a lot of power is required. To provide that power the coach has to have an alternator or an electrical system that can provide that power. I doubt if it requires a lot of power to cool the radiator on a level interstate so electric fans can be cycled on an off as needed, their speed varied or in some fashion call for only the power needed to maintain the engine temp.

I suspect however if a coach is used a lot in Colorado where it can frequently encounter higher elevations and steep hills any cooling fan system is going to have to be capable of moving a lot of air and my concern would switch from poor fan clutch reliability to the loads imposed on alternators and the electrical system, especially if the coach has OTR.

[kenneth]

Big trucks typically use an air operated fan clutch. The design is fail-safe in that a loss of air pressure to the clutch results in full fan operation. Another type of fan operation is via hydraulic motor. Both these systems are reliable and in my experience less trouble than what appears to be happening with the Prevost arrangement. So why an electric clutch?

[Harry]

Jon

appreciate the comments. I did lock out the fan clutch but somehow this had frozen the bearings or something. The fan would not turn locked or unlocked but was frozen.

gary

[Per]

That is very concerning Gary because it is an indication a vital device such as a fan can be rendered inoperative and with the result the coach cannot be driven.

I believe you are the first om this forum and others to indicate the clutch failure was a lock up of the fan and not one of fan engagement.

Were there any signals such as bearing noise, binding of the fan when rotated by hand, etc?

[Chad]

Jon,

the fan would not turn by hand, locked or not. Had not heard bearings or other “odd”noises. Like most problems showed up out of the blue. Not only was the breakdown a problem, concerning me is an $1800 part lasting one year and told there was no maintenance or things I could have done to prevent it.

---

1984 96" with 8V92TA

(remodeled Liberty Coach)

Greenwood, MO

[Fred F.]

The picture shows the coil wires mechanically destroyed (vs. electrically fried). Did the failing bearings take out the coil or vice versa. Could somehow road debris get wedged between the coil and the rest of the clutch?

[David]

Gary,

You are touching on a very sore subject with a lot of us owners. Maybe I am overly critical, but there has been a series of lousy choices made by Prevost for components that by anecdotal evidence really suck.

We all struggle with Ramco mirrors with a lousy chrome plating that begins to fail quickly, and if we ignore the lousy quality of the finish we cannot overlook how the mirror glass vibrates as we drive down the highway.

In the same vein those of us with EGR coaches have replaced very poor quality charge air coolers because they failed prematurely. This situation is made worse because a high quality intercooler with a very strong warranty is available for less money but apparently wasn’t acceptable to Prevost because the manufacturer did not provide the right paperwork. Where salt is rubbed in the wounds is that Prevost will supply the best CAC for replacement of the crappy original.

Then there is the fan clutch. As a veteran of two clutch replacements I also cannot believe Prevost cannot provide a clutch with a better life span. We pay full price for replacements that are just as lousy as the orignal and are not given any consideration when it comes to defraying the cost.

There are other examples but you get the point. I remember the good old days when Prevost really listened to customers, now they do not want to hear from us. Very disappointing.