Big Radiator Fan "HUB"

[JIM CHALOUPKA]

Has anyone worked on/rebuilt or replaced the fan clutch and shaft bearings on a series 60 engine.

I was checking things out this AM and since the air was down and the belt loose, I took it off and examined it with a magnifying glass and decided it needed replacing (small cracks and becoming brittle and worn). Checked out all the other belts and they are also being replaced.

The pulleys all look fine, wear wise and in alignment.

The idler pulleys spun freely, smoothly and true.

Spinning the fan pulley, well not so good, I am thinking, but don't really know. There is a certain roughness to the touch when spinning the shaft. Could this be caused by the clutch. There doesn't appear to be any lube fitting.

When the engine is running there is no (bad ) sound from the shaft. I listened to it with an electronic stethoscope and also felt nothing (bad) with a finger on the shaft end.

Maybe I am catching this just in time?
Maybe there is nothing wrong?
Any ideas anyone.

Also does anyone know will the fan and clutch shaft come off as an assembly without removing the radiator shroud?

JIM

[JIM CHALOUPKA]

I talked to Dave, a technical assistant at Prevost emergency service 1- 800-463-7738.
He offered the term growling to describe what I am experiencing in the fan shaft and said I am probably experiencing the preliminaries to failure. The shaft should turn smoothly.
He also said that to replace the entire unit assembly was the better way to go as a press and special pullers were necessary to rebuild the old unit.
When asked if the unit could be changed without removal of any other components, he said yes. First remove the fan from the unit by taking out the 4/5 mounting bolts and move it forward into the shroud and out of the way, then remove the clutch/shaft unit, add the old pully and reinstall all components removed.

Parts dept is closed today. I will order Mon and post back how the job goes.
It sounds like you could do this job by the side of the road, if you had the new parts. If your mileage is close to mine, check yours out, it's not difficult.

Feels funny talking to myself, but I guess there is someone out there:rolleyes:

JIM

[ajducote]

JIM,
You are not talking to yourself. The information is very welcome and please keep us posted on the price and the steps needed to replace it. Pictures are good....

[Kevin Erion]

I changed mine at about 112000, it was sounding bad! I have a feeling this is a common part to fail, and not very cheap!

[dreamchasers]

Jim,

After reading your post, I went out and checked mine. All OK.

I do appreciate all the details.

Hector

[PLSNTVLE2]

JC
Great post. I'll bet a lot of people don't think of checking the fan clutch as a maintainance item.
I twirl mine around once in a while. I guess it looks cool.

I know I wouldn't want my fan to fly off while crossing the desert.
Thanks for bringing it to mind.

[Jon Wehrenberg]

It is difficult to hear bearings going bad when the engine is running.

Jim is directly on target describing how he took the opportunity to do a little inspection work and find minor issues like the belt and the shaft bearing. By dealing with them now they are non-issues. Had he learned of the problem when the belt broke or the bearings seized it would have been more serious and he may have been facing a tow or a roadside repair.

There are several idler pulleys and belts that should be periodically checked. Not all coaches are the same because of the variety of alternator and AC configurations so there is not likely any specific advise that applies to all.

[JIM CHALOUPKA]

The fan clutch assembly Pt No 550634 new No (550837) ordered today @ $1108.95 ea.

JIM

[Joe Cannarozzi]

Do they have a rebuild kit for that?

[JIM CHALOUPKA]

I asked that very question of the parts guy, Tom, and he said no not as such, no kit. What you do is look at the blow out diagram in the parts CD or on line or in a hard copy of the Prevost parts book and pick out the parts pieces you want.
I asked do you sell many parts pieces for rebuild and his answer was "NO, when that unit goes it usually means the bus is down, by the side of the road or in the garage and the main objective is to get it up and running in the shortest time." He further acknowledged that a press and special tools were necessary for a rebuild. Tom said some customers rebuild units and keep them on the shelf for future need. He implied that this clutch assembly had a high sales volume and is a very profitable maintenance item for his Co..

All you guys better check your units and save yourself a breakdown.

JIM

[Jon Wehrenberg]

Jim,

Just to be sure, are you talking about noises from the clutch or the shaft assembly driving the clutch?

This is important because if the clutch (which free wheels at low engine temperatures) has bad bearings it can be locked to the driven shaft assembly and may not put the bus out of service.

If the driven shaft and its bearings fail that will disable the bus.

Also for those who may not be aware there are other bearings and idler pulleys across the face of the engine for other driven devices such as AC or the alternators which should be checked periodically. Those idlers can be serviced, usually by getting the bearing number off the part and pressing in a new bearing.

[Coloradobus]

JIM,

IS this growling noise they told you about audible from with inside the bus in the bedroom, or from standing outside?

[JIM CHALOUPKA]

Jim, it's not a noise per se, it is something that you feel in your fingers when turning the shaft by hand. No load. Belt off. Just spin the pulley by hand and then lightly feel the shaft as it turns.

JIM

[Kevin Erion]

Co. Jim, Yes, you will hear a growl if you stand near the Driver side Rad area. I am of the opinion that they will start to make noise and it will take some miles before they fail. What happens when they fail, I have no clue but might not be so good. Prevost Mira Lome had no less than 20 in stock. Why so many, maybe they fail a lot, just a guess!

[lonesome george]

Jim,
When first inspecting our coach one of the things I did was roll the cooling fan thru with the belt attached to get a feel for the thing, all was good.
After several short trips it started making a bit of noise so off it came. I'm thinkin just poke some new bearings in it, turns out to be lots more difficult than that. The bearings that were getting noisy are a double bearing arrangement, one inside the other, with the races built inside a flange. The part can be purchased from LINNIG Corporation. Tucker, GA 30084 ph 770-414-9499 for $250. but no stock and a 8 week delivery, so I requested air freight and the price was an additional $400. the clutch has two other garden variety bearings on the input shaft, add those in and the $1,100. new part starts to look better.
The replacement clutch has a different part number with some design changes, it looks like the bearings on the flange can be replaced without replacing the whole flange.
The maintenance manual says to wash the clutch with diesel fuel and rinse with water, DO NOT PRESSURE WASH THE CLUTCH. I DID and that could be what happened to the bearings and my $1,100 Lew bucks!
The new clutch makes no noise and has no vibrations that I can feel when rolling it thru by hand with or without the belt on.
Still Lonesome

[JIM CHALOUPKA]

Thanks for the info George.

Some guys pressure wash a lot. I have heard of fire alarms not liking the water either.;)

Were you implying that Linning Co makes the clutch assembly?

If they did not have stock, how did the next day air help you, or did I miss read your remark?

No matter how you look at it we got the shaft.:D
JIM

[lonesome george]

Jim,
Sometimes my crap is not to clear.
Linning Corp. makes the clutch and it is a nice piece of work and about the same price a air clutch for a truck but our's are two speed.
The 8 week delivery was for a standard ocean shipment from Germany for the part, the $400 additional fee was to have the part shipped by air to get it in a few days, I have no idea why the air charge is so high.
I gave up and ordered a new unit from Prevost.
I'm guessing that the part I needed is not stocked in the US because the unit has been redesigned.
I will never pressure wash the engine compartment again, Jon is spot on about using soap and a garden hose to wash the goop off.

[JIM CHALOUPKA]

My fan clutch assembly was delivered today and it is really a nice piece of work and that is something coming from a Machinist of 43 years.

Turning the shaft on the new one is like drawing a knife through soft butter. :)
The old is like drawing a knife through coarse sand. :eek:

I will take pictures and write up the job for those interested.

JIM

[Joe Cannarozzi]

The pictures I want to see are the ones where you rebuild the old one.
Get them by boat they will arrive in about the same time it takes you to get to the door;)

If the shipping expenses is not 400 how much are we talking about to do it with parts.

[lonesome george]

Joe,
The parts to repair my old clutch would be about $350.00 total if I wanted to wait for the boat. I don't know what the cost of parts would be to do a complete rebuild but some of the stuff in the clutch looks spendy.

[Joe Cannarozzi]

O/K you have successfully convinced me your screwed either way.

So all that added engineering and expense and complexity for an extra what 20hp over the "old style". Put another check in the win column for the antiquated 1985 model.

[Jon Wehrenberg]

Don't gloat Joe........Pay me now or pay me later applies here.

First, your fan is a big heavy steel one and on that vintage the weight of the fan was tearing up the 90 degree gearboxes so Prevost eventually came up with a plastic replacement. So folks with your vintage coach were spending money also.

But they continue to spend money. Any fan that is working uses horsepower, even when it does not have to be working. The fix for that was radiator shutters. If you want to know how much less power a fan uses when operating in a low pressure environment such as behind radiator shutters, put your hand over the end of a vacuum cleaner hose and listen to how much faster the motor spins. That increase in speed is because the fan is no longer moving air and the power to run the fan is greatly reduced.

Air shutters on our coaches went the way of the buggy whip when Prevost started stacking up cooling coils for fuel, and air so the solution to minimize fuel used to drive a fan was to install a fan with a clutch. I bet the fuel saved over time more than pays for any maintenance.

[truk4u]

I assume the new plastic one, which I have, is an improvement, but compared to a series 60 fan assembly, mine shakes like a big dog pooping a peach pit! I learned that from Jdub.... Brian even had to stop drill the plastic cover to keep it from cracking more. I do understand it's mounted in rubber and is suppose to vibrate.:(

[Joe Cannarozzi]

Yes Jon all true additionally if I had to guess I would bet that yours in low speed is driven 1 to 1 and in high speed it is in overdrive. Ya think? Jimmy will tell cause I know he will pull his old one apart.

[Jon Wehrenberg]

Tom,

If you shut your engine down from the rear while watching the fan and the gearbox it will make wonder how the assembly doesn't tear itself apart.

Now imagine how bad that thing was before the plastic fan was installed.

I had a steel fan on my old Liberty and as soon as I saw the difference in how much that fan shook I bought a new plastic one and got rid of the steel one.

[GDeen]

(never cease to be amazed at the experience and knowledge around here....)

[Ray Davis]

Is there a way to easily force the fan into high speed, while watching it from the back side of the bus, i.e. not driving.

I am having an issue where my in dash prodriver is indicating 206-212 degrees while driving, and it shouldn't be that hot. The analog dash gauge doesn't indicate that high, and generally I had always watched that until recently I checked the digital temps in the pro driver.

I want to track this down to see if there might actually be an issue. So, I'd like to somehow verify the operation of the fan.

Just as background the bus was completely serviced before I picked it up in October, and the coolant levels are fine.

Any thoughts on how to proceed, and test this?

Thanks,
Ray

[Jon Wehrenberg]

Is there a way to easily force the fan into high speed, while watching it from the back side of the bus, i.e. not driving.

I am having an issue where my in dash prodriver is indicating 206-212 degrees while driving, and it shouldn't be that hot. The analog dash gauge doesn't indicate that high, and generally I had always watched that until recently I checked the digital temps in the pro driver.

I want to track this down to see if there might actually be an issue. So, I'd like to somehow verify the operation of the fan.

Just as background the bus was completely serviced before I picked it up in October, and the coolant levels are fine.

Any thoughts on how to proceed, and test this?

Thanks,
Ray

I cannot get and keep my engine coolant temperatures hot enough and keep them long enough for me to get out and see the fan shift speeds. If I run it hard, get it really hot by climbing a hill, by the time I'm parked, get out and get to the rear it has dropped down in temperature.

So to answer that question, if I really really needed to see the fan speeds kick in I would do something I would not recommend, and that would be to cover the radiator fully or partially depending on the size of my gonads to watch the fan clutch kick in.

Since heat is the enemy of the engine I would want a solid gold way to know the engine temps so I could pull the blockage from the radiator ASAP if they ramp up.

To verify the coolant temps you say you have a dash gauge that differs from the DDEC readout on the Pro-Driver. Does your vintage coach have the coolant temp gauge in the rear? If so perhaps that could be the gauge to determine which is more correct.

I think the clutch engages in the first stage at 204, and then at 208 for the second stage. I also think the engagement temps are settable. I do not know that for sure and that needs to be checked with Prevost.

If I recall early Series 60 engines had the fan set to 215 and the temps were scaring those who previously had 8V92 engines and were used to seeing 180 degree temps. I think Prevost set the temps back. I may be all wrong on that because I am going by memory and I got that info secon d hand.

[Ray Davis]

I had heard a rumor that there was a way to remove or jumper a relay that would kick the fan to high speed, just to see if it's functioning. Obviously, that doesn't indicate that the fan IS jumping to high speed at the correct temperature.

I will have to look, I believe I may have a temp guage in the back of the bus, but I'm not sure. My CC definitely did. But, I'm not sure about this coach, yet.

[phorner]

My fan kicks in at 198 degrees.... as measured by an infrared thermometer at the top of the radiator inside the engine bay.

Drove home today about 3 hours in low - mid 90's and paid close attention to the coolant temps. The temperature would hold at 198 -199 and then drop down to 193 after the fan kicked in and basically just cycled in the area of 193 to 199.

[Ray Davis]

That's kind of the temps I was expecting. I'm not seeing the cycling as you described. In fact, temps would rise when driving slow, indicating to me there may be a problem. I'm gonna have to check this out before any more trips.

[Jon Wehrenberg]

Mine will run anywhere from 195 to about 210 depending on OAT and if I am running on level ground or pulling the hills, or descending a hill. That is based solely on my interpretation of a little round gauge whose accuracy I have never questioned or checked.

[JIM CHALOUPKA]

Finally got the old clutch unit out PITA. Very heavy aro 40# and must be lifted by outstreached arms with the casting passing through a space in two places simultaneously that only have .030 in clearance.

More to follow.

JIM

[JIM CHALOUPKA]

Prevost calls out AX74 to be the correct belt to go from the engine to the fan gear box.

My bus has AX73. Does anyone else use AX73 and why.

I have had no ill effects with the AX73 and am reluctant to change, but I also would like my bus to be up to Prevost specifications.

Opinions and discussion please!

JIM

[lonesome george]

Jim,
Mine has AX74 belts. I don't think the shorter belt can hurt anything, it is only about a 1/2" difference in center distance. I have had the entire pivot plate for the right angle gearbox and fan clutch out of our coach, where the bottom half of the pivot mounts to the chassis there are some large slots for adjustment of the whole thing. If you want to use the AX74 belt you may need to make an adjustment at that slot. What I made sure of is that the when the mount moves thru it's range of travel with the belts off the fan did not hit the shroud when the air bag was compressed and it did not hit the radiator before the mount stacked up on the hard stop on the air bag mounting bracket.

[phorner]

Jim, while your're in the radiator area, you may want to check the condition of the radiator core.

While at parliament coach recently having my OTR serviced, I also wanted to thoroughly go over the engine cooling system. I wasn't having any high temp issues, but since we're headed out to Arizona and Nevada at the end of July, I wanted to be pro-active.

So, we drained the coolant and pulled off the lower radiator hose to take a peek at the core. Not bad, but there was a build up of deposits that looked nasty, although none of the passages appeared plugged. I'll bet this hasn't ever been inspected on my coach.

After a thorough cleaning and several flush cycles, the difference was quite obvious.

Fresh coolant and a new coolant filter followed the cleaning. I do believe this process has dropped the running temperature a few degrees, as we never exceeded 199 on a 3 hour trip in 90 degree ambient air temperature. And, the temperature would drop down to about 193 after the fan kicked in.

Not the cleanest job to undertake as it's a challenge to capture all the coolant as well as the cleaning treatment gunk.

But I like the feeling of knowing that I've done about all I reasonably can to assure a trip without an overheating episode.

[JIM CHALOUPKA]

Good suggestion Paul. I will wait with that for now. Putting it off until I change the EC 1 coolant. I think that's the right designation.

A note on the fan clutch. I am confident in stating that my clutch has been changed before at least one time, so anyone with 115,000 ish miles would do well to keep an eye on things.

JIM

[Pete]

Jim, mine has the AX73's. When I had my fan clutch/radiator problem, prevost tried to put the AX74's on and could not get the clutch/a/c platform adjusted far enough away from the radiator to avoid possible contact. Thus the AX74's were installed.

[dreamchasers]

Jim, mine has the AX73's. When I had my fan clutch/radiator problem, prevost tried to put the AX74's on and could not get the clutch/a/c platform adjusted far enough away from the radiator to avoid possible contact. Thus the AX74's were installed.

Pete,

I have heard you mention concerning losing the three belts that drive the gearbox and the result was your radiator fan extended damaging your radiator. Sounds painful.

I checked my bracket and a piece of the metal bracket holding the small air bag that controls the belt tension will prevent this over extension of the fan. If you unit does not have this bracket design, perhaps an upgraded bracket would prevent future mishaps.

Hector

[Pete]

I'm sorry, thus the AX73's were installed. Sorry bout that

[Pete]

Hector, mine does have the bracket, and we modified that with a piece of rubber hose over the ear of the bracket to keep it from moving to far toward the radiator.
The next time we see each other, I can show you what we did. My radiator has an "X" brace from the upper left corner to the bottom right corner and the upper right corner to the bottom left corner. This "X" brace is about 1/4" in diameter and on the inside of the radiator nearest the fan. The damage was done when the assembly hit the "X" brace shearing off the fins on the round aluminum portion causing them to penetrate the radiator. Guess I am not very good at explaining things, hope this will be clear enough to understand.

[ajducote]

Started getting a "Growling" noise from my fan whenever the clutch kicked in on the fan. So I pulled the fan today and I have a small problem.
I need to remove the clutch to be able to get the fan blades off of the fan clutch assembly. I think I am suppose to remove the 3 small nuts in the center, but they are very rusty and frozen. Before I attack this with large dangerous tools, does anyone know for sure if these three nuts are the correct one's to remove? I will post pictures in the next thread on how I removed the fan.

[MangoMike]

Andre,

I removed mine on the Mothership three summers ago. Unfortunately I've completely forgotten the procedure. I do however have some pixs that I'll provide here. Hopefully they will be somewhat useful. What I do remember was that fan assembly was heavier than crap to get out of it's cradle.
5162

5163

5164

5165

5166

[MangoMike]

5167

5168

5169

5170

5171

[ajducote]

Mango,

Thanks, your last picture answers my question. I am going to order a new assembly tomorrow morning. As soon as I am sure 1 is on the way I will tackle the 3 bolts holding it together.

[hhoppe]

Once again Mango Magic saved the day. Great pictures Mike.

[ajducote]

Mango,

In the last 2 pictures above in your last post.

The new top half of the clutch is different then the old one. Did you drill out all the bolt holes and move the ring that contacts the magnets from the old clutch to the new top hat?



Thanks

[JIM CHALOUPKA]

Andre, these are the new parts I received and they were used as they were furnished by Prevost, nothing added or modified.



JIM

[ajducote]

A big thank you needs to go out to Jim and Mango. Both of these fine gentlemen called me and were able to help me get this done. The problem is that the new part number has a different electric cable connection on the fan end, and the heat sink on the clutch end (the finned part) is made a little different then the old part. I got it mostly back together today, but a real bad thunder storm hit, and I had to stop. I hope to finish tommorow and then I will post pictures of how it went all back together.

[ajducote]

This is what I did to put things back together.

5196
As received from Prevost
Original part number 550634
New part number as delivered 550837, cost $1175.49

5197
Remove the 3 center nuts, and remove heat sink

5198
Remove 3 bolts and remove ring

5199
Placed on Pulley, not bolted to pulley, use as a work stand

5200
Fan Installed

Continued in next post

[ajducote]

5201
Install magnetic ring with 3 bolts

5202
the piece on the bottom is the old part
the top piece is the new part

5203
Put heat sink on with 3 nuts

5204
Ready to go into Bus

5205
I removed the pipe from the charge air cooler and pushed it up as far as I could. This gave me room to slide the assembly into place.
Then I put the mounting plate onto the assembly. This is where taking pictures ahead of time paid off. Made it a lot easier to get things back in the same place.
The hole that is in the back angled part of the mount is where I used a large cable tie to fasten the wire from the clutch assembly. The change in design of the clutch prevents running it in the sane way that the original wire was run.

[ajducote]

5206
Pulley attached

5207
cable tie for holding wire

5208
fan running, no weird growling noice
SUCCESS !!

I used blue Loctite on all bolts and nuts

I suspect that the first indication that something was going bad with this part was a few months back when I started throwing the 3 belts that go to the gear box from the engine. Whenever the fan kicked in the whole fan mount would jump around. I raised the air pressure going to the air bags and that helped, but the whole fan assembly seem to still jerk to much when the fan kicked in.
Then I started hearing the growling noise.
Now with the new part, when the fan kicks in, it is MUCH smoother, and does not jerk when the fan kicks in.

[phorner]

Andre,

Great post! The pictures really do a terrific job of detailing this project. I'm sure it was much more of a job than your post makes it look.

Thanks for sharing!

[tdelorme]

Damn fine work Andre. I hate to think what Prevost would have charged you to do the rework/repair but north of three grand would not surprise me. Your documentation needs to go on the "articles" page. Well done.

[gmcbuffalo]

Andre can you put this post and your tow hitch post in the article section of this site? They are worth having there.
GregM

[ajducote]

It is a hard, dirty job. The clutch assembly is very heavy and the only things to grab onto for hand holds all move. I removed it on a Sunday, ordered the part Monday morning and it was delivered Tuesday at noon. I got it mostly installed on Tuesday, then a bad storm hit and I had to quit. Wednesday afternoon I finished up in about 1 hour. I am sure there is more then 1 way to do this, and probably a much better method. But when I tackle a job like this with no first hand knowledge, I just make it up as I go along. Hopefully the next person to do this will benefit from my pain and have a little easier job of it. But it does feel real good to get it done and not have to pay Prevost to do it. I will try to post all of this as an article this weekend. Thanks to all for the kind words and encourgement.

[Jon Wehrenberg]

Andre,

That is not only a great summary of the job accompanied by photos, but it should serve as inspiration to anyone that wants to tackle some of their own repairs.

Except for the fact our coaches are big, and some of the repairs involve heavy stuff we shade tree mechanics can do a lot of our own work. You have been added to the list of "experts". I think every one of us who has tackled a repair job ends up with a huge sense of satisfaction. I also feel that because we are not "professionals" we tend to go a little slower, exercise a little more care, treat the coach with greater respect, and in the end do a job as well as or better than most service facilities.

Great job.

[sawdust_128]

Impressive!!

[Jim Skiff]

A link to Andre's good work can be found here. He has contributed in the articles section.

Link to Article (http://www.prevostownersgroup.com/public/index.cfm?fuseaction=articles.view&id=7673&publicationtype=Articles)

Thanks Andre! :D

[Ron Meldrum]

You can view the page at http://forum.prevostownersgroup.com/content.php?20-Series-60-Fan-Clutch-by-Andre-Ducote

[hobobimmer]

Howdy all from East TN.

Joe Cannarozzi came to visit this weekend and do work on bus. One thing he identified (when checking all belts) was loud fan and fan hub, which didn't roll smoothly. He said Jim Chaloupka and (I think) Ed Mrozek had similar issue. What was your experience with this item? Did you have to order new and install? Any options besides the relatively pricey Prevost route?

Any help anyone on the site (in addition to Jim and Ed) can provide, I would appreciate. Thanks.

Eric Faires
Huntsville, TN
2003 Liberty

[garyde]

Hi Eric. I think I read a post last year about changing out the fan hub. I thought it was a relatively simple replacement.

[JIM CHALOUPKA]

Yes I changed mine out this time last year, so did Andre. Kevin E, Lonesome George and also Pete. I imagine there are others as well.

Just order up the part from Prevost about $1,100.00 and let Joe change it out.

My take is check it regularly by turning the fan itself and the fan drive pulley(two separate things to check for smoothness of operation) without the belt in place.

If you feel you must wash your engine keep the water away from the fan clutch.

The Prevost manual states do not power wash or steam clean the fan blade, use diesel fuel and a soft brush only.

I think there are three threads maybe two and an article by Andre.


JIM:)

[sawdust_128]

Not me. Andre did this and I believe he did an article on the process.

[truk4u]

Jimmy C - This is the second day in a row that I asked you to post a link for the old threads instead of starting new multiple threads of the same subject. It takes time to merge all these similar threads and I'm sure not everyone wants to scroll through 60 old threads just to look at the latest post.

Are you testing me for a "delete" function?