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Running Hot
Ok today’s issue was the coach was running hot and would not cool down unless I slowed down below 25MPH. After looking up previous post on cooling issues. I came to the conclusion my Fan clutch was not engaging. I called Prevost Pass and the tech gave me the Ohm readings the clutch should have 16 Ohm’s on one side and 46 Ohm’s on the other. Mine had 67 on one and 56 on the other so new clutch it is.
I did look at Jon’s post on how to lock the fan up and mine was a little different. But it got me in the right direction and after locking it up it stayed cool. Anyone know of a service center near Spanaway WA that is where I am now. Also here are the pictures of the clutch on my 07 Vantare with 05 Chassis.
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9 Replies
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There is a good shop in Ellenesberg Wa it’s a Detriot Volvo shop and they have one in Yakama, or drive to Vancouver Canada to the Prevost shop it’s not that far either
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For those unaware there are two ways to lock up a clutch on coaches equipped with the two speed electric clutches.
There have been discussions on this forum about both and just to tease you if you are not aware you have to do a search. As a clue, one involves removing relays, breaking off a tab and replacing the relay(s) and the other involves bolting locking tabs on the clutch itself.
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Bob, Glad you found the proper info…I knew it was there…you’re in an area where it should’nt be too hard to find service. Geo.
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infinity coach 253-891-0879 they are in sumner washington about 10m from you.. they do pretty good work…. Jim is the owner … they have done work on mine no problems,,,, parking lot pretty tight .. tell them your situation . his dad has or had a prevost and has been in your situation ….
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whats your phone number …. we can get you all plugged in and help or change the fan for you > just need to know how we can help and what your plans are …. call my cell 540-226-5229 i am about 5 miles from you
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My back hurts just thinking about changing the fan clutch. I replaced mine on my 97 coach and it was painful trying to lift that heavy thing into and out of place with my arms extrended.. I would rather eat bees than change another clutch without having the radiator removed,
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Sounds Like you found the problem but for future reference on this thread, this is the information Jon was referring too.
This info was from Prevost on this thread.
The advise you gave is correct and the method to lock the fan mechanically is correct.
We sometimes go to the rear junction box and find the two relays for the electrical functioning of the fan clutch. You have relay R78 for low speed and R79 for high speed. If you pull the relay and look at the spades coming out of the relay you will see that they are all marked (30, 87, 87a, 86, 85). Breakoff the 85 tab from the relay andre-install it in the coach. This will cause the fan to be locked electrically. It will stay in high speed now no matter what the engine ECM tells it to do. If the temperture now stays regular and in line with what you were seeing then there is a problem in the control of the fan clutch.
If this does nothing to regulate the temperature ( and you know for sure that the fan clutch is locked in). then you would have to look at the radiator, both externally and internally.
When you have the tab off the relay and you simply turn on the ignition switch(don’t start the engine!), go to the rear and grab the fan blade. It should not turn as it should be locked in electrically. If it still turns but with resistance then I would look to the fan clutch as the problem.
Either way, Jon’s method of mechanically locking the fan with the bolts would enable you to get to the servie facility safely.
One caveat! This mechanical lock up is for use to get you to a place of repair. If you try to use it in place of the controls you will find that the tab(s) will break off and then you would possibly not have a functioning fan clutch at all.If it just threatens to overheat , drive it to the service facility carefully watching the temperature. The normal safety shutdown on the engine for high coolant temperature will still shut off the engine to prevent damage.
There is more info on this thread.
Here is the setup for the two vehicle types. For the XL and XL2 we have R78 that controls the LOW speed or speed 1 and R79 that controls the HIGH speed or speed 2.
For the H3 series we have R84 for the LOW speed and R85 for the HIGH speed.
So if you break the tab (85) off of R78 you will be in low speed all the time except when the coolant temperature rises enough to get the high speed to come on. So turning on the ignition and not starting the vehicle you would find that the fan blade can be turned with just a little resistance. If you used R79 then the fan is locked on high and it moves with engine rpm all the time. It would be then locked when you did the ignition on/no start test you mentioned.
Ideally you should see if the fan will go into low speed normally but not high speed. Then you could use the modified relay in the high speed position to get better cooling all the time.
Keeping the fan locked in electrically this way is not good for long periods as this was a means to get you back home or to your destination and have the problem fixed.
On the extreme end of this issue would be that the fan has failed electrically. Then you need to use the bolts supplied on the fan clutch and you bolt the fan into fixed mechanical drive. This also is a temporary fix as you can eventually break off the tabs and then you have a free-wheeling fan with no control at all.
Davy
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Does anybody have the part number for the Fan Clutch on a 2005 and newer Series 60.
Bob
1999 XLV X-6872, liberty #440 -
If it is like the assembly I just installed, it was about $1300 delivered. It took me longer than it should have to change out but I spent 12 hours with an engine lift helping. I had to remove the pulleys, pipes, etc. The part number is available from Prevost.
Any mechanic familiar with these engines can exchange.
Pres
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