Big Radiator Fan "HUB"

[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.