Author Topic: 1989 marquis side radiator fan  (Read 1480 times)

Sigbert All III

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1989 marquis side radiator fan
« on: November 29, 2022, 10:46:44 AM »
Good morning , I have a 1989 marquis with 6v92 Detroit with side radiator and trying to find out if fan is supposed to run all time or is there a solenoid or something that activates fan at certain temperature had drive replaced now fan not moving and running hot. Also if anyone knows someone interested in older beaver I will b selling mine as soon as I can get home . Sigbert All
1989 Marquis
C12 425hp

Steve Huber Co-Admin

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Re: 1989 marquis side radiator fan
« Reply #1 on: November 29, 2022, 02:50:12 PM »
Sigbert,
 What "drive" did you have replaced? 
The 1984-1994 Service Manual schematics show a booster fan that is electrically controlled, but I don't think this is the engine cooling fan. Diagram is on page E-0028. Access Coach Assist, then Beaver Motorhome History, then Schematics. The Service Data section shows a diagram for the engine compartment cooling fans, again electrically driven, but not the engine cooling fan.
Based on the above, I'd guess your engine fan is hydraulically driven and controlled by a wax valve.
Steve
Steve
2015-          07 Contessa Bayshore C9,  400 hp
2013-2015: 00 Marquis Tourmaline, C12, 425 hp
2005-2013: 01 Contessa Naples, 3126B, 330 hp

Sigbert All III

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Re: 1989 marquis side radiator fan
« Reply #2 on: November 29, 2022, 03:19:40 PM »
Thanks for reply yes it is hydrolic I replaced pump that drive power steering and radiator fan and it in turn blew out old seal on fan drive and replace with new drive but fan doesn't seem to be turning dumped twenty thousand on it since July and still haven't got it home
1989 Marquis
C12 425hp

Steve Huber Co-Admin

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Re: 1989 marquis side radiator fan
« Reply #3 on: November 29, 2022, 09:37:02 PM »
Sigbert,
The wax valve, if working, will cause the fan to turn relatively slowly when the engine is cool and increases speed as the engine warms up, but since yours is overheating, I'd think the shop that replaced the pump didn't hook something up correctly. If possible, I'd have them figure it out (assuming it was cooling correctly before the pump went bad).
Steve
Steve
2015-          07 Contessa Bayshore C9,  400 hp
2013-2015: 00 Marquis Tourmaline, C12, 425 hp
2005-2013: 01 Contessa Naples, 3126B, 330 hp

Eric Maclean

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Re: 1989 marquis side radiator fan
« Reply #4 on: November 30, 2022, 12:20:00 AM »
Sigbert
As Steve pointed out the fan should be turning all the time the engine is running .
There should be a switching valve connected to the fan motor it will have two smaller hydraulic lines and the larger hydraulic lines connected the two smaller line run to the wax pelet control valve Steve spoke of this should be mounted in the upper radiator hose .
The switching valve allows hydraulic pressure to bypass the fan motor and return to the tank, when the coolant temperature increases in the upper rad hose the wax valve allows hydraulic pressure to move to the switching valve which in return shutles the switching valve and stops the bypass causing the flow to go through the fan motor resulting in higher fan motor speed and cooling ability.
If yours is not turning the motor at all the switching valve must be bypassing all the oil ( not likely) or more likely the valve hoses are connected wrong .

Hope this helps
Eric
1997 Patriot Yorktown
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2009 Chevy HHR
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Eric Maclean

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Re: 1989 marquis side radiator fan
« Reply #5 on: November 30, 2022, 12:39:30 AM »
Sigbert
I have set you an email with a PDF attached with a description and troubleshooting artile for a blue bird bus which is very much the same as your system.

Hope this helps
Eric
1997 Patriot Yorktown
3126-B
2009 Chevy HHR
Roadmaster falcon tow bar
Demco Air Force one tow brake.

Sigbert All III

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Re: 1989 marquis side radiator fan
« Reply #6 on: November 30, 2022, 11:48:26 AM »
Thanks for your assistance I'm going to send file to shop working on my motorhome. He is talking about making fan where run open all the time will this hurt anything
1989 Marquis
C12 425hp

Fred Brooks

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Re: 1989 marquis side radiator fan
« Reply #7 on: November 30, 2022, 02:54:30 PM »
   Back when I worked at Vogue motorhomes in 1988, There was a device mounted on the 6V92 called the alarmstat. This device told the fan to come on at 186 degrees. The wires went to a solenoid valve that would open the hydralic flow to the fan motor. It was located near the upper center of the engine when you opened the rear engine access door. It was engineered to make the fan run continually in the event the alarmstat failed. Fred
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Steve Huber Co-Admin

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Re: 1989 marquis side radiator fan
« Reply #8 on: November 30, 2022, 04:51:54 PM »
If Fred's or Eric's ideas don't work, having the fan always running at full speed will slightly delay the engine getting to operating temp and may impact fuel mileage slightly. If you are running it in cold (winter temps) weather the heat up delay may be noticeable. Mine runs at full speed all the time and has not caused any issues.
Steve
Steve
2015-          07 Contessa Bayshore C9,  400 hp
2013-2015: 00 Marquis Tourmaline, C12, 425 hp
2005-2013: 01 Contessa Naples, 3126B, 330 hp