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Author Topic: Cooling fan always running  (Read 484 times)

Frank Bergamo

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Cooling fan always running
« on: April 09, 2019, 11:42:24 PM »
Cooling fan on my 2007 Marquis will not run at slow speed or no speed. Have bypassed thermo/wax valve with ball valve in bypass and still will not shut fan down. If I close ball valve, fan roars. My AC condenser is mounted  up front, so cooling fan does not need to run at start up or for low coolant temps. I have looked for restricters in line from switch valve on fan motor to thermal valve but have none. Do not have electronic controller, just thermo/wax valve in system. With fan running all the time, fuel mileage is very poor and coach is very sluggish. I have read that it can take 60-80 HP to turn fan at full wide open. Coolant temps are running 170F range. Allison temps at 150F-160F range. Not hot enough IMO. Anybody have any experience with this problem? Thanks, Frank.
« Last Edit: April 10, 2019, 01:33:30 AM by Frank Bergamo »
Frank & Paulette Bergamo
2019-       : 2007 Marquis Topaz IV  C-15 600 HP Allison 4000
2014-2019: 2002 Marquis Emerald C-12 505 HP Allison 4000
2004-2014: 1986 Executive Diplomat 3208 250 HP Allison MT-643
Grand Junction, CO.

Lee Welbanks

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Re: Cooling fan always running
« Reply #1 on: April 10, 2019, 04:59:21 AM »
On my 06 PT my fan runs on low speed until the Cat temp hits around 195 and you can hear it kick into high speed. Have you tried replacing the wax valve, I'm not sure but I think if the valve fails shut the fan will run at high spd all the time. With my C 13 I feel no difference at all when the fan jumps into high speed, I've watched the computer when in a hard pull 99% loaded and 49 psi boost and when the fan jumps to high speed there is no dip in RPM's, you cannot tell the difference.
A C 15 at 600 hp you should not be able to tell the difference either. Have you had your ECM flashed with any updates by Cat? Take it to Cat and have them hook up to it and see what you really have. Yours may have been messed with somewhere in the past and de-tuned.
My C 13 has plenty of get up and go, from a dead shop it will get up and move really quick if you want too, of course the fuel gauge has a opposite reaction.
Lee, Judy  & Pepper
06 Beaver Patriot Thunder
Wilmington IV 40
525 Cat, 4K Allison
2013 Honda CRV

Mike Shumack

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Re: Cooling fan always running
« Reply #2 on: April 10, 2019, 11:27:48 AM »
As stated, if you block the flow of oil at the Wax valve (Thermovalve) the fan should run at full speed. When the engine is cold (full flow through Wax valve, the fan should slow or stop). Since you have bypassed the Wax valve (I assume you connected the two hyd hoses together) and the fan did not stop, I would suspect the Switching Valve (on the Hyd motor) is stuck or faulty.

There was a thread on another forum (PM me if you want a link to it) where the OP said the hoses to the Wax Valve were reversed and that caused his fan to run full speed all the time. Although I'm not sure why it would matter as the valve appears to just be a straight "flow through" with volume depending on how far the valve is opened. The Inlet is the hose at the end of the valve furthest from the radiator. But the diagram does specifically identify the Inlet and Outlet, so it must matter.
« Last Edit: April 10, 2019, 12:56:54 PM by Mike Shumack »
- Mike

'05 Beaver Patriot Thunder, Vicksburg, CAT C13  525HP, Allison 4000MH, HydraLift

Dave Atherton

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Re: Cooling fan always running
« Reply #3 on: April 10, 2019, 01:31:29 PM »
Gentleman, my suggestion be very careful going around system to correct a unknown problem.
The engine fan power is connect into the ECM and the speed high and low. Can tell you which pins are involved if need but at present. Changing or going around a value that is connected into your
engine ECM may come with risk or shorting out positive or ground pin within ECM.
Dave Atherton Retired Cat Mechanic

Mike Shumack

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Re: Cooling fan always running
« Reply #4 on: April 10, 2019, 02:09:40 PM »
It sounds like Frank's 2007 system was changed from the Sauer Danfoss FDCA (electronic fan control) to the (mechanical) Wax valve setup, like in my older 2005 Patriot.  The older Wax Valve setup is not tied to the engine ECM.

I have read on the forums that some coach owners are swapping over to the older Wax Valve setup when their FDCA fails because it is less expensive than replacing the FDCA controller.

Dave's comment has me wondering - do those coaches with the "electronic FDCA controller" provide any feedback to the engine ECM (the FDCA Specs say there is a 3-pin connector for data communications between "FDC and a personal computer via CAN". There is no mention of data being provided to engine ECM though.


- Mike

'05 Beaver Patriot Thunder, Vicksburg, CAT C13  525HP, Allison 4000MH, HydraLift

Frank Bergamo

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Re: Cooling fan always running
« Reply #5 on: April 10, 2019, 02:39:00 PM »
Gentlemen, I have not been able to locate any electronic control modules in my system. As Mike stated, my system is a mechanical loop that runs from hydraulic pump on motor, to fan motor, and then into switching valve mounted on fan motor. Out of switch valve it then runs to wax valve, then back to fan motor, then returns to tank reservoir. I am also thinking that switch valve may not be operating properly. Another thought is that the #4 lines from switch valve to wax valve and then back are not big enough to relieve pressure to slow down fan. Am thinking about replacing lines with #6 line to get more flow away from switching valve. Regarding switch valve, I have not been able to locate any info. All I can find is the complete fan motor assembly with switch valve installed. I would think that the switch valve would have a rebuild kit, but so far have been unable to locate one. My Saur Danfoss fan motor # 551-1-01303-210 is available, but would be nice to locate a rebuild kit, as complete fan motor assembly is $1,400.00. Again, thanks for any help, Frank.
Frank & Paulette Bergamo
2019-       : 2007 Marquis Topaz IV  C-15 600 HP Allison 4000
2014-2019: 2002 Marquis Emerald C-12 505 HP Allison 4000
2004-2014: 1986 Executive Diplomat 3208 250 HP Allison MT-643
Grand Junction, CO.

Mike Shumack

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Re: Cooling fan always running
« Reply #6 on: April 10, 2019, 03:57:39 PM »
That is the same pump in my 2005.
The -4 hoses should be fine. I'll confirm the size used on my coach when I get home - but -4 (1/4") sounds right.

This may be a good source to locate the parts you need. https://hydraulic.net/
From what I have read the old part number is no good (not available), and you will need to change to a new pump (or maybe can just get a Switching Valve) - but the guys at the website above have done this before for other Monaco owners and get get you parts you need.

If you go that route post back the new pump make/model/pn's so we will know what to get when our turn comes.
Good luck
« Last Edit: April 10, 2019, 04:14:49 PM by Mike Shumack »
- Mike

'05 Beaver Patriot Thunder, Vicksburg, CAT C13  525HP, Allison 4000MH, HydraLift

Frank Bergamo

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Re: Cooling fan always running
« Reply #7 on: April 11, 2019, 03:27:14 AM »
Update: Cooling fan always running. Replaced hydraulic lines today with #6 lines. Still not bypassing enough fluid to shut down/slow down fan motor. Had coach out in 46 degree weather and fan still rotating way to fast. Will call hydraulic shop Mike posted tomorrow and see what they can come up with. Still no luck on switch valve info, will post any info when issue is resolved. Thanks for everyone's help!! Frank.
Frank & Paulette Bergamo
2019-       : 2007 Marquis Topaz IV  C-15 600 HP Allison 4000
2014-2019: 2002 Marquis Emerald C-12 505 HP Allison 4000
2004-2014: 1986 Executive Diplomat 3208 250 HP Allison MT-643
Grand Junction, CO.

Mike Shumack

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  • Orlando, Florida
Re: Cooling fan always running
« Reply #8 on: April 12, 2019, 11:14:38 AM »
BTW - I was on the NW RV Supply website and noticed they list quite a few hydraulic fan motors. I didn't look specifically for yours - but the few I looked at were in stock. so maybe check here to http://www.nwrvsupply.com/category/05-05.html.  They also list a rebuild-seal Kit on the site.
- Mike

'05 Beaver Patriot Thunder, Vicksburg, CAT C13  525HP, Allison 4000MH, HydraLift