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Old 09-10-2014, 11:52 AM   #1
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Location: Traveling in North America
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Fan Motor Leak

We're in Kingman, AZ with a hydraulic leak that seems to be from the fan pump motor (I'm not sure if that is correct). We're at a Great West Truck and they want to tear it apart to find the part numbers. The coach didn't overheat, but was getting warm so we were going slow on the last couple of climbs to get here and when setting up Dave noticed a lot of fluid below the radiator area. It is hydraulic fluid.

We're fulltimers, so we are sort of in a pickle in that if they tear it apart and can't put it back we're out of a home for an indeterminate amount of time. We don't mind waiting for parts (there is an RV park nearby that we could stay in) but we don't want to be out of the coach and in a hotel for a huge number of weeks. So any ideas/part numbers would be so helpful because right now I'm terrified of what is happening.


Barbara & David O'Keeffe
Figment II (Alpine 2002 36 MDDS)
On The Road since 2006
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Old 09-10-2014, 02:03 PM   #2
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I had to replace the fan motor on my coach last year because it was leaking from the seal. Got it here:
You can look up the hydraulic motors and see if yours is there. They were able to tell me which one I needed by the coach VIN.
Naturally, the one I needed was the most expensive one........

2005 Newmar Dutch Star 4024
Pulling my 2012 Malibu w/Blue OX & Patriot brake unit
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Old 09-10-2014, 05:16 PM   #3
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Smile Fan leak

We had a similar leak several years ago. DH cleaned the area and was able to see that it was either the in take hose or the outlet hose so we took in to the shop and all they needed to do was tighten it up for $150. It has not leaked for two years now. Hopefully your problem will be as simple as this.
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Old 09-10-2014, 05:19 PM   #4
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Just a note, going slow does not help unless you do it in a lower gear. Keep the RPM's up to keep the air flowing across the radiator (once you get the fan fixed)! Optimum cooling is in the range of 1,500 - 2,000.
Dave, Bobbi and Fenway
2005 38' FDTS Alpine Limited, 2016 Jeep Grand Cherokee Limited
Cape Cod, MA
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Old 09-10-2014, 05:39 PM   #5
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We found this in an earlier post about "Thermostatic valve" It shows a fan motor from Sauer-Sundstrand part# B5511-1143-170. Hope this helps!

"09-11-2010, 04:03 PM #22
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Location: Auburn, CA, Havasu, AZ & Mulege, BCS
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Sauer's docs say the wax valve goes from min to max over "12-15F. This eliminates sudden changes in speed that would cause dramatic changes in noise levels and place high transient stress on drive components. Without modulation, as the fan 'cut in' occurs withe engine at maximum speed, the fan would accelerate almost instantly from rest to perhaps 3000 RPM. Such high acceleration requires proportionally high driving torque and makes the achievement of reliable long term operation more difficult." so the mfgr shows a 3 variation. My guess regarding some vs. no RPMs on cold start is that the variation implies the end points are not hard stops, or else the wax varies over time as it wears from repeated expansion/cooling.

I'll be posting the fan motor technical info to the Tech Library shortly. I also received recently a Chassis Data Card from an 01 model 34 feeter. It shows a fan motor from Sauer-Sundstrand part# B5511-1143-170 and a fan motor thermovalve part# B5531-09857-190 (which matches the above post w/wax valve part#). That's the 199 cut-in unit previously discussed. While I'm naming names, the Sauer-Sundstrand hydraulic pump (shaft-driven off the forward end of the engine's air compressor) is part# B5501-35765-160-160. Since it appears the wax valve model has changed little over the years, the fan motor & pump numbers should also be recognizable to hydraulics vendors worth dealing with if need arises.
Baja-tested '08 2-slide 36'
Alpine: The Ultimate DIY'er Project"
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Old 09-11-2014, 10:01 AM   #6
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The Sauer-Sundstrand motor is no longer made. If the motor itself is leaking, your best bet is to get it rebuilt with new seals. Here is a thread on the subject: Leaking Hydraulic Fan Motor
1999 Alpine Coach
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Old 09-11-2014, 10:22 AM   #7
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Although I cannot help you with your leak I can give you a suggestion from a full-timers point of view. Do Not have your rig repaired at a place that will not let you stay in the rig if the repairs take longer than a day. Most places that work on trucks and RVs will let you stay with the rig during the repair process so you do not have to stay in a motel.

Ken Tarkin
2005 34' Alpine
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Old 09-12-2014, 06:39 PM   #8
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Sauer no longer makes the pump, not sure about the motor for fan. But Sauer sold the pump line to another company and units are available.

Determine if a fitting can be tightened & if not, Take the part#'s & call your local Berensen Fluid Power location (google), they can match the old part# too the current one & order parts.

Baja-tested '08 2-slide 36'
Alpine: The Ultimate DIY'er Project
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fan, leak

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