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-Gramps- · 12-15-2021, 05:52 AM

Quote:

Originally Posted by House Husband

Oshkosh chassis made a 460 gas pusher many years ago. It had heating problems because they left the engine fan as a puller instead of having it push air through the radiator. Water pump bearings are designed to handle some lateral thrust so the water pump bearings must be turned around when changing the airflow direction. WorkHorse blamed their water pump issues on the fan clutch when the real problem was the lateral thrust on the water pump bearings.

Richard

Actually, that is not what the problem was. The FCA had a temperature sensing problem. The assembly is full of oil which heats up to a certain point and then the fan motor turns on which drives the fan and the pump. Normally the fan is free-flowing. The manufacturer of the FCA used the wrong viscosity of oil in the assembly, too thin so to speak. The oil would heat up which caused the fan to run almost all the time until it ran itself apart. The recall replaced all the FCAs, including the water pumps with the proper unit. I never had an issue happen with mine but it was replaced. We owners discovered that the main symptom that a coach had a bad FCA was that the mileage was lower and you could hear it running all the time even at idle even without the rear camera mike on. Normally I never hear the engine FCA run unless I am in low gear climbing a mountain. The engine is so quiet I have to tell techs who are moving the coach not to start the engine twice.

edgray · 12-15-2021, 08:38 AM

Derrick: I don't disagree with what you say about the FCA oil issue, but IF that was the ONLY contributing factor that caused the TSB, why would WCC have replaced all the water pumps?
Also, I believe you are mistaken about the water pump being "driven" by the "fan motor". I think most all water pumps are driven by the fan belt, which is driven whenever the motor is running off of the crankshaft pulley, regardless of what the FCU is doing to the fan itself. IOW, the FCU isn't running the pump-just the fan.

-Gramps- · 12-15-2021, 09:01 AM

Quote:

Originally Posted by edgray

Derrick: I don't disagree with what you say about the FCA oil issue, but IF that was the ONLY contributing factor that caused the TSB, why would WCC have replaced all the water pumps?
Also, I believe you are mistaken about the water pump being "driven" by the "fan motor". I think most all water pumps are driven by the fan belt, which is driven whenever the motor is running off of the crankshaft pulley, regardless of what the FCU is doing to the fan itself. IOW, the FCU isn't running the pump-just the fan.

Workhorse decided that to be sure of replacing any damaged parts, including the water pump, from being over-torqued so to speak, they replaced the whole FCA and the pumps, it was not due to some poor water pump design. And yes the pump is driven by the fan belt, which means that when the FCA revved up the fan, the pump ran harder also. I think we both know that. Look I own one of these for 14 years now. I was involved with the marketing of this chassis and its history. I was good friends with the chief product engineer for the R-26 and he kept me very informed on everything about this chassis. Ed Gray and Milke Pelchat (driver ) also know a great deal about the UFO and they can probably explain things in greater tech detail I can.

House Husband · 12-16-2021, 10:51 AM

Quote:

Originally Posted by -Gramps-

Workhorse decided that to be sure of replacing any damaged parts, including the water pump, from being over-torqued so to speak, they replaced the whole FCA and the pumps, it was not due to some poor water pump design. And yes the pump is driven by the fan belt, which means that when the FCA revved up the fan, the pump ran harder also. I think we both know that. Look I own one of these for 14 years now. I was involved with the marketing of this chassis and its history. I was good friends with the chief product engineer for the R-26 and he kept me very informed on everything about this chassis. Ed Gray and Milke Pelchat (driver ) also know a great deal about the UFO and they can probably explain things in greater tech detail I can.

You make my point exactly.......The fan was pushing very hard on water pump bearings that were designed for a puller, not a pusher. When the load was reduced on the bearings, they tolerated the error.
Also the fan clutches are not filled with oil but are filled with silicone.
There are heavy duty fans out there with out clutches, that impose very high pressures on water pump bearings all the time, with out high failure rates.

Richard

-Gramps- · 12-16-2021, 01:33 PM

Well I being the owner of a UFO for 14 years has been put in my place by the superior knowledge of a 95 Bounder owner so I guess this thread has come to an end. For me at least.

UFO Pilot · 12-16-2021, 01:44 PM

Quote:

Originally Posted by -Gramps-

Well I being the owner of a UFO for 14 years has been put in my place by the superior knowledge of a 95 Bounder owner so I guess this thread has come to an end. For me at least.

People who have never owned one know more about them the those of us who have owned one for many years.

I usually stay out of these threads because of all the misinformation that is thrown about.

-Gramps- · 12-16-2021, 01:51 PM

Quote:

Originally Posted by UFO Pilot

People who have never owned one know more about them the those of us who have owned one for many years.

I usually stay out of these threads because of all the misinformation that is thrown about.

You are correct, just stay out of it. I should have remembered that. The posts n this thread remind me why I prefer the GAS pushers (UFO and Friends)
Facebook group. The information there is not only helpful but friendly. Thanks for the reply.

-Gramps- · 12-16-2021, 04:29 PM

I said I was done with this thread but as a UFO owner, I don't particularly care for being told I don't know my own coach. So I have this to say, I did not post what kind of oil is in a UFO FCA. So here it is. Most fan clutches including the UFO's are filled with silicone-based oil. The oil is held in an internal reservoir when the fan is disengaged. To engage the fan, thermostat-controlled internal valves open and allow the fluid to fill the working area of the clutch. This creates friction between the drive plate and the housing, causing the fan to spin.

The UFO FCA that had a problem had the wrong viscosity of oil, it heated up too much too soon, so the thermostat opened the valves, which caused the fan and the water pump to run too often and for too long at too much speed. This put a strain on the system and cut mileage. When the fan should have been free-wheeling turning by airflow at a lower rpm rate and the water pump also operating at a lower rpm the FCA continued to engage, it's that simple. It had nothing to do with bearings or push-pull direction because I know that Workhorse reversed engineered the whole cooling system to work "backward" for a gas pusher including using a larger than normal radiator pack which caused the engine to run too cool during its initial trials. These trials were done in Death Valley with the Monaco LaPalma prototype. The cooling system had to be adjusted to make the engine run more efficiently. It is a great chassis and yes it had some blips during its early years, with the FCA (the water pump was sometimes collateral damage) and with the Hydraulic brake control unit, but all these problems have been addressed and fixed. No spark plugs flying out the engine block, no DEF tank sensor breaking down and shutting down the engine, nothing like that. So it's the best gas chassis ever made, and I think it's a crying shame it is still not in production.

CamJam1 · 12-16-2021, 07:50 PM

Didn't anticipate that this topic might be controversial but appreciate the responses. We love our front-engine Dolphin, but I'd certainly look at the UFO if we were in the market for a new rig.

UFO Pilot · 12-16-2021, 07:56 PM

There is so much wrong info posted about the UFO Chassis that a few of us long time owners feel the need to correct the bad info.

House Husband · 12-17-2021, 09:48 AM

Quote:

Originally Posted by UFO Pilot

People who have never owned one know more about them the those of us who have owned one for many years.

I usually stay out of these threads because of all the misinformation that is thrown about.

And have you run a RV repair service like I did? Do you have the capacity to repair engines, transmissions and differentials? Just because I happen to drive SOB doesn't mean my knowledge is limited to one brand. I didn't share misinformation. I just shared the real truth about Workhorse's water pump failures. Most on here including you were unaware that water pump bearings support lateral thrust. Go prove me wrong..

Richard

**Lt Dan** · 12-22-2021, 10:52 AM

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