Hydralic Fan System Pressure Gauge Location

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Hydralic Fan System Pressure Gauge Location

June 01, 2014, 07:56:59 pm

My 95 U240 hydraulic fans are running slow.
full throttle rpm(2750) low speed fan rpm 1500 should be 1900
full throttle rpm(2750) high speed fan rpm 2200 should be 2930

I have attached a drawing of my fan system. There seams to be two(2) outputs from the pump. I want to check the output pressure of the pump. At full throttle the pump should output 1600PSI. I need to know where to connect a pressure gauge. The most accessable location is either at the High/Low switch(position A) or at the Sun Controller(position B). Either of these locations can be see easily, but which is the correct location.

Pat,

Re: Hydralic Fan System Pressure Gauge Location

Reply #1 – June 01, 2014, 09:33:04 pm

I use a Tee that goes between the pump and line out, then screw in the 4,000 psi gauge.
Not on the motor home. but on tractor, would think this would work on any hydraulic system.
Am told the HWH room slide requires 3,000 psi (been a while ago, I may have forgotten) to close the switch that activates the system. Problem was the pressure switch, the pressure was OK.
Love playing these games.

Re: Hydralic Fan System Pressure Gauge Location

Reply #2 – June 02, 2014, 07:32:17 am

Pat
Looking at your diagram without arrows showing the direction of flow seems confusing. Hydraulic is like electricity. It has to flow in one direction. You have a high pressure and flow side and a low pressure return to tank side. Your sun control is your relief or can be called safety for the high pressure. Your high low is a electric controled valve that deverts oil back to tank for low speed. The gauge should go on the outlet of the pump. Rpm of the fans is created by flow. Pressure is created from the resistance of the motor. You need to check flow also. You can have pressure but not flow.

Re: Hydralic Fan System Pressure Gauge Location

Reply #3 – June 02, 2014, 10:11:42 am

I agree with alan and dave, but I don't have the knowledge to know the direction of flow. I can see on the pump that there are two(2) hoses returning to tank. I assumed that the other two(2) hoses coming from the pump both are pressure hoses. Which one do I put the gauge on( at point A or point B) on the drawing? I don't know.
I have placed a switch in series with the ground side of the high/low control value. I can now choose high speed or low speed by turning on or off my switch. The high/low value is always on(12 volts applied to solenoid) selecting the low speed for the fans until the engine temperature reaches some predetermined temperature(maybe 220, again I don't know). I think that there must be some flow. The fans do run, just seams to be too slow(about 700 rpm).

Re: Hydralic Fan System Pressure Gauge Location

Reply #4 – June 02, 2014, 10:37:20 am

Pat,
Have you reviewed this already? Need help understanding my radiator hydraulics

Re: Hydralic Fan System Pressure Gauge Location

Reply #5 – June 02, 2014, 08:04:14 pm

I have followed the thread all the way. My problem seams to be a lot the same.

I did a test drive today from Lufkin,TX to Livingston,TX at 60-65MPH. The ambient temp was 88 deg. On the way down started out on low speed fan. Reached thermostat temp (181) about 8 miles down road(normal). Shortly later temp rises slowly to 201, switched to high speed fan. The temp cooled down to about 197-198. On arriving at Shrimp Boat Manny's I had a crawfish etouffe with fries. The food was worth the test drive. So on the way home, started with high fan speed, 60 MPH and never got over 190 all the way home. I am thinking the pump is just weak/worn?? or can I get higher fan speeds by changing the Sun Controller?? Does it hurt to run on high fan speed all the time??

Pat,

Re: Hydralic Fan System Pressure Gauge Location

Reply #6 – June 03, 2014, 01:50:50 am

Pat,

The Sun Controller allows quite a high range of PSI adjustments. When the hydraulic pump on our 1993 U240 had a catastrophic failure and the pump was not available Foretravel send me a new pump and fan motor and Sun controller. Had hoses per their schematics made locally and installed.

Started the engine and had ZERO RPM on the fan. Almost went into cardiac arrest for a minute, then wondered if the Sun Controller was properly adjusted (James Triana had provided PSI@ governed RPM specs for the system). Well, 1 3/4 turns of the Sun Controller adjustment screw (the allen head under the 9/16" cap) brought everything into spec with no more problems in the years to follow.

Your system is more complex (two fans and two speed), but James should be able to tell you where to hook the gauge and what PSI to set the Sun Controller.

I sure would not assume a pump was bad just because PSI is low until after adjusting the Sun Controller.

Brett

Re: Hydralic Fan System Pressure Gauge Location

Reply #7 – June 03, 2014, 11:03:16 am

Good Morning All,
I have just now made a test of adjusting the sun controller. With fans running on high and low speed, i have turned the sun controller allen head 2 turns both in and out with no change in fan speed. I tried this test at engine idle speed and at engine 1300 rpm. Fan speed rises with engine speed like you would think it should. Fan speed increases when high speed is selected manually. What does this all mean??

Pat,

Re: Hydralic Fan System Pressure Gauge Location

Reply #8 – June 03, 2014, 12:28:03 pm

Pat,

Might be a question for the folks at Sun. Would be better if you could give them PSI readings.

Total speculation-- wonder if the Sun Controller piston could be stuck in its bore and you are really not adjusting PSI?

I have not worked "inside" the Sun Controller-- hopefully, their techs will be of assistance.

Re: Hydralic Fan System Pressure Gauge Location

Reply #9 – June 03, 2014, 05:07:15 pm

I have adjusted the sun controller to both extremes. With the sun controller all the way in the fan are still running at the same low speed. With the sub controller all the way out, the fans slow to about 100rpm. I still cannot increase the fan speed. I am at a lost. My guess is still the pump.

Pat,

Re: Hydralic Fan System Pressure Gauge Location

Reply #10 – June 03, 2014, 10:18:32 pm

Pat,

Your symptoms sound almost exactly like mine. No matter how I adjusted the the Sun Hydraulics relief valve the pressure stayed the same.

Alan is exactly right. A flow gauge would tell you how much fluid is pushing the fans but since you don't have pressure & you have low fan speed I can pretty much tell you you don't have enough flow. To me that points to the pump. I think you've already figured that out yourself.

I've done a quick markup of your hydraulics diagram with my "opinion" on how it flows. Also where the pressure gauge should go. You want to know the pressure the fan sees which is best measured after the Sun Hydraulics relief valve. I inserted a tee directly on the outlet side of the Sun Hydraulics since it was easy to get to. It could also be placed on the other end of the hose where it tees to the two fans if it is more convenient.

Best of luck. Hydraulics are great when they work but a PIA when they don't!

see ya
ken

Re: Hydralic Fan System Pressure Gauge Location

Reply #11 – June 04, 2014, 06:37:06 am

OK here is the scoop all adjustments should be made at engine highway rpm. My m11 at 70 is around 1700. Flow IS direct relation to fan rpm and flow is direct relation to engine rpm. You are dealing with a Vickers gear pump. With the age of your unit I would also guess that it is all original. Pumps fail and motor (fan) fail. A decent gauge is 50 to 80 bucks for anolog. Your best investment if you are going to do this is to buy Both a flow meter and a gauge. They will tee in line out of the pump. The flow meter will tell you if the pump
Produces proper flow to turn the motors at correct rpm. You are also dealing with 2 motors in parrellel if 1 of the motors are failing this will cause your problem. Oil goes to the least resistance which would also explains your adjustments not changing much. A quick check is to take the case drain off of the motors one at a time and run and see if one bypasses more through the case drain then the other. Changing parts is very expensive. I believe in diagnosis.
Not sure of you pump set up but I would guess you have one big hose for tank supply a small hose on the side of the case for case drain and may be one or two out let's. Some coaches power steering is supplied by a second pump that looks like one. You really have to trace every hose or have a schematic. Pm me if you like. There are a lot of places to get all of these parts.
Good Luck
Oh yea yes you can leave it on high. It requires a little more HP to run it like this. Your fail safe is high speed. Meaning if the coil or electric circuit dies it stays on high.
Happy camping!!!!!!

Re: Hydralic Fan System Pressure Gauge Location

Reply #12 – June 04, 2014, 05:08:41 pm

Thanks for replies,
I know the high/low solenoid and value both work. I know that adjusting the sun controller does nothing to help. All that is left is the pump and fan motors. If I find out the pressure and flow of fluid in the system, I cannot replace the pump and I hope it is not the fan motors. So I guess I will wait until July 28 for FOT to look at it.

Pat,

Re: Hydralic Fan System Pressure Gauge Location

Reply #13 – June 12, 2014, 02:28:23 pm

I just got back from diesel diagnostics and having a pressure gauge installed in the hydraulic fan system. It is installed at the fan high/low speed control value. At full throttle(2750rpm) and fans on low speed the reading is 700psi, again at full throttle(2750rpm) and fans manually set to high speed the reading is 1300psi. Well I still don't know what the problem source is!! James T. at FOT said pump output at full throttle should be 1600psi. He did not say anything about high/low speed stuff.

Where is go from here?

Pat

Re: Hydralic Fan System Pressure Gauge Location

Reply #14 – June 12, 2014, 06:10:36 pm

Pat,

Still could be the Sun controller-- I suspect it because you said that adjusting it made zero difference in pressure. Wonder if piston is seized in the bore?

It could be the pump, but even a brand new pump at full PSI could have pressure bleed off if the controller is not working correctly.

Might have the hydraulic shop temporarily put a plug in the return line from the Sun Controller and see what kind of PSI you can generate.

Brett

Re: Hydralic Fan System Pressure Gauge Location

Reply #15 – June 15, 2014, 08:44:12 pm

OK I just got back and my m11 at 1600 rpm is exactly 75 mph. So what is highway rpm depends on engine type and transmission.

A hydraulic pump just free pumping does not produce pressure it produces flow. A good pump produces flow and pressure with a motor,cylinder or what ever. The resistance or force of the device that the pump is supplying produces the pressure. Say you have a motor with no fan blade will have very low pressure. Same motor with a fan blade attached will have more resistance which equates to more resistance and a higher pressure. A worn pump will not produce enough flow or pressure to run your motor. There is a thread very similar to this one that ended with the pump being worn or weak dead does nothing. To condem a motor I put a flow meter in line with the pump outlet a tee with a gauge then open the sun controller (relief (safety device)). Open backed off, cap the inlet to the fan start engine idle slowly turn relief in watch pressure rise. Sun controller should make a hissing noise as pressure rises that is oil bypassing through the relief back to tank. I set my relief to factory specs if you have it. Probably around 2000. If pump can't produce the pressure it is worn. If so next test is for flow. Reconnect line to motor start engine and run to highway rpm.with flow meter and pressure gauge inline, if flow meter show correct flow and your pressure does not exceed relief pressure that you set earlier and motor is not turn to correct rpm a photo tach works for this then the motor is dead. No tools or proper tools can make you spend a lot of money. Most shops can help.

Re: Hydralic Fan System Pressure Gauge Location

Reply #16 – July 28, 2014, 08:22:53 pm

Well I had my appt. with foretravel today to check/repair hydraulic fans running at slower speed. Replaced the hydraulic pump, replace sun controller cartridge. 8 hours of labor and I had to leave it at there. No change/improvement in fan speed, still at 2200rpm with full throttle, about 700rpm too slow.
Any Ideas???

Pat

Re: Hydralic Fan System Pressure Gauge Location

Reply #17 – July 28, 2014, 08:34:49 pm

Quote from: pthurman48 – July 28, 2014, 08:22:53 pm

Well I had my appt. with foretravel today to check/repair hydraulic fans running at slower speed. Replaced the hydraulic pump, replace sun controller cartridge. 8 hours of labor and I had to leave it at there. No change/improvement in fan speed, still at 2200rpm with full throttle, about 700rpm too slow.
Any Ideas???

Pat

Pump drive pulley incorrect size? Previously worked on stuff is always suspect. If the pump is good and the fan motors good and the controller is good my un educated thought was that the pump is spinning too slowly.

Re: Hydralic Fan System Pressure Gauge Location

Reply #18 – July 28, 2014, 08:40:41 pm

I don't know the gentleman's name, but one of the techs checked with eng. about that. Someone also said something about what others may have changed/done.

Thanks for the comments Caflashbob
Pat,

Re: Hydralic Fan System Pressure Gauge Location

Reply #19 – July 29, 2014, 10:24:38 am

@Pat I feel for you!

I'm not sure what you mean by

Quote

8 hours of labor and I had to leave it at there.

Did you exceed your budget? Did Foretravel run out of ideas?

So is the Sun Controller cranked all the way in and the pressure is still only 1300psi? If so I'd appeal Mark Harvey (shop manager). You've invested 8 hours labor with no improvement. FOT needs to work with you to get this right. They are the ones that designed it they HAVE to be able to get it back to specs! IMHO...

Good luck and keep us posted.

see ya
ken

Re: Hydralic Fan System Pressure Gauge Location

Reply #20 – July 29, 2014, 07:33:17 pm

Well I went back to FOT today at 1:00pm. Oh NO. It was still up on blocks. After speaking with Mark and Joshua, it is the fan motors. They changed the hydraulic pump, and the cartridge in the sun controller block along with 10+ hours labor. Tested and eliminated the high/low fan switch. The fan motors must be replaced in pairs. The original motors are no longer available, but with new motors, a FOT upgrade kit, and 9+ hours labor(they told me I should be able to do the work) to upgrade the fan system it can be repaired. I don't have money now, suppose to leave for Colorado on the 31st, so now I have new pump and sun controller and will have to replace the fan motors at a later date. It is a good day. Joshua, Mark, Clif, Arron, and Alton all worked real hard on the issue. Thank you FOT.

Pat,

Re: Hydralic Fan System Pressure Gauge Location

Reply #21 – July 29, 2014, 08:27:22 pm

I don't really know anything about this setup on your motorhomes but is it feasible to change everything over to electric fans rather than hydraulic.

I'm sure others have looked into it. Just curious.

Re: Hydralic Fan System Pressure Gauge Location

Reply #22 – July 29, 2014, 09:45:02 pm

@Pat Great news! Sort of I guess...

I've changed out my fan motor with a replacement kit from FOT and it went very smooth. Just unbolt everything and bolt in the new kit. It was expensive! About $1,200 for one fan. I hope yours are less.

If you have fan drains on your motors be sure to blow back through the drain hose to make sure they are clear. If you can't replace the hose(s). If the motor can't drain it will overpressure and blow the seal. Don't ask me how I know this.

Pro tip: Go to a hydraulic shop and get several sets of hydraulic caps and plugs (see attachment). Using these you don't need to drain all of the hydraulic oil which is a PITA! I just used a wrench on the hose I was going to remove to determine the size of the plug. Went to the hydraulic shop and told them the wrench size and the were able to match up the cap and plug. If they are unwilling to help go to another shop. As I've said before I've never found a more helpful group then ALL of the hydraulic shops I've been to and I've been to plenty!

Anyway once you have the cap and plugs just unscrew the hose with a container underneath to catch fluid and put the cap and plug in place. I rarely lost more then a 1/2 a cup of fluid using this method. Be sure to put a wrench on both ends of every hose you need to remove and keep a count of how many you need.

see ya
ken

Re: Hydralic Fan System Pressure Gauge Location

Reply #23 – July 30, 2014, 09:35:09 am

Quote from: pthurman48 – July 28, 2014, 08:22:53 pm

Well I had my appt. with foretravel today to check/repair hydraulic fans running at slower speed. Replaced the hydraulic pump, replace sun controller cartridge. 8 hours of labor and I had to leave it at there. No change/improvement in fan speed, still at 2200rpm with full throttle, about 700rpm too slow.
Any Ideas???

Pat

This is the kind of "troubleshooting" that really annoys me. Troubleshooting by blindly replacing parts at the owners expense. Just not right.

Roland

Re: Hydralic Fan System Pressure Gauge Location

Reply #24 – July 30, 2014, 09:37:09 am

Actually it doesn't "annoy" me it really pis... me off.

Roland

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