Fan RPM

Topic: Fan RPM (Read 1052 times) previous topic - next topic

Fan RPM

March 23, 2022, 09:46:29 pm

Anyone know what the hydraulic fan speed on the two cooling fans should be at high speed? 2000' U320 with Cummins ISM450. Currently they are spinning opposite directions and maxing out at 250 RPM (I know they are both supposed to be spinning the same way and drawing air in from outside - that is part of the problem)

I am trying to get this info for Cummins as they and Foretravel have been playing phone tag the last 3 weeks ... figured I'd ask here and get an answer for them quicker here ;-)

If there is a document that would have any other specs on the fans/controller I'd be grateful as I will pass this along to them as well.

Thanks, Tim

P.S. Tomorrow I am trying, once again to coordinate a call between both parties in the hopes they can get our rig back to us.

Re: Fan RPM

Reply #1 – March 23, 2022, 10:19:14 pm

Are you saying one of your fans is sucking and the other one is blowing. The fans are
2 speed and I don't know which kind of controller you have. The high speed comes on
by temperature.

Re: Fan RPM

Reply #2 – March 23, 2022, 11:39:56 pm

Quote from: Kidspot – March 23, 2022, 09:46:29 pm

Currently they are spinning opposite directions and maxing out at 250 RPM

Sounds like a hydraulic hose is connected incorrectly at one of the motors, causing it to run "backwards".

A incorrectly connected hydraulic hose might also cause the fan speeds to be reduced.

Don't recall seeing any documents mentioned around here that would give specific fan speeds for your 2000 model U320. AFAIK, most Forum references to fan speed just say "high speed" or "low speed".

Keep trying to get with FOT - they would be the best source for specific fan RPM info and correct hydraulic hose plumbing diagram.

Re: Fan RPM

Reply #3 – March 23, 2022, 11:52:32 pm

Quote from: Kidspot – March 23, 2022, 09:46:29 pm

Anyone know what the hydraulic fan speed on the two cooling fans should be at high speed? 2000' U320 with Cummins ISM450. Currently they are spinning opposite directions and maxing out at 250 RPM (I know they are both supposed to be spinning the same way and drawing air in from outside - that is part of the problem)

I am trying to get this info for Cummins as they and Foretravel have been playing phone tag the last 3 weeks ... figured I'd ask here and get an answer for them quicker here ;-)

If there is a document that would have any other specs on the fans/controller I'd be grateful as I will pass this along to them as well.

Thanks, Tim

P.S. Tomorrow I am trying, once again to coordinate a call between both parties in the hopes they can get our rig back to us.

A picture of the hydraulic lines on the fans would tell me if they are the same as mine. The master motor passes the fluid to the slave motor so the flow would be in the same direction and so would the fans.

Re: Fan RPM

Reply #4 – March 24, 2022, 12:04:14 am

The two fan motors could have been installed so they counter rotate for better airflow (both pulling air through the radiator). Naturally, the blades would not be oriented at the same angle on both fans. Many twin engined aircraft have counter rotating engines/props for airflow but not for the same reason. Compare the blades on each fan.

Pierce

Re: Fan RPM

Reply #5 – March 24, 2022, 12:30:17 am

Boats with twin engines, the propellers turn in opposite directions. Cat bulldozers
the fans could be turned to suck or blow. It was so in the winter the operator could
keep warm having the fans suck.

Re: Fan RPM

Reply #6 – March 24, 2022, 06:33:29 am

250 RPM seems way too low even at idle. Here is a document FOT sent me for the U300. Almost all configurations should be close to 2000 RPM at WOT. (wide open throttle)

The reversed fan flow seems weird to me but FOT will have to answer that question.

see ya
ken

Re: Fan RPM

Reply #7 – March 24, 2022, 09:47:18 am

Trace the hose connection at the fans. One must be reversed.

Re: Fan RPM

Reply #8 – March 24, 2022, 09:56:50 am

Looks like I will play intermediary for a bit - FOT is sending me the specs that Cummins is wanting and I will get them to Cummins ... The phone tag is frustrating all 3 parties

Thank you for the help and specs provided here - appreciate your quick help.

- Tim

P.S. FOT did confirm both fans are to draw air in, and the fans should be spinning a lot faster than 250RPM (they are sending me actual specs shortly)

Re: Fan RPM

Reply #9 – March 24, 2022, 09:59:55 am

Yes, if one fan is sucking air from the outside (as they both should) and one is blowing air to the outside, check hose connections to the two fan motors.

Correct before addressing RPM.

Can you post pictures of the hose connections on the two fans?

Re: Fan RPM

Reply #10 – March 24, 2022, 10:02:16 am

It would enhance the Forum data base if you could post copies of whatever you get from FOT. There seems to be a "gap" in our group knowledge pertaining to this subject.

Re: Fan RPM

Reply #11 – March 24, 2022, 10:16:12 am

Tim I believe your year has the wax fan control valve. The fans speed is variable from low to high. The low background speed is adjustable. Definitely sounds like someone reversed the lines causing reverse rotation. The oil flow threw the wax valve adjusts the speed. More restriction causes higher fan speed. Less reduces speed. Fan speed will be low if temperature is low. Some hydraulic motor rotation can be reversed internally by reversing a flow plate. I haven't had a pump on our coach apart yet but has anyone had yours apart?
Scott

Re: Fan RPM

Reply #12 – March 24, 2022, 10:20:53 am

Quote from: dsd – March 24, 2022, 10:16:12 am

Fan speed will be low if temperature is low.
Scott

Yup, based on coolant temperature. It will not/should not go to high fan speed until several degrees above "thermostat fully open".

Re: Fan RPM

Reply #13 – March 24, 2022, 10:35:50 am

The 2001 and later with the electronic control could be commanded to hi buy removing control harness closing control solenoid.

Re: Fan RPM

Reply #14 – March 24, 2022, 05:01:41 pm

Quote from: Chuck & Jeannie – March 24, 2022, 10:02:16 am

It would enhance the Forum data base if you could post copies of whatever you get from FOT. There seems to be a "gap" in our group knowledge pertaining to this subject.

Here ya' go :-) Direct from Foretravel Tech dept:

Year Engine     Unit # Full Throttle RPM
1993    3116        4501    2769
1994    3116        4532    2849
1994     6V92        4566    2829
1995    M11        4848    3160
1995    8.3            4771    3161
1996    M11        4964    3009
1996    3126        4963    3009
1996    8.3            5023    2981
1996    3176        4965    3107
1998    M11/450    5425    3089
1998    ISC 8.3        5461    3036
1999    M11/450    5534    2934
1999    ISC 8.3        5655    2760
1999    M11/500    5548    2733
2000    ISC 8.3        5731    2655
2000    M11/450    5789    2769
2001    ISL8.8        5953    2657
2001    ISM/450        5954    2698
2002    ISM/450        6024    2870   24"fan blades
2002    ISL8.8        6118    2710
2003    ISL8.8        6194    2750
2003    M11        6229    2668

Re: Fan RPM

Reply #15 – March 24, 2022, 05:09:49 pm

Quote from: dsd – March 24, 2022, 10:16:12 am

Tim I believe your year has the wax fan control valve. The fans speed is variable from low to high. The low background speed is adjustable. Definitely sounds like someone reversed the lines causing reverse rotation. The oil flow threw the wax valve adjusts the speed. More restriction causes higher fan speed. Less reduces speed. Fan speed will be low if temperature is low. Some hydraulic motor rotation can be reversed internally by reversing a flow plate. I haven't had a pump on our coach apart yet but has anyone had yours apart?
Scott

I thought it had the danfoss control unit - which foretravel replaced last fall when we had it there for the bulkhead repair. And yes, both our fan pumps have been rebuilt in the last year - looks like we have to take it back to the last guys either way as it's still leaking and when Cummins sent it back to the factory they were told it was not the pump leaking ... this one was rebuilt in February, so still under warranty (one of the few things still under warranty lol)

Re: Fan RPM

Reply #16 – March 24, 2022, 05:14:02 pm

Quote from: wolfe10 – March 24, 2022, 10:20:53 am

Yup, based on coolant temperature. It will not/should not go to high fan speed until several degrees above "thermostat fully open".

it should have as it was up to 226° - they also unplugged the control unit, which should have put it into "hi" speed - both times it just ran at 250 rpm max ...

Today Chad from FOT was able to get the Cummins tech on the phone (he's been persistent trying to get him) and got him the specs I posted above - We (and lots of others) are praying they can get things running correctly as we are scheduled to leave for the west coast in a little over a week for work obligations...

Thanks again everyone for the advice posted - gives me some things to pass on to the Cummins crew as they finish up

Re: Fan RPM

Reply #17 – March 24, 2022, 05:45:59 pm

Formatted Kidspot's posting is attached

Re: Fan RPM

Reply #18 – March 24, 2022, 09:00:52 pm

Thank you, Barry & Cindy.

Re: Fan RPM

Reply #19 – March 25, 2022, 04:29:40 pm

Removing one line on the danfoss control unit and capping and plugging it would also command fans to hi speed.
Scott

Re: Fan RPM

Reply #20 – March 25, 2022, 06:49:56 pm

Sounds like we may have an answer - FOT and Cummins got on the phone together and it appears that when we had our rig in for the hydraulic fan motor replacement back in August (independent hydraulic shop that stayed open late and was hurrying to get us back on the road quickly since we are FT in our coach), they installed it backwards (thanks to those who suggested that as a possibility) ... Now they are trying to figure out why RPM are so low, but at least they know why one was running in reverse ... no wonder our overheating issue seemed to get a little worse this last trip across the country... Thanks again - I'll update once we have more answers...

Re: Fan RPM

Reply #21 – March 25, 2022, 07:16:06 pm

As discussed, straighten out the hose routing before concluding that fan speed is incorrect.

And, let us know if you have the electronic or wax valve hydraulic control for fan speed.

Re: Fan RPM

Reply #22 – March 26, 2022, 10:30:14 am

Quote from: wolfe10 – March 25, 2022, 07:16:06 pm

As discussed, straighten out the hose routing before concluding that fan speed is incorrect.

And, let us know if you have the electronic or wax valve hydraulic control for fan speed.

Per the control - Foretravel replaced the control unit last year - it was a $1k part - little silver box that sits on the frame at the back of the engine - Does that identify it as the electronic? I assumed so. And yes, I'll update once they have the hoses running in the right direction ...

Thanks again, Tim

Re: Fan RPM

Reply #23 – March 26, 2022, 11:06:44 am

The danfoss control unit with input from the ECM manages the desired fan speed when functioning normally with the solenoid valve installed on it. Typically fails to fans stuck in hi speed position with actually some benefits like cooler bedroom and improved retarder function by improved cooling temperature offset by the increased fuel consumption to run the fans in Hi.
Resolve your fan direction issue before continuing on trouble shooting and spending money needlessly. The Tech that installed your replacement danfoss control unit should of verified visually that fans would ramp up with engine at hi idle and disconnecting controller by seeing/hearing fan speed increase. During my original coach purchase I came across this problem as fans were maxed out all the time. Drove 7500 miles till i could perform repairs with the added cost of the fans running at hi.
Hydraulic fan controller DIY
This has worked well for me and I would duplicate again.
Resolve the rotation issue first . Your lines may or may not be routed correctly, ie motor could of been assembled to operate backward while apart possibly (unknown)

Scott

Re: Fan RPM

Reply #24 – April 02, 2022, 11:27:40 am

Once the hoses were routed correctly, both the fans spun in the same direction and it passed the heat test on the dyno at Cummins - The fans, according to the hydraulic shop that rebuild them (Weis?) will run at 1/2 engine RPM, when needed (above thermostat temp of 185°f) Due to this they were only running at 1000 RPM - They said the fans are capable of reaching 3000 RPM (as per the Foretravel document above) but they rarely will do so.

Hoping this is the last of our overheating issues - we pick up our coach on Monday after they get the step back from the body shop (a tow truck ran into it while it was at Cummins ) and I can do some prep work to get back on the road again. While we are grateful for family that let us stay in their guest room, after 4 months we are ready to be back in our home again!

Thanks again for all the advice and help here.

Aloha, Tim

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