Title: 2004 U320 ISM doesn't warm up
Post by: kgrover on January 31, 2025, 04:45:16 pm
Post by: kgrover on January 31, 2025, 04:45:16 pm
I'm having some issues with my 2004. I took it out last weekend and went to New Symrna Beach in Florida. Temperature was 20°F ish when we left Atlanta and didn't warm up much till we were well into Florida. The coolant temperature never got warm. I was cruising on the interstate at 75 mph, with a toad and the engine temp was barely 100°F. I also had very little heat from the dash. The transmission temperature was also very cold. The gauges, and two digital displays all matched temperatures. On the way back, I had ~175°F coolant temperature for half the trip, then it dropped for the second half.
So I figured the thermostat was stuck and I'd replace it when I got home.
I just replaced it today and it's still having the same issue. The original thermostat was not stuck, I checked it with some hot water and it worked fine. I did a stall test and held the engine at full power against the brakes and the engine warmed up very slowly then cooled back down.
The radiator hose coming out of the thermostat housing is warm, and I wasn't expecting that to have coolant flowing until it warmed up.
Does anyone have a diagram of how this is plumbed up? Or any suggestions? Is there another valve somewhere that should be closing? Thanks.
So I figured the thermostat was stuck and I'd replace it when I got home.
I just replaced it today and it's still having the same issue. The original thermostat was not stuck, I checked it with some hot water and it worked fine. I did a stall test and held the engine at full power against the brakes and the engine warmed up very slowly then cooled back down.
The radiator hose coming out of the thermostat housing is warm, and I wasn't expecting that to have coolant flowing until it warmed up.
Does anyone have a diagram of how this is plumbed up? Or any suggestions? Is there another valve somewhere that should be closing? Thanks.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: wolfe10 on January 31, 2025, 04:47:15 pm
Post by: wolfe10 on January 31, 2025, 04:47:15 pm
If you have an IR gun, use it to check temperature at the thermostat housing.
That will help you determine if this is a temperature or gauge issue.
That will help you determine if this is a temperature or gauge issue.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: kgrover on January 31, 2025, 05:58:14 pm
Post by: kgrover on January 31, 2025, 05:58:14 pm
They match.
If you have an IR gun, use it to check temperature at the thermostat housing.
That will help you determine if this is a temperature or gauge issue.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: dsd on January 31, 2025, 07:30:49 pm
Post by: dsd on January 31, 2025, 07:30:49 pm
So curious. Are the radiator fans running hiwhen cold. If you disconnect the plug on the controller they should ramp up to max speed cold
Hydraulic fan controller DIY (https://www.foreforums.com/index.php?topic=41024.0)
Hydraulic fan controller DIY (https://www.foreforums.com/index.php?topic=41024.0)
Title: Re: 2004 U320 ISM doesn't warm up
Post by: kgrover on February 01, 2025, 03:14:31 am
Post by: kgrover on February 01, 2025, 03:14:31 am
Yes, they are running full speed. Checking the sensors for that is on my list for today.
So curious. Are the radiator fans running hiwhen cold. If you disconnect the plug on the controller they should ramp up to max speed cold
Hydraulic fan controller DIY (https://www.foreforums.com/index.php?topic=41024.0)
Title: Re: 2004 U320 ISM doesn't warm up
Post by: wolfe10 on February 01, 2025, 08:36:57 am
Post by: wolfe10 on February 01, 2025, 08:36:57 am
While I completely agree that running the fan on high is not desirable from a HP, MPG, noise and dust standpoint, unless the thermostat (or alternate plumbing) sends coolant to the radiator, the amount of air passing through the radiator should not be a big factor in coolant temperature in the engine.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: kgrover on February 01, 2025, 08:58:44 am
Post by: kgrover on February 01, 2025, 08:58:44 am
4k
That was my thought too. Sensors measured 4k ohm at 45°F, which is about right according to the chart,
While I completely agree that running the fan on high is not desirable from a HP, MPG, noise and dust standpoint, unless the thermostat (or alternate plumbing) sends coolant to the radiator, the amount of air passing through the radiator should not be a big factor in coolant temperature in the engine.
That was my thought too. Sensors measured 4k ohm at 45°F, which is about right according to the chart,
Title: Re: 2004 U320 ISM doesn't warm up
Post by: wolfe10 on February 01, 2025, 10:04:09 am
Post by: wolfe10 on February 01, 2025, 10:04:09 am
Yes, another way to look at cooling through the radiator:
Engine temperature should be the same with fan on high or low (unless under high load when it may rise somewhat).
Engine temperature should be the same if 20 degrees F or 100 degrees F (unless high load when it may rise somewhat).
Fan speed and ambient temperatures should not impact coolant temperature. Extreme example is Ice Road Truckers who often drove in -20 degrees F. Their engine temperatures were as they should be.
Engine temperature should be the same with fan on high or low (unless under high load when it may rise somewhat).
Engine temperature should be the same if 20 degrees F or 100 degrees F (unless high load when it may rise somewhat).
Fan speed and ambient temperatures should not impact coolant temperature. Extreme example is Ice Road Truckers who often drove in -20 degrees F. Their engine temperatures were as they should be.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: Dennis H on February 01, 2025, 11:55:21 am
Post by: Dennis H on February 01, 2025, 11:55:21 am
Look for other sources of heat loss from the engine. Start with the interior heating system and the hydronic heating system. Be sure that there is not flow from the heating loop into the water tank. A pump running that shouldn't or one of the systems check valves.
Is there a combination of engine coolant and the external oil cooler for the transmission? I'm still trying to figure this out on mine. I am finding it amazing that the transmission always gets close to engine temperature even at low speeds and low outside temps. There is likely a thermostat or other flow control for the external cooler.
I will suggest that this is a priority to get resolved. Operating the engine in this manner can be damaging. There is often mention of wanting service records and stuff for the value of a used coach or a purchase decision. Events like this often happen and quickly make how often the oil was changed meaningless. Rare is the engine or transmission that has not suffered a trauma.
Is there a combination of engine coolant and the external oil cooler for the transmission? I'm still trying to figure this out on mine. I am finding it amazing that the transmission always gets close to engine temperature even at low speeds and low outside temps. There is likely a thermostat or other flow control for the external cooler.
I will suggest that this is a priority to get resolved. Operating the engine in this manner can be damaging. There is often mention of wanting service records and stuff for the value of a used coach or a purchase decision. Events like this often happen and quickly make how often the oil was changed meaningless. Rare is the engine or transmission that has not suffered a trauma.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: kgrover on February 01, 2025, 07:08:55 pm
Post by: kgrover on February 01, 2025, 07:08:55 pm
Fan controller is bad. It turns off the fan for about 10 seconds if you unplug it and plug it back in, but then the driver starts to fail and the fan turns back on. I tested it on my bench. It worked once for a bit, then went back to failing. With the fan not running it does warm up, but drops as soon as I turned the fan on. I'll put a different controller on, I have multiple on my bench from my job.
Where is the coolant sensor on this engine? I can't seem to find it.
Where is the coolant sensor on this engine? I can't seem to find it.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: Dennis H on February 01, 2025, 09:52:01 pm
Post by: Dennis H on February 01, 2025, 09:52:01 pm
The fan may also be turned on for some speed with the AC compressor. AC should also be called for with defrost.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: kgrover on February 02, 2025, 05:26:26 am
Post by: kgrover on February 02, 2025, 05:26:26 am
The fan may also be turned on for some speed with the AC compressor. AC should also be called for with defrost.
The A/C condenser is on the other side and has it's own fan. The controller is monitoring coolant and intake temperature.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: Dennis H on February 02, 2025, 09:34:31 am
Post by: Dennis H on February 02, 2025, 09:34:31 am
The A/C condenser is on the other side and has it's own fan. The controller is monitoring coolant and intake temperature.
Forgot about the AC condenser being separate. My 08 has it in front of the charger air cooler alongside the transmission cooler.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: dsd on February 02, 2025, 12:42:50 pm
Post by: dsd on February 02, 2025, 12:42:50 pm
Yes, another way to look at cooling through the radiator:
Engine temperature should be the same with fan on high or low (unless under high load when it may rise somewhat).
Engine temperature should be the same if 20 degrees F or 100 degrees F (unless high load when it may rise somewhat).
Fan speed and ambient temperatures should not impact coolant temperature. Extreme example is Ice Road Truckers who often drove in -20 degrees F. Their engine temperatures were as they should be.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: wolfe10 on February 02, 2025, 12:49:04 pm
Post by: wolfe10 on February 02, 2025, 12:49:04 pm
So why do they cover the radiator?
Even with no fan -20 degrees F over the engine (front engine/front radiator, so at 50 MPH> 50 MPH wind through the engine room) can over-cool it even with no or little cooling in the radiator.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: fourdayoff on February 02, 2025, 03:56:27 pm
Post by: fourdayoff on February 02, 2025, 03:56:27 pm
As Kgrover has found through his own diagnoses those fans are able to shed allot of heat away from the engine. You can take a look at the wax valve conversion a few of us on here have done. I have set mine up so that I can run either one. Jim.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: kgrover on February 10, 2025, 05:20:39 pm
Post by: kgrover on February 10, 2025, 05:20:39 pm
I setup a new fan controller to replace the Sauer-Danfoss FDCA controller that failed. The fans are working great now. I set the fan on/off temperatures to the chart in 
, page 483.
The first chart is where I was loading the engine up by holding the brakes with it in gear to get some heat into it. The green line is the temperature from the engine ECM, the blue line is from the fan controller. The sensor for the fan controller is farther back in the side of the block. The engine ECM reads the temperature at the thermostat housing. 100% fan, means the command is 100% and the fan is off since the solenoid is normally open, it needs current to close and stop the fan.
Second chart is at high idle with the A/C running to get a little more load on the engine. You can see the temperature climb and the fan ramp up and down to match it. It looks like it's working pretty well.
Last picture is the controller installed where the original one was. I need to work on the mounting bracket a little more, but it worked for testing.
This with the new thermostat should fix my over cooling issue.
There is also a TSB from Cummins on the over cooling issue where the thermostats can stick open.
QuickServe Online (https://quickserve.cummins.com/qs3/pubsys2/xml/en/tsb/2013/tsb130055.html)
, page 483. The first chart is where I was loading the engine up by holding the brakes with it in gear to get some heat into it. The green line is the temperature from the engine ECM, the blue line is from the fan controller. The sensor for the fan controller is farther back in the side of the block. The engine ECM reads the temperature at the thermostat housing. 100% fan, means the command is 100% and the fan is off since the solenoid is normally open, it needs current to close and stop the fan.
Second chart is at high idle with the A/C running to get a little more load on the engine. You can see the temperature climb and the fan ramp up and down to match it. It looks like it's working pretty well.
Last picture is the controller installed where the original one was. I need to work on the mounting bracket a little more, but it worked for testing.
This with the new thermostat should fix my over cooling issue.
There is also a TSB from Cummins on the over cooling issue where the thermostats can stick open.
QuickServe Online (https://quickserve.cummins.com/qs3/pubsys2/xml/en/tsb/2013/tsb130055.html)
Title: Re: 2004 U320 ISM doesn't warm up
Post by: steve on February 10, 2025, 06:03:37 pm
Post by: steve on February 10, 2025, 06:03:37 pm
Awesome write up ^.^d
I've attached the TSB from the above link
I've attached the TSB from the above link
Title: Re: 2004 U320 ISM doesn't warm up
Post by: dsd on February 13, 2025, 09:04:09 pm
Post by: dsd on February 13, 2025, 09:04:09 pm
Did you go to something different to the Sauer-Danfoss?
I setup a new fan controller to replace the Sauer-Danfoss FDCA controller that failed. The fans are working great now. I set the fan on/off temperatures to the chart in
The first chart is where I was loading the engine up by holding the brakes with it in gear to get some heat into it. The green line is the temperature from the engine ECM, the blue line is from the fan controller. The sensor for the fan controller is farther back in the side of the block. The engine ECM reads the temperature at the thermostat housing. 100% fan, means the command is 100% and the fan is off since the solenoid is normally open, it needs current to close and stop the fan.
Second chart is at high idle with the A/C running to get a little more load on the engine. You can see the temperature climb and the fan ramp up and down to match it. It looks like it's working pretty well.
Last picture is the controller installed where the original one was. I need to work on the mounting bracket a little more, but it worked for testing.
This with the new thermostat should fix my over cooling issue.
There is also a TSB from Cummins on the over cooling issue where the thermostats can stick open.
QuickServe Online (https://quickserve.cummins.com/qs3/pubsys2/xml/en/tsb/2013/tsb130055.html)
Title: Re: 2004 U320 ISM doesn't warm up
Post by: kgrover on February 14, 2025, 05:39:16 am
Post by: kgrover on February 14, 2025, 05:39:16 am
Parker IQAN MC41 (https://ph.parker.com/us/en/product/iqan-mc4x-master-controllers-for-mobile-hydraulic-systems-and-vehicles/20085111)
I used an IQAN MC41 controller mainly because I have them and the software to program it. I'm the Application engineer for Mobile electronics for Parker-Hannifin for the South East. So I had one on my bench and it's really easy to setup. It's got more I/O than is needed for just a fan controller, but it works great. I used the existing sensors and control valve. I also tied it into the CAN network for the coach so it can send error messages up to the Bluefire display if anything goes wrong.
I used an IQAN MC41 controller mainly because I have them and the software to program it. I'm the Application engineer for Mobile electronics for Parker-Hannifin for the South East. So I had one on my bench and it's really easy to setup. It's got more I/O than is needed for just a fan controller, but it works great. I used the existing sensors and control valve. I also tied it into the CAN network for the coach so it can send error messages up to the Bluefire display if anything goes wrong.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: Digger337 on February 14, 2025, 11:01:20 pm
Post by: Digger337 on February 14, 2025, 11:01:20 pm
I'm having some issues with my 2004. I took it out last weekend and went to New Symrna Beach in Florida. Temperature was 20°F ish when we left Atlanta and didn't warm up much till we were well into Florida. The coolant temperature never got warm. I was cruising on the interstate at 75 mph, with a toad and the engine temp was barely 100°F. I also had very little heat from the dash. The transmission temperature was also very cold. The gauges, and two digital displays all matched temperatures. On the way back, I had ~175°F coolant temperature for half the trip, then it dropped for the second half.
So I figured the thermostat was stuck and I'd replace it when I got home.
I just replaced it today and it's still having the same issue. The original thermostat was not stuck, I checked it with some hot water and it worked fine. I did a stall test and held the engine at full power against the brakes and the engine warmed up very slowly then cooled back down.
The radiator hose coming out of the thermostat housing is warm, and I wasn't expecting that to have coolant flowing until it warmed up.
Does anyone have a diagram of how this is plumbed up? Or any suggestions? Is there another valve somewhere that should be closing? Thanks.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: kgrover on May 01, 2025, 09:46:44 am
Post by: kgrover on May 01, 2025, 09:46:44 am
Just crossed into Arizona from Georgia on our way to Mexico to get the 2004 painted and the fan controller is working great. I added in the Retarder Temperature that the transmission is reporting and I have the fan set to ramp up if that gets warm too. Coolant temp and Intake temps have been right where they should be for the whole trip. If anyone needs any more information on this setup, or help setting something like this up on theirs, just let me know.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: dsd on May 04, 2025, 04:34:31 pm
Post by: dsd on May 04, 2025, 04:34:31 pm
Just crossed into Arizona from Georgia on our way to Mexico to get the 2004 painted and the fan controller is working great. I added in the Retarder Temperature that the transmission is reporting and I have the fan set to ramp up if that gets warm too. Coolant temp and Intake temps have been right where they should be for the whole trip. If anyone needs any more information on this setup, or help setting something like this up on theirs, just let me know.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: Jan & Richard on May 04, 2025, 09:25:31 pm
Post by: Jan & Richard on May 04, 2025, 09:25:31 pm
I have noticed that under odd circumstances you can exceed IAT and having it being monitored is a good thing.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: Big Al on May 05, 2025, 08:25:58 am
Post by: Big Al on May 05, 2025, 08:25:58 am
So for a Cummins M-11/ISM, what is the acceptable temperature range. Input Air Temperature is one of the parameters that I monitor but I have never seen posted what that temperature should be. I generally see an IAT of about 20 degrees above ambient air temperature.
My IAT is normally around 15-20 degrees above ambient air temperature also.
I think that's pretty standard.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: kgrover on May 06, 2025, 08:08:22 pm
Post by: kgrover on May 06, 2025, 08:08:22 pm
So do you still have the IAT temp input? I have noticed that under odd circumstances you can exceed IAT and having it being monitored is a good thing.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: kgrover on May 06, 2025, 08:23:39 pm
Post by: kgrover on May 06, 2025, 08:23:39 pm
So for a Cummins M-11/ISM, what is the acceptable temperature range. Input Air Temperature is one of the parameters that I monitor but I have never seen posted what that temperature should be. I generally see an IAT of about 20 degrees above ambient air temperature.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: dsd on May 07, 2025, 11:38:36 am
Post by: dsd on May 07, 2025, 11:38:36 am
So for a Cummins M-11/ISM, what is the acceptable temperature range. Input Air Temperature is one of the parameters that I monitor but I have never seen posted what that temperature should be. I generally see an IAT of about 20 degrees above ambient air temperature.
Title: Re: 2004 U320 ISM doesn't warm up
Post by: Geodmann on August 10, 2025, 10:08:00 pm
Post by: Geodmann on August 10, 2025, 10:08:00 pm
Coolant temp and Intake temps have been right where they should be for the whole trip.
Ken, what do you consider to be "right where they should be"? 180 degrees? Where are you reading coolant temp? From your Bluefire?
Title: Re: 2004 U320 ISM doesn't warm up
Post by: kgrover on August 11, 2025, 06:08:10 am
Post by: kgrover on August 11, 2025, 06:08:10 am
The below numbers and chart are from the Cummins troubleshooting manual.
I have the fan set to start ramping up at 195°F and it's on full by 203°F. That's a little bit lower then Cummins spec, but works well. On the trip back from Mexico, she was at full throttle for about 20 minutes straight climbing some grades and the engine temp held at 200°F.
The bluefire is reading the coolant temp from the Cummins ECM. I can also see the coolant temp and intake temp from the fan controller sensors. They are in a different location that the engine sensors. If I could get someone from Bluefire to give me the list of messages they are reading, I could add more information to that screen, but I've had no luck so far.
The chart shows some data from early testing. The blue line is the sensor the fan controller is reading. The green line is what the engine ECM is reporting. The Engine reads the temperature at the thermostat housing. The fan controller sensor is in the side of the block towards the rear of the engine. I've tweaked the settings since this graph. I was adjusting as we were driving out to Mexico. My buddy was driving, not me.
(https://www.foreforums.com/index.php?action=dlattach;topic=49013.0;attach=139619)
I have the fan set to start ramping up at 195°F and it's on full by 203°F. That's a little bit lower then Cummins spec, but works well. On the trip back from Mexico, she was at full throttle for about 20 minutes straight climbing some grades and the engine temp held at 200°F.
The bluefire is reading the coolant temp from the Cummins ECM. I can also see the coolant temp and intake temp from the fan controller sensors. They are in a different location that the engine sensors. If I could get someone from Bluefire to give me the list of messages they are reading, I could add more information to that screen, but I've had no luck so far.
The chart shows some data from early testing. The blue line is the sensor the fan controller is reading. The green line is what the engine ECM is reporting. The Engine reads the temperature at the thermostat housing. The fan controller sensor is in the side of the block towards the rear of the engine. I've tweaked the settings since this graph. I was adjusting as we were driving out to Mexico. My buddy was driving, not me.
Code: [Select]
Cooling System
Coolant Capacity (engine only) ............ ,..................................................................................... 9.5 liters [10 qt]
Standard Modulating Thermostat Range .................................................................... 82 to 93°C [180 to 200°F]
Cylinder Block Coolant Pressure (pressure cap removed):
Minimum
Closed Thermostat - 1800 rpm - No Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 kPa [20 psi]
Maximum
Closed Thermostat ... 275 kPa [40 psi]
Maximum Allowable Operating Coolant Temperature ...................................................................... 100°C [212°F]
Minimum Recommended Operating Coolant Temperature ................................................................ 70°C [160°F]
Minimum Recommended Pressure Cap .......................................................................................... 48 kPa [7 psi]
Maximum Allowable Coolant Flow to Accessories (liters/minute [gpm]) ................................... 75.7 Liters [20 gal]
Coolant Sensing Fan Control:
On ... 96°C [205°F]
Off ... 91°C [195°F]
(https://www.foreforums.com/index.php?action=dlattach;topic=49013.0;attach=139619)
Title: Re: 2004 U320 ISM doesn't warm up
Post by: Geodmann on August 13, 2025, 01:32:08 pm
Post by: Geodmann on August 13, 2025, 01:32:08 pm
Very good information and thanks for providing. So the manual says the t-stat should modulate from 180-200F, the minimum and maximum coolant temps are 160F and 212F, and the fan controller should be on at 205F and off at 195F.
Is the Sauer Danfoss controller adjustable? Fan on at 205 seems really high if you don't expect the coolant to get over 212.
I feel better knowing that it's OK to run the engine as low as 160 but I will study my problem some more to try to determine if my thermostat is stuck open or my fan just comes on too low. If the Sauer Danfoss control is adjustable, hopefully someone can provide some instruction.
Thanks!
Is the Sauer Danfoss controller adjustable? Fan on at 205 seems really high if you don't expect the coolant to get over 212.
I feel better knowing that it's OK to run the engine as low as 160 but I will study my problem some more to try to determine if my thermostat is stuck open or my fan just comes on too low. If the Sauer Danfoss control is adjustable, hopefully someone can provide some instruction.
Thanks!
Title: Re: 2004 U320 ISM doesn't warm up
Post by: Beerslayer_24 on August 13, 2025, 03:01:03 pm
Post by: Beerslayer_24 on August 13, 2025, 03:01:03 pm
Hi George,
My electronic fan controller failed and I asked FOT for information, they sent me these two technical bulletins. The parameter setup instruction start on page 23, some special equipment is required.
I hope this helps you.
Bob Carbone
Grand Cane, LA
My electronic fan controller failed and I asked FOT for information, they sent me these two technical bulletins. The parameter setup instruction start on page 23, some special equipment is required.
I hope this helps you.
Bob Carbone
Grand Cane, LA