'17 3500 Rad cooling fan does not come on with hot engine. Bad fan relay?

[Ozymandias]

What I dont see here in this thread is the problem?

In general the newer the vehicle the hotter the engine runs because of the emissions standards.

220f is within the working parameter of this engine and all below 245f is okay to run for some time.
230f I'd run all day long if working it hard.

That's why we have a pressurized cooling system.
225f was once a critical temp back in the days with open systems, they are long gone.

 

[EZeis]

Is there an actual issue? My 2018 3500 fan doesn't come up to speed enough to hear it until the coolant temp is pretty high. Much higher than my 07 5.9 did. I don't recall the coolant temp but it was in the 220's I believe, enough to shock me till I realized it was normal. If the fan is coming up on speed when the ac runs, that means the clutch, circuit and pcm are working. The cel would light if the fan didn't match what the pcm is calling for. There are also codes for other fan clutch issues. I didn't see any mention of checking for codes and if there are any. Is this a new issue or always been that way? How hot does it get? Hot enough to give an overheat code? Go into limp?

Is there more than one coolant temp sensor? If so, one could be off. Dash or pcm sensor could be lying.

Note, they run hotter thermostats too.

I believe you're not use to these newer trucks running much hotter.

Earl

 

[AH64ID]

Most fan codes are soft codes and won’t set a CEL. He said they were checked in his other thread, but there were also questions about the reliability of the tech.

Codes need to be checked again, and really it just needs to go to the dealer. If it’s not a fan clutch, thou likely it is, it will involve some decent troubleshooting.

What I dont see here in this thread is the problem?

In general the newer the vehicle the hotter the engine runs because of the emissions standards.

220f is within the working parameter of this engine and all below 245f is okay to run for some time.
230f I'd run all day long if working it hard.

That's why we have a pressurized cooling system.
225f was once a critical temp back in the days with open systems, they are long gone.

The fan should be 100% by 220°, and even with the emissions stuff Cummins still lists 225° as the max allowable temp for a 190° thermostat on an engine with EGR.

The trucks run a little warmer than the 5.9 with the same thermostat, but not much. With stock fan settings on both my 05 only ran a couple degrees cooler with similar power, at/near WOT, towing up steep grades.

Here is the fan rpm demand chart that I posted in his other thread. 220° is asking for a lot of rpm.

 

[EZeis]

The fan should be 100% by 220°, and even with the emissions stuff Cummins still lists 225° as the max allowable temp for a 190° thermostat on an engine with EGR.

The trucks run a little warmer than the 5.9 with the same thermostat, but not much. With stock fan settings on both my 05 only ran a couple degrees cooler with similar power, at/near WOT, towing up steep grades.

Here is the fan rpm demand chart that I posted in his other thread. 220° is asking for a lot of rpm.


View attachment 126219

Believe that's dated information. Pretty sure they run 200F thermostats, not 190. My 2018 runs much higher coolant temp than my 07 5.9. I believe the OP just isn't use to that. The truck will set codes and should go into limp if it's getting too high on coolant temps. OP never mentioned a cel or having codes. The first step to troubleshooting.


Earl

 

[AH64ID]

Believe that's dated information. Pretty sure they run 200F thermostats, not 190. My 2018 runs much higher coolant temp than my 07 5.9. I believe the OP just isn't use to that. The truck will set codes and should go into limp if it's getting too high on coolant temps. OP never mentioned a cel or having codes. The first step to troubleshooting.


Earl

My 2018 absolutely has a 190° thermostat. 200° where used for a short time but when SCR came out the thermostat went back to 190°.

A lot of the reason the 6.7 runs hotter is the cooling capacity is lower than a 5.9, about 5.4 quarts lower just from what the block holds.

The data on temps is current from Cummins. Nothing has changed in regards to the amount of heat rejection a cooling system needs to have for a specific application.

The fan rpm chart is from a 2017 stock file.

IMO there is something wrong with the OP’s truck. 220° should have a screaming fan! Cessna screaming. I will see 215-218° towing hard up a steep grade but no hotter, and that’s at/near WOT. My 05 did 215° up the same grades until I reprogrammed the fan.

 

[EZeis]

Just noticed he has a 2017. If there is an actual issue, shouldn't it be covered under warranty and/or max care warranty if he has it?

Thanks,
Earl

 

[EZeis]

My 2018 absolutely has a 190° thermostat. 200° where used for a short time but when SCR came out the thermostat went back to 190°.

A lot of the reason the 6.7 runs hotter is the cooling capacity is lower than a 5.9, about 5.4 quarts lower just from what the block holds.

The data on temps is current from Cummins. Nothing has changed in regards to the amount of heat rejection a cooling system needs to have for a specific application.

The fan rpm chart is from a 2017 stock file.

IMO there is something wrong with the OP’s truck. 220° should have a screaming fan! Cessna screaming. I will see 215-218° towing hard up a steep grade but no hotter, and that’s at/near WOT. My 05 did 215° up the same grades until I reprogrammed the fan.

I'm on the nothing is wrong side. If his truck is running too hot, why no codes? Why no limp?

My 18 gets some pretty high coolant temps. Scared me a couple times but I kept my foot in it to the floor and the truck took care of itself. Never overheated. That fan at high rpm is loud as ****!

I'm going it need codes before I agree there is something wrong.

Earl

 

[Ozymandias]

Most fan codes are soft codes and won’t set a CEL. He said they were checked in his other thread, but there were also questions about the reliability of the tech.

Codes need to be checked again, and really it just needs to go to the dealer. If it’s not a fan clutch, thou likely it is, it will involve some decent troubleshooting.



The fan should be 100% by 220°, and even with the emissions stuff Cummins still lists 225° as the max allowable temp for a 190° thermostat on an engine with EGR.

The trucks run a little warmer than the 5.9 with the same thermostat, but not much. With stock fan settings on both my 05 only ran a couple degrees cooler with similar power, at/near WOT, towing up steep grades.

Here is the fan rpm demand chart that I posted in his other thread. 220° is asking for a lot of rpm.


View attachment 126219

But 220f gives only 2400rpm, that's shy above 50% of it's ability and shows clearly that Cummins states 220f as fine to run for as long as one wants it.

I'm with Earl, the truck will set a code if anything is out of spec with the Fan, they do this since they went to the PWM Fan.
I myself had a code after fording a river were the water sloweddown the Fan enough, it went into limp mode right away.

I can't believe there is anything wrong with this truck.

 

[Ozymandias]

The OP should get AlfaOBD so we can see what's actually going on, what the ECM is calling for.

 

[AH64ID]

The fan codes are generally soft codes thou, meaning no CEL. Even on a 3rd gen a slow fan won't set a hard code under most circumstances, it's a big reason so many trucks are running around with failing/failed clutches.

No, the truck won't go into limp mode until you get around 245° or higher... basically a serious overheat condition. It's like the old AT TEMP HI lights, they weren't warnings for high temp, they were "it's too late" lights.

Also, 225° is the max allowable but that doesn't mean that damage happens at 226°... it just means that there is more heat being created than the cooling system can efficiently handle.. so something is wrong or undersized, on a OEM system that should mean something is wrong.

Yes, it should be under warranty but the OP doesn't have a local dealer he trusts.

Also, yes the fan is LOUD... yet the OP isn't hearing it when his coolant temp is 220°, yet he can hear it cycle lightly with the A/C. IIRC the min fan rpm for A/C is 300 rpm.

220° is more than 2400 rpms, as the commanded rpms go from 2400 @ 219.2 to 3600 @222.8. That's an increase of 611 rpm/degF, or 220.0 is calling for 2889 rpms which is SCREAMING. Look at the rpm chart, they really start ramping rpms at 217.4° (103°C), which corresponds with the 218° I'll occasionally see as a max. The fan is VERY effective at those rpms. Nothing about that chart makes me think that Cummins is ok with 220° continuous, 217.4° is where they want to stop ECT from climbing. 220° won't hurt anything, but they are really trying to bring it down at that point.

I'll have to look tonight, but I don't think the max allowable fan rpm is over 4000... somewhere in the 3000's comes to mind, but I'll have to look.


You guys may not thing anything is wrong, but what the OP is describing is FAR from normal for his truck.

 

[Wiredawg]

Friends,

Based upon info I posted, starting MY2010 Ram installs 200°F thermostats, and the high temp threshold is 230°. Some info is there. you just have to READ it.

I recall seeing coolant temps inthe low 220s, I've towed 34KLbs in 110°F temps pulling some big grades out West. The cooling systems on these trucks is amazing. I dont hear my fan kicking that often, but when it does. it sounds like an aircraft turbofan.

One thing many have pointed out, would be helpful to have baseline and trend data, outside temps, coolant temps, truck load, coolant temp changes, etc.

There isn't good troubleshooting info in the manual and if you are not proficient at automotive electrical testing, you may be better off taking to a dealer. Sadly, it's more common to throw parts at it.

As has been also stated, it's possible it IS the fan, but would be sad if it turned out not to be. As several posts in at least two threads, it looks like you're at a decision point to do something.

I'm retired, although I'm backed up on vehicle and home projects, and will look further in my manual.

One thing I'd like to tell you and others who plan on working on their trucks... buy the manual! As lacking as it is, it still better than nothing. When I travel, I carry my laptop, so have access to it.

Cheers, Ron

Cheets, Ron

 

[AH64ID]

Friends,

Based upon info I posted, starting MY2010 Ram installs 200°F thermostats, and the high temp threshold is 230°. Some info is there. you just have to READ it.

Yes in MY2010 they did install 200°F thermostats, but that only lasted thru MY2012. For 2013, with the introduction of SCR, they went back to 190°F thermostats.

It really would be worth the OPs time to let a dealership handle it.

 

[Wiredawg]

I don't think that this will work out because then the command and return Fan speed will be out of spec and the truck will go to limp mode.

Ozy, it could throw it into limp mode, I doubt it...but if it did, it should self clear after all parameters are back to normal. The thing about troubleshooting these trucks at home without the scan tool, is you can't change parameters on the fly, or go into pre-programmed test mode, so what else you gonna do? The point is, you might get it to go to engage, and verify it's good or not.

I'm not disagreeing with you, but I'm GUESSING the PCM applies voltage to the fan based upon inputs from the sensors, including the fan.

Cheers. Ron

 

[Ozymandias]

The fan codes are generally soft codes thou, meaning no CEL. Even on a 3rd gen a slow fan won't set a hard code under most circumstances, it's a big reason so many trucks are running around with failing/failed clutches.

No, the truck won't go into limp mode until you get around 245° or higher... basically a serious overheat condition. It's like the old AT TEMP HI lights, they weren't warnings for high temp, they were "it's too late" lights.

Also, 225° is the max allowable but that doesn't mean that damage happens at 226°... it just means that there is more heat being created than the cooling system can efficiently handle.. so something is wrong or undersized, on a OEM system that should mean something is wrong.

Yes, it should be under warranty but the OP doesn't have a local dealer he trusts.

Also, yes the fan is LOUD... yet the OP isn't hearing it when his coolant temp is 220°, yet he can hear it cycle lightly with the A/C. IIRC the min fan rpm for A/C is 300 rpm.

220° is more than 2400 rpms, as the commanded rpms go from 2400 @ 219.2 to 3600 @222.8. That's an increase of 611 rpm/degF, or 220.0 is calling for 2889 rpms which is SCREAMING. Look at the rpm chart, they really start ramping rpms at 217.4° (103°C), which corresponds with the 218° I'll occasionally see as a max. The fan is VERY effective at those rpms. Nothing about that chart makes me think that Cummins is ok with 220° continuous, 217.4° is where they want to stop ECT from climbing. 220° won't hurt anything, but they are really trying to bring it down at that point.

I'll have to look tonight, but I don't think the max allowable fan rpm is over 4000... somewhere in the 3000's comes to mind, but I'll have to look.


You guys may not thing anything is wrong, but what the OP is describing is FAR from normal for his truck.

It will go to limp mode as soon as it knows that there is something seriously wrong with the Fan, the ECM is smart to know that with a malfunction Fan it can not keep up with the heat dissipation.
It happened to me.

But - the GEN3 does not go to limp with the Fan disconnected, what is hilarious.

I say it again, he needs AlfaOBD.

 

[AH64ID]

It will go to limp mode as soon as it knows that there is something seriously wrong with the Fan, the ECM is smart to know that with a malfunction Fan it can not keep up with the heat dissipation.
It happened to me.

But - the GEN3 does not go to limp with the Fan disconnected, what is hilarious.

I say it again, he needs AlfaOBD.

Yes they can with something seriously wrong, but a slow fan is not considered serious by the ECM. I've seen numerous soft codes for slow fans on 3rd gens. None of them had limp mode or CEL's. They will overheat on a soft code and still not set a CEL from what I've seen.

AlfaOBD is a great tool. If he can confirm or rule out the fan clutch it would dictate whether he needs to go to the dealership or not.

 

[Ozymandias]

Yes they can with something seriously wrong, but a slow fan is not considered serious by the ECM. I've seen numerous soft codes for slow fans on 3rd gens. None of them had limp mode or CEL's. They will overheat on a soft code and still not set a CEL from what I've seen.

AlfaOBD is a great tool. If he can confirm or rule out the fan clutch it would dictate whether he needs to go to the dealership or not.

On the GEN3 I think it depends how much off the Fan is from the desired speed. Like said I went into the river and it lit the CEL instantly and went into limp the same moment, there was no delay.

But we both know that GEN3 is stone age and I expect a more sophisticated behavior from a model 15 years younger.

We'll see how that turns out once he can do a proper diagnosis. Without that it's all guessing and reading clouds - and spending money on that is, in my opinion, even worse.
Sure we all try our best to help, and often that works out, but sometimes we need more info on a certain problem. And that means the TO needs to buy AlfaOBD.

 

[Wiredawg]

Please read below:

P0116-ENGINE COOLANT TEMPERATURE SENSOR PERFORMANCE
For a complete wiring diagram, refer to the Wiring Information.


Theory of Operation
The Engine Coolant Temperature Sensor (ECT) is located near the thermostat housing and is used to measure the engine coolant temperature. The Engine Coolant Temperature Sensor receives 5-Volts and a sensor ground from the PCM. The PCM monitors the change in voltage to determine the coolant temperature. There are two parts to this fault code, a key on check and a rationality check. After an eight hour cold soak, at key on the readings for the Inlet Air Temperature, Intake Air Temperature and Engine Coolant Temperature Sensors are all compared. If the temperatures differ more than a calibrated amount, then the appropriate sensor fault code would be recorded. The key on monitor is disabled for ambient temperatures below 20°F. This monitor looks for all the sensors to be grouped on one temperature or, in the case that the monitor fails, two sensors grouped at one temperature and one outlier. In the case that all three sensor values are distributed over a range of temperatures this diagnostic will not run. A block heater is one possible cause of such a distribution. The PCM rationality check looks at the temperature reading from the sensor over time and ensures that it changes with engine running. If the sensor reading does not change over a calibrated time limit, the fault will be recorded. Both the key-on and rationality portions of this monitor require that the diagnostic fails in two consecutive drive cycles before the MIL lamp is lit. The ETC lamp will also be illuminated. During this time the PCM uses a default value for the Coolant Temperature Sensor. The PCM turns off the MIL lamp when the diagnostic runs and passes in four consecutive drive cycles.

• When Monitored:
  While the engine is running.
  
  
• Set Condition:
  The Powertrain Control Module (PCM) does not read a change in value from the sensor over time.

Much of the testing on the system is done using the scan tool... But if I'm reading correctly, if you are experiencing a cooling system failure, any of the three source temp sensors out of range for two driving cycles, WILL set a hard MIL.

Cheers, Ron

 

[AH64ID]

The ECT sensor is likely accurate, but even if it was not the fan should still be commanded off the false reading as there is only 1 ECT sensor.

 

[EZeis]

OP ever check for codes? I see no mention of it. It's extremely important. If he hasn't, why is he working on it? Unless he likes spending money on parts throwing. Also curious as to why he's not letting the dealer work on it under warranty? Is his scan tool showing the same coolant temp as the dash? Maybe his dash is lying?

Earl

 

[AH64ID]

OP ever check for codes? I see no mention of it. It's extremely important. If he hasn't, why is he working on it? Unless he likes spending money on parts throwing. Also curious as to why he's not letting the dealer work on it under warranty? Is his scan tool showing the same coolant temp as the dash? Maybe his dash is lying?

Earl

He mentioned in the other thread that it was checked for codes by his tech and none were present.

He also mentioned in the other thread that it's out of the 3/36 and the fan clutch is not covered under the powertrain warranty... which is odd but not surprising with FCA.