Failed Fan Clutch, I think.

[Loren]

My engine fan clutch seems to have failed. From the research I’ve done here it looks like this is a common problem and the repair is to replace the fan clutch itself.

My truck is a 2016, 3500 single-rear-wheel, with the HO engine and an Aisin transmission.

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First: How likely is it that my problem is somewhere else? I’m ASSUMING that it’s the clutch, but what are the chances it’s not?

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Second: What is involved in changing the fan clutch?

It looks like there are four nuts on studs that hold the fan shroud in place, but it also looks like removing those nuts won’t allow me to actually remove the shroud. There doesn’t appear to be any way to get it out without removing the radiator. I must be missing something, right? (I hope.)

It looks like this would be a simple job if I could get access to the front of the fan. Is it just bolted to the four studs that stick out from the clutch? If so, it would be easy if I could just get to those nuts, but the fan shroud prevents that.

My understanding is that the fan clutch nut has left-hand threads. Right? (I’m hoping that I get this far.)

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I just can’t imagine that Ram built this truck so that I have to remove the radiator to change the fan clutch. Some of you must have done this job before. I would really appreciate some pointers.

Thanks.

– Loren

 

[Loren]

I should have posted more information about the symptoms. Sorry.

I was towing our heavy RV home through slow traffic in Chicago last weekend and temperatures were reading high. Coolant temperature got to 225 degrees and the transmission temperature approached 185-190 degrees. The air conditioning was on the entire trip. The fan never engaged at any time during the 400 mile trip home.

The last mile of the trip includes a climb up a short, but steep hill for about half a mile. With a trailer in tow the coolant temperature usually reaches 200-210 degrees and the fan always engages by the time we reach the top of that hill. This trip it didn’t and the temperatures were higher than normal, about 225 degrees.

Based on the fan clutch failure rates I’ve seen mentioned on the forums I strongly suspect the fan clutch.

-- Loren

 

[Ltngdrvr]

Fan clutch is not really a common problem at all.

CEL on?
Codes?
If the clutch really wasn't engaging at all, it would get lots hotter than 225.
What shape is the shroud in? Mine deteriorated badly, letting air bypass the radiator.

 

[Loren]

Thanks for the reply ltngdrvr.

No CEL.

I don’t know about the codes. I don’t have a reader. Is there a way to get them other than with a reader?

The fan was turning as it normally does, it just didn’t “lock on” like it’s supposed to when the coolant gets hot.

The shroud is in great shape. I can’t see anything wrong with it at all. I’m pretty sure that the problem is not a lack of air flow through the radiator (dirty or bypassing) because the engine got hot and I didn’t hear the fan engage. If it were a cooling problem the fan would still engage but the engine wouldn’t get cool.

-- Loren

 

[gsbrockman]

The fan clutch has a verrrrry noticeable engagement right at 217°F ......at least on my last three CTD’s. If it was heat soaked......226°F isn’t unrealistic. I’ve hit 226°F a few times on long grades.

 

[NIsaacs]

My understanding is that the fan clutch nut has left-hand threads. Right? (I’m hoping that I get this far.)

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– Loren

I think it has right hand thread, but to be sure, take a close look at the nut.

 

[Loren]

The fan clutch has a verrrrry noticeable engagement right at 217°F ......at least on my last three CTD’s. If it was heat soaked......226°F isn’t unrealistic. I’ve hit 226°F a few times on long grades.

I agree 100%. The first time I heard it I thought my truck was going to self-destruct. The fan on my truck is not engaging.

-- Loren

 

[Loren]

I think it has right hand thread, but to be sure, take a close look at the nut.

View attachment 129081

NIsaacs,

Thanks. The acetylene regulator for my torch has those groves in the nut, but I've seen many other nuts with left-hand threads that do not have the groves. Those are very frustrating when trying to loosen the nut.

-- Loren

 

[Ltngdrvr]

I bet there are some youtube videos on how to R&R the clutch.
I would also check the wire harness and it's connections before blowing the money on a new one.
But, it really should be posting a code if the clutch isn't engaging when it's supposed to, and that would turn the CEL on.
Now, there may be pending codes, and yes, the only way to see them is with some sort of scan tool, but a basic one or one the parts store uses to check codes for you won't see pending codes.
I'd advise finding a good independent shop to do a proper diagnosis.

 

[Loren]

I bet there are some youtube videos on how to R&R the clutch.
I would also check the wire harness and it's connections before blowing the money on a new one.
But, it really should be posting a code if the clutch isn't engaging when it's supposed to, and that would turn the CEL on.
Now, there may be pending codes, and yes, the only way to see them is with some sort of scan tool, but a basic one or one the parts store uses to check codes for you won't see pending codes.
I'd advise finding a good independent shop to do a proper diagnosis.

Ltngdrvr,

That advice to find a good shop for a proper diagnosis is well taken. I was hoping to get this fixed by Tuesday (today is Sunday) for a trailer trip on Wednesday. I doubt that I can get a shop to check it out plus get the part and install it by time to leave. I guess I have to decide whether to run hot on the trip or cancel it.

I did check out as much of the wiring as I could find. I also cleaned and reconnected the connector from the wiring harness to the fan clutch. I haven't gotten the truck hot yet to see if that was the problem, but I didn't see anything wrong when I checked everything.

I'll have to stop at the library (free Wi-Fi) tomorrow and see what I can find on YouTube. I had thought of that option but we don't have unlimited data out here in the sticks. I can't download a bunch of videos here, so I'll try the library tomorrow.

Thanks for the ideas.

-- Loren

 

[Ltngdrvr]

Well, if 225 was as hot as it got then it is still a ways from over-heating, I've had mine quite a bit hotter than that.
But, probably best to err on the side of caution.

Just don't take it to the dealer, most expensive place and many times the least knowledgeable.

 

[Loren]

Well, if 225 was as hot as it got then it is still a ways from over-heating, I've had mine quite a bit hotter than that.
But, probably best to err on the side of caution.

Just don't take it to the dealer, most expensive place and many times the least knowledgeable.

That’s good to hear. It tells me that I’ll probably be alright if I take the trailer trip as planned.

I’ll still do some research at the library to see what’s on YouTube, but I feel better about the situation now.

Thanks for the help.

– Loren

 

[AH64ID]

It’s not uncommon for fans to set under speed codes and not trip a CEL. They are called soft codes. Swing by an auto parts store and use their scanner to see if one set. If you do replace the fan clutch I’d stick to OEM since the aftermarket ones don’t get the best reviews.

225° is the max allowable temp Cummins publishes for use with the 190° thermostat. Temps above that indicate that the heat rejection of the cooling system isn’t up to par. I know Ram says 245° is overheating, but I think Cummins knows their stuff better. 207° is full open on the thermostat and at 215-217° the fan rpms should be running 2500-3000 rpms, which is LOUD.

 

[Topzide]

@Loren, For reading codes, I'd suggest getting the AlfaOBD software and a MX+ Bluetooth OBD tool. Both will set you back about$125-150. Software only runs on Android or Windows. Sorry no IOS at this point. This allows reading codes and being able to check lights on truck and trailer be yourself! Allows many other adjustments and changes. You can pull pin code and program key FOB's instead of going to dealer! JM2C. Plenty of help with AlfaOBD here and other places. Good luck!

 

[Loren]

AH64ID,

I’m with you. The fact that I couldn’t hear the fan with the coolant at 225 degrees was a clue. I may not get to an auto parts store before our trip, but I’ll do it before I invest several hundred dollars in a fan clutch that may not be needed. As much as I believe that the problem is the clutch itself, it would be foolish not to check for codes.

Thanks.

– Loren

 

[Loren]

Topzide,

I’ve heard of the AlfaOBD but I don’t think I’d use one enough to justify the expense. I think I’ll try an auto parts store first to see if they can find any codes.

Until now I’ve never needed what an AlfaOBD offers.

Thanks for the suggestion though.

– Loren

 

[Tuesdak]

Fan clutches are a wear item. They fade away over time loosing like 200 RPM per year. Further they become slower to respond to speed up requests from the ECM. Simply put at 5 years old it's not a waste of money to replace them. All the CEL's diags, etc. are simply for a DROPPED DEAD fan clutch and warranty avoidance otherwise. Locked up fan clutch, missing wires, leaked out, won't lock up at all may set a code. Sort of works after 15 min of trying was the last diag I read... Stuff that barley or sort of works gets a free first pass for some reason. When you look deeper yeah it may be time.

This doesn't mean you throw parts at something. Simply saying it's a wear item that is difficult to understand the wear out conditions.

 

[Elsbury]

My fan clutch on my 19 would not disengage...no codes so the first tech said nothing wrong with it. I went to another dealer sounding like a jumbo jet taking off. They diagnosed and fixed it no problem. I guess it doesn't always send a code if bad?

 

[Loren]

Thanks, guys, for all the input.

I did two things today. First, I went to the library and found several YouTube videos on removing the fan clutch. It looks like I can either unscrew it and work it out around the shroud or unscrew it and unbolt the shroud and take the shroud, the fan, and the fan clutch out as a unit. I’ll try one of these methods when I change the clutch. That will probably happen next week sometime.

It also looks like the fan clutch threads are right-hand. I'll verify this later.

The second thing I did was to get the guys at Advance Auto Parts to check my truck for codes with their scanner. NO CODES. I guess that means that the problem is in the clutch itself rather than some temperature sensor somewhere. I consider that to be a good thing because I can change the fan clutch myself.

Aside: Advance Auto Parts offers a discount to active-duty, retired, reserve, and some other categories of veterans. See here:
https://www.militaryveterandiscounts.com/advance-auto-parts-military-discount/

Thanks again to all who helped. I’ll post the results after I’ve changed the fan clutch, although it may take some time before the truck gets hot again. Unless I’m towing something heavy it never heats up.

– Loren

 

[Ltngdrvr]

I can tell you the fan unbolts from the clutch fairly easily once you get the shroud out of the way.
I believe the nuts on it are 10mm.
Small hands may be able to work in with the shroud on to get the fan loose.