Cummins ISB 340 Engine Overheating Overheat Fan Clutch Thermostat Cooling etc.

[BOTEWCC]

Hi, I just registered to the site due to the same overheating issues this entire thread is about. I have 2008 Fleetwood Expedition with about 47K miles. i guess I should consider myself lucky that I didn't have the problem before.

Is the only disadvantage of having the radiator fan running all the time is a potential drop in gas mileage? I'm considering ways to handle this whole overheating and fan clutch issue and I think i have 3 options:
1. replace the fan clutch with a new one, $1500+
2. get ride of the fan clutch entirely with a direct drive fan blade from Source Engineering, probably around $1300+
3. Take out the 5A fuse that controls the fan clutch, $0 (I may have to worry about the four bolts holding on the fan clutch loosening or shearing off, I guess)

Am I missing something? Does anyone have more thoughts on this matter to help enlighten me?

Thanks for any help!

[f14av8r]

Originally Posted by BOTEWCC

Hi, I just registered to the site due to the same overheating issues this entire thread is about. I have 2008 Fleetwood Expedition with about 47K miles. i guess I should consider myself lucky that I didn't have the problem before.

Is the only disadvantage of having the radiator fan running all the time is a potential drop in gas mileage? I'm considering ways to handle this whole overheating and fan clutch issue and I think i have 3 options:
1. replace the fan clutch with a new one, $1500+
2. get ride of the fan clutch entirely with a direct drive fan blade from Source Engineering, probably around $1300+
3. Take out the 5A fuse that controls the fan clutch, $0 (I may have to worry about the four bolts holding on the fan clutch loosening or shearing off, I guess)

Am I missing something? Does anyone have more thoughts on this matter to help enlighten me?

Thanks for any help!

I see where some have wired a switch to the fuse so they can turn it on and off at will. That might be the best solution. I'd be wary of allowing the fan to run continuously for a number of reasons.

I had my fan clutch replaced and it never gave me a problem for the next 40K miles that I owned the coach. If you plan to keep your coach for a long time, I'd go that route.

[fagnaml]

Botewcc --

Welcome to the forum! There are many good members who are willing to help anytime!

For your overheating issue, when was the last time that you cleaned your charge air cooler (CAC) and the outside of your radiator? A dirty CAC would cause overheating regardless of fan speed as a dirty CAC restricts air flow through the CAC and radiator.

When was the last time you had your coolant changed, radiator flushed and thermostat replaced? A bad or "sticky" thermostat can caused overheating by not opening properly.

Just a couple of zero / low cost thoughts before spending big money on fan clutch replacement or finding ways to keep the fan in high speed at all times.

[Britcanuck]

Originally Posted by BOTEWCC

Hi, I just registered to the site due to the same overheating issues this entire thread is about. I have 2008 Fleetwood Expedition with about 47K miles. i guess I should consider myself lucky that I didn't have the problem before.

Is the only disadvantage of having the radiator fan running all the time is a potential drop in gas mileage? I'm considering ways to handle this whole overheating and fan clutch issue and I think i have 3 options:
1. replace the fan clutch with a new one, $1500+
2. get ride of the fan clutch entirely with a direct drive fan blade from Source Engineering, probably around $1300+
3. Take out the 5A fuse that controls the fan clutch, $0 (I may have to worry about the four bolts holding on the fan clutch loosening or shearing off, I guess)

Am I missing something? Does anyone have more thoughts on this matter to help enlighten me?

Thanks for any help!

Your #1 option is the one that I would recommend. Your engine is of the vintage when the fans installed were problematic. Mine is a 2010 and a new fan fixed the problem. A friend has a 2008 Itasca and a new fan fixed same problem. In the long run it’s the best option

[scooterbob]

is the fan clutch a Cummings product or aftermarket ?

[BOTEWCC]

So, its now 12/2019, can you give us an update about your direct drive fan blade from Source Engineering and any issues you may have had since you had it installed?

One question I have: Does your engine warm up very slowly in cold weather since the fan never stops pushing air through the radiator? Have you noticed any gas mileage decrease since running this system?

Thanks!

[BOTEWCC]

So you're suggesting just replacing the OEM fan clutch with a new OEM fan clutch? How long and how many miles have you had your replacement fan clutch now? Do you have any information that indicates the Horton (the fan clutch manufacturer) has made improvements to their original design?

[BOTEWCC]

Yes, I power washed out the CAC and radiator and still had the issue. Then, I replaced the thermostat, engine coolant sensor and changed the radiator coolant. The overheating issue is intermittent and usually occurs soon (within 10 minutes) after starting up first thing in the morning. After a couple stops on the side of the road it seems to work ok for the rest of the day...

[scooterbob]

After a couple stops on the side of the road it seems to work ok for the rest of the day...[/QUOTE]

That is exactly how mine was acting after I pulled over to the side of the road one or two times and it was start running normal. I did rig up a switch to the 5 amp fuse for emergency

[Britcanuck]

If you have a relationship with a service dealer who is authorized for Freightliner they should be able to pull up Technical Service Bulletin 3737. If they run your VIN it will tell if the TSB applies to your chassis. This is not a recall (it should be) just a technical bulletin.

It's your choice of what remedial action you want to take. The shop that I use idicated that they had seen a number of leaking fan clutches.I thought about a solid drive fan but didn't like the idea of what it would do to fuel consumption. My new fan has been on for 4-5 years now. Probably about 25,000 miles

[Britcanuck]

It's a Horton product

[scooterbob]

I would like to no what controls the fan clutch ? Relay/thermos/ or what ?
The reason I ask is it only happens when first startup when engine is cold, after a pull over and shut down 1 or 2 times, it works fine 192* and it doesn't do it every day I start up.
It is my thinking that if it was the fan clutch it would do it all the time..

[ziaptrn]

As best I can tell after lots of research - next is call to Horton....
1. The Cummins engine sends either "on" or "off" to the fan for operation. The engine itself achieves a set temp and then triggers the fan.
2. The fan clutch on our rigs is controlled electronically via "Pulse Width Modulation" which is managed by the harness that runs from the engine to the fan clutch. The harness speeds up/slows down the fan (supposedly) as needed. I wonder now if the harness is the true culprit?



I also installed a switch that disconnects the 5amp fuse (or reconnects depending on position) and mounted the switch in the dash. What I can tell you is that the switch does work, but it takes a little time i.e. it isn't instantaneous while the engine is running. It is easy to see when it does engage if you watch temps and transmission temp especially. I was surprised at the length of time required, but found that if I wait maybe 60-90s, the fan will lock and engage and the reverse when the switch is put back in 'normal'.


Like you, the issue is also resolved by pulling over to the side of the road, turning off the engine, counting to 4, and then re-starting. This works every time and is immediate.


The other odd thing is that the error is not reliably reproduced. Furthermore, it seems to be worse in cold weather versus warm i.e. doesn't happen when the ambient temps are in the 60-70 degree range to start, but when it is cold out, it requires intervention more reliably.


No one can find anything wrong with the engine or fan clutch - new radiator, cleaned precooler, new thermostat, new radiator cap, installed 'Guard Dog' (made by Horton for this specific fan clutch)



For some reason all shops insist on having it happen while in the shop and won't believe the photographs that I show (over-temp light, transmission in 200s, engine in 200s followed by resumption of normal temps after flip the switch or re-start). No one has "ever heard of such a problem) at Cummins, Freightliner (including Gaffney), or Winnebago.


Just to validate your experiences if nothing else....

[scooterbob]

Ziaptrn
Thankyou for all the information.