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Old 11-18-2018, 10:42 PM   #1
Mini-Skoolie
 
Join Date: Sep 2018
Location: TX
Posts: 29
Year: 2000
Coachwork: Bluebird
Chassis: TC2000 FE
Engine: 5.9l Cummins ISB
5.9 Fan Cycles Constantly

Hi All,
I'm fairly new to this forum, and I just picked up my new (to me) bus Friday in Colorado, and am on my way home to Texas in it now. It's a 2000 Bluebird TC FE with a 5.9 Cummins. It has the single gauge that you have to cycle through between fuel, temp, battery, and oil pressure. I also have a separate trans temp gauge.

First day out, I only went about 200 miles. The engine temp gauge stayed around the mid-point, well out of the red even when climbing and sitting in traffic. The trans temp (if I can trust any of these gauges) never showed more than about 140. It was around 35 degrees outside. However, I noticed my fan would come on regularly.

I started counting how much the fan cycles today. The air temperature was around 34 degrees today. The fan only comes on on the highway, above around 50 mph. The temp gauge actually climbs just slightly when the fan comes on, and returns to the middle when the fan shuts off. The fan cycles roughly every 30 seconds! On for 30, off for 30, and repeat. There is no indication that I can tell that the engine is actually getting hot. I don't feel any heat coming off the doghouse, and I even raised it once while driving and didn't notice any excessive heat (but yeah, it's loud!!). I drove 350 miles today with the fan doing this the entire time. The bus runs around 2300 rpm at 60mph (the plate says it has 4.44 gearing).

Ideas? Suggestions? Should I swap the fan clutch? Temp sensor? I have another 250 miles to go tomorrow. At this point, other than the fan coming on constantly, everything else seems to be fine, so I'm planning to just drive home then figure it out, but would welcome some insights or suggestions on what is happening.

Thanks!

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Old 11-19-2018, 09:16 AM   #2
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For your next drive turn on all the heaters and see what the reaction is.
You may need to flush the rad and replace the antifreeze. but, get the antifreeze tested first. If it is mostly water then it cannot do the cooling thing properly.
Are you sure your cooling system is full with no air? Rad cap condition, tight?



Just some early thoughts looking at simple things first.


John
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Old 11-19-2018, 11:28 AM   #3
Mini-Skoolie
 
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Year: 2003
Coachwork: Ford E450, Collins 20 Passenger
Engine: Ford 7.3L Powerstroke
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My '93 Cummins 5.9 had a fan running at all times due to a failing fan clutch. I would imagine yours would be running consistently if it was the same problem, however, I'm not the most qualified to answer this.
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Old 11-19-2018, 11:40 AM   #4
Skoolie
 
Join Date: Jan 2015
Posts: 242
Have you checked the coolant level since cycling thing has started?

i liked blackjohns idea of turning on the heater fans.
Just make sure that if your bus has valves under the hood on the coolant hoses that are all open.

The bus i drive has 3 large heaters and (6) 2 speed fans all together.
The heaters together are about the same size as the radiator. It takes me an hour of driving to get my bus to 180 in the mornings. That is how much those heaters work.
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Old 11-19-2018, 09:06 PM   #5
Mini-Skoolie
 
Join Date: Sep 2018
Location: TX
Posts: 29
Year: 2000
Coachwork: Bluebird
Chassis: TC2000 FE
Engine: 5.9l Cummins ISB
Quote:
Originally Posted by BlackJohn View Post
For your next drive turn on all the heaters and see what the reaction is.
You may need to flush the rad and replace the antifreeze. but, get the antifreeze tested first. If it is mostly water then it cannot do the cooling thing properly.
Are you sure your cooling system is full with no air? Rad cap condition, tight?



Just some early thoughts looking at simple things first.


John
Thanks John. Looking at simple things first is a good start, since I'm new to this. The bus made it home today, with the fan still cycling on the highway, but below about 45mph it quit doing that. It will be a week or so before I have time to get back to it, but I will definitely start with a full flush and bleed. The bus sat for most of the last year of its' service life, so I'm going to change all the fluids as a precautionary service.
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Old 11-19-2018, 09:09 PM   #6
Mini-Skoolie
 
Join Date: Sep 2018
Location: TX
Posts: 29
Year: 2000
Coachwork: Bluebird
Chassis: TC2000 FE
Engine: 5.9l Cummins ISB
Quote:
Originally Posted by Mekanic View Post
Have you checked the coolant level since cycling thing has started?

i liked blackjohns idea of turning on the heater fans.
Just make sure that if your bus has valves under the hood on the coolant hoses that are all open.

The bus i drive has 3 large heaters and (6) 2 speed fans all together.
The heaters together are about the same size as the radiator. It takes me an hour of driving to get my bus to 180 in the mornings. That is how much those heaters work.
The level was low when I checked it yesterday morning, and I topped it up, but the fan continued to run. I did open both valves for the heaters and ran them a bit. I got some warm air out of the rear one, but mostly just fan air out of the front one. And never got the driver foot heater to work at all. First project next week is a full system flush and then I'll try to sort out the heater situation. My electrical switch panel next to the driver has some issues both from age, and from the school district removing some of their equipment before auction, so I have some tidying up to do with the electrical system as well.
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Old 11-19-2018, 09:36 PM   #7
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Join Date: Jul 2017
Location: Huntington Beach CA.
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Year: 1991
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Chassis: T/C 2000 28 foot Handy Bus
Engine: Cummins 5.9 Mechanical
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Quote:
Originally Posted by 2RideTheGlobe View Post
The level was low when I checked it yesterday morning, and I topped it up, but the fan continued to run. I did open both valves for the heaters and ran them a bit. I got some warm air out of the rear one, but mostly just fan air out of the front one. And never got the driver foot heater to work at all. First project next week is a full system flush and then I'll try to sort out the heater situation. My electrical switch panel next to the driver has some issues both from age, and from the school district removing some of their equipment before auction, so I have some tidying up to do with the electrical system as well.
Hi I have a tc2000 1991 and the 5.9 also. There is a tube and a valve on mine above the radiator and a detailed produre to fill and top off the system. you have to fill it and bleed it a couple of times.
If you look online you can find a copy of the drivers guide and it should be in there.
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Old 11-20-2018, 02:23 AM   #8
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I have the T444e in mine and a 5-speed manual trans behind it. At lower engine speeds, my fan rarely engages but at full throttle on the highway (top speed 55 with 5.38 rear-gears) mine also cycles every 30 seconds or so. Temp stays in the 180-190 range. As long as it's not overheating (or staying under 180-ish) I wouldn't consider it abnormal.


All that said, it would be wise to check everything, service the cooling system and fan clutch and all that.
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Old 11-20-2018, 08:29 AM   #9
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Quote:
Originally Posted by Rivetboy View Post
Hi I have a tc2000 1991 and the 5.9 also. There is a tube and a valve on mine above the radiator and a detailed produre to fill and top off the system. you have to fill it and bleed it a couple of times.
If you look online you can find a copy of the drivers guide and it should be in there.
Hope this helps.

If you are going to change fluid, bring lot$. Our TC1000 holds about 25 gallons.
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Old 11-22-2018, 01:06 PM   #10
Mini-Skoolie
 
Join Date: Sep 2018
Location: TX
Posts: 29
Year: 2000
Coachwork: Bluebird
Chassis: TC2000 FE
Engine: 5.9l Cummins ISB
Thanks Don, and RivetBoy, for your info. My bus has a plastic "surge tank" on top of the radiator, and the cap is attached to the tank. The instructions say to fill it up to the bottom of the fill neck and then run it until warm and add as necessary. I'll have to look again; I didn't see a valve at the top of the rad or the tank, but there may be one.
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Old 11-22-2018, 01:52 PM   #11
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Chassis: T/C 2000 28 foot Handy Bus
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Rated Cap: 2
Quote:
Originally Posted by 2RideTheGlobe View Post
Thanks Don, and RivetBoy, for your info. My bus has a plastic "surge tank" on top of the radiator, and the cap is attached to the tank. The instructions say to fill it up to the bottom of the fill neck and then run it until warm and add as necessary. I'll have to look again; I didn't see a valve at the top of the rad or the tank, but there may be one.
N mine is a quarter inch black plastic line that comes from the transmission heat exchange your underneath and comes up to a brass valve on the end of that piece of tubing that's kind of flopping around on top of the radiator
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Old 11-29-2018, 01:54 AM   #12
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If all of the hot water valves are open and you are not getting any heat out some of the heaters and only warm air out the others then I would say your system is full of air.

Each heater core has a bleeder screw somewhere in the side of the core. If you don't bleed the air out the water will never circulate. If the water doesn't circulate you will never get hot water running through the heater cores.

It is possible that your fan is cycling because it recognizes things are hot. But since the water isn't really circulating it will cool off that same section of coolant multiple times because that one spot of coolant is getting hot and cooled back off. If you open the system up to the rest of the 20-some gallons of coolant I doubt the fan will need to cycle and stay off.

At the ambient temps you are experiencing the fan clutch should not be engaging. Ever! The action of driving through the air should keep things cool enough that you might be wishing you had either shutters or a weather front to prevent over cooling.

Your handiest tool for diagnosing issues like this one an electronic laser thermometer is a great tool to have.
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Old 11-29-2018, 07:50 AM   #13
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Question is it a clutch fan or air operated fan ??
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Old 11-29-2018, 08:10 AM   #14
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Quote:
Originally Posted by 2RideTheGlobe View Post
Thanks Don, and RivetBoy, for your info. My bus has a plastic "surge tank" on top of the radiator, and the cap is attached to the tank. The instructions say to fill it up to the bottom of the fill neck and then run it until warm and add as necessary. I'll have to look again; I didn't see a valve at the top of the rad or the tank, but there may be one.
It's there, tucked into the keepers for the ws washer hose.
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Old 12-23-2018, 10:13 AM   #15
Mini-Skoolie
 
Join Date: Sep 2018
Location: TX
Posts: 29
Year: 2000
Coachwork: Bluebird
Chassis: TC2000 FE
Engine: 5.9l Cummins ISB
Quote:
Originally Posted by cowlitzcoach View Post
If all of the hot water valves are open and you are not getting any heat out some of the heaters and only warm air out the others then I would say your system is full of air.

Each heater core has a bleeder screw somewhere in the side of the core. If you don't bleed the air out the water will never circulate. If the water doesn't circulate you will never get hot water running through the heater cores.

It is possible that your fan is cycling because it recognizes things are hot. But since the water isn't really circulating it will cool off that same section of coolant multiple times because that one spot of coolant is getting hot and cooled back off. If you open the system up to the rest of the 20-some gallons of coolant I doubt the fan will need to cycle and stay off.

At the ambient temps you are experiencing the fan clutch should not be engaging. Ever! The action of driving through the air should keep things cool enough that you might be wishing you had either shutters or a weather front to prevent over cooling.

Your handiest tool for diagnosing issues like this one an electronic laser thermometer is a great tool to have.
I'm really slow in following up on these. Thanks for the suggestions. I had a local shop flush my cooling system last week, and the fan is still coming on, though it's not as regular as it was. Sometimes it runs for quite a while now, and sometimes it stays off for a few minutes at a time. It comes on the first time after about 5 minutes of driving. It's never come on while sitting idling in traffic, but it has come on at as low as 30mph now, whereas before it never came on below about 45-50mph.

I hadn't thought to use my infrared thermometer. Will do that in the next day or two, and check several different locations.

I have to admit, I'm less than impressed with the performance of the local shop I used. Several things weren't done right, and then they told me they don't have anyone there with a license to drive my bus (and they work on 18-wheelers?). So apparently nothing there gets road-tested or evaluated. Back to doing it myself.
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