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Engine Fan Clutch


alan0043

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Hi Everyone,

 

I have been doing some work on my truck. It is now time to look at the clutch on the fan for the engine. I have a feeling that the clutch on the fan is stuck on. When the truck is parked and the engine is off, I have tried to turn the fan by hand with no luck. The fan seems to be running all the time. What kind of test do I need to do to the truck to see if the clutch on the fan is stuck on ? Someone suggested that I supply compressed air to the clutch on the fan. How do I do this ? Do I make an adaptor to go from the air compressor to the clutch ? How many pounds of air do I need ? Is there anything that I am missing ? Is this the right test to do ? Or is there something else that I need to do ?The truck engine is a Cummins N14.

 

Thank you for all help,

Al

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Al,

 

My fan does not freewheel when the truck engine is turned off and cannot be turned by hand. When first started the fan will be engaged until air pressure is built up and the truck 'determines" it is not overheating and the solenoid sends air to the clutch and the fan disengages. I assume it is tied to the thermostat so when the temp rises the fan re engages. Start the truck and watch the fan until air pressure is built up and you will probably see the fan disengage and spin slowly. At this point, I took a single sheet of rolled up paper and could spin the fan easily forward and backward. DO NOT stick your hand in to spin it. If it spins freely, your clutch is not locked up. Here is the thread that several helped me with on this issue. I would bet yours functions like mine even though I have the Volvo D12 with a Horton fan clutch.

http://www.rvnetwork.com/index.php?showtopic=120413

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Al like Suite says the fan is engaged when the engine is off. You can't turn it. I had the same problem. I have the Volvo engine so yours is probably different but mine has an air line on the passenger side of the engine and there was a connection that I unhooked and applied air to the clutch. You will see it move when you hit it with air. If it does not move tap it gently with a mallet while someone else keeps air on it.

I have personal experience with this. My clutch was stuck and ran all the time. I had another problem and when it was in the shop they broke the clutch loose and replaced the solenoid that controls it. Shortly after and in another part of the country it stuck again and since it had a new solenoid in it that could not possibly be the problem and they changed the clutch. Things were fine for a while but it stuck again and in another part of the country. By now I had learned enough about what was what and I knew there were a couple of unused solenoids under the truck since they controlled things that I no longer had. So I pulled the "new" clutch solenoid and took it apart. It was rusty inside and stuck. Who knows if I really needed a new clutch. The extra solenoids did not work reliably when I swapped one into the clutch position so I bought a new one and replaced it 2 years ago. No problem since.

 

Don't let them replaced a clutch until you have ruled out a $100 solenoid.

 

Brad

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Al like Suite says the fan is engaged when the engine is off. You can't turn it. I had the same problem. I have the Volvo engine so yours is probably different but mine has an air line on the passenger side of the engine and there was a connection that I unhooked and applied air to the clutch. You will see it move when you hit it with air. If it does not move tap it gently with a mallet while someone else keeps air on it.

I have personal experience with this. My clutch was stuck and ran all the time. I had another problem and when it was in the shop they broke the clutch loose and replaced the solenoid that controls it. Shortly after and in another part of the country it stuck again and since it had a new solenoid in it that could not possibly be the problem and they changed the clutch. Things were fine for a while but it stuck again and in another part of the country. By now I had learned enough about what was what and I knew there were a couple of unused solenoids under the truck since they controlled things that I no longer had. So I pulled the "new" clutch solenoid and took it apart. It was rusty inside and stuck. Who knows if I really needed a new clutch. The extra solenoids did not work reliably when I swapped one into the clutch position so I bought a new one and replaced it 2 years ago. No problem since.

 

Don't let them replaced a clutch until you have ruled out a $100 solenoid.

 

Brad

 

Brad,

 

What psi of air pressure did you use for the clutch for your test ?

 

Al

 

 

 

Carl,

 

The speed of the fan does not change and any time. No matter how long the engine runs.

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Brad,

 

What psi of air pressure did you use for the clutch for your test ?

 

Al

 

 

 

Carl,

 

The speed of the fan does not change and any time. No matter how long the engine runs.

Not Brad but at least 100psi. Truck while running maintains air pressure between 100 - 125 psi so suspect solenoid likes to see at least 100. Also take a single sheet of paper as I did above and after truck had built up pressure above 100 ease it toward the fan blade. If the fan does not stop spinning easily then in all likelihood clutch is staying engaged either from a bad solenoid or a bad clutch. As Brad said if you can get independent air to the line supplying the fan clutch and then fan free wheels when air is supplied, then probably means the clutch is ok and it is the solenoid. You don't need the truck running if you can get independent air. Also as mentioned in the linked thread the fan clutch is tied in to the thermostat so that could also be a point of failure. I don't know how to check that.

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Al I agree with Carl that it should be about 100 Lbs. However, in all honesty I don't know what pressure I used. I just unhooked the line and hit it with my CO2 bottle for the tires. I Have no idea on your engine but my solenoids are in a bank under the truck and the fan clutch line is green. Please keep us informed. I'm real curious about this.

 

Brad

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I have no idea about simularities between the '98 with a Cummins and my '01 with a Detroit so this might not work for all. My '01 has air to the fan. My brother is a truck driver and been one for 35 years. Always drove Freightliner with a Detroit. I thought my fan clutch was broke because it would not spin when shut off air pressure or not. While at his house, he showed me that it will spin if the ignition is turned on. Sure enough, it spun when I turned on the ignition w/o starting the engine. Don't think it needed air but not sure if air was built up when I tested it.

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Guest THE TRAILERKING

I believe the default the clutch is engaged and released by air action.

Yes usually should be spring engaged. That way in the event of an electrical problem or air supply issue to the fan hub....You still have an operational fan for cooling.

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TRAILERKING,

 

Thank you for the links. They are going to be helpful. I have the links saved.

 

Al

 

Al I agree with Carl that it should be about 100 Lbs. However, in all honesty I don't know what pressure I used. I just unhooked the line and hit it with my CO2 bottle for the tires. I Have no idea on your engine but my solenoids are in a bank under the truck and the fan clutch line is green. Please keep us informed. I'm real curious about this.

 

Brad

 

Brad,

 

The solenoid for the fan is mounted on top of the fan clutch assembly with a short 4" to 5" long black tubing going from the solenoid to the clutch assembly. The air line that goes to the solenoid is also 1/4" dia. black tubing coming from the rear of the engine compartment. I have made an adaptor to go to the clutch assembly to a quick release air chuck. I will set the air compressor to 110 psi. I will do this test later day. I will report back tomorrow on what I find. If anything that is wrong, I am hoping it is the solenoid. It does not look to bad to replace. There is 2 wires coming off of the solenoid. If it is the fan clutch, it is going to be a big job!

 

Keep the ideas coming,

Al

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Al

That is the end of my ideas. Just remember that even if applying air does not make it move it is possible that if the solenoid is bad AND it has long enough to let the clutch stick you may have to have help so someone can apply air pressure at the same time that you can tap on the clutch housing with a mallet to break it loose. Just throwing that possibility out for you. Good luck. Keep us posted.

 

Brad

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Al

That is the end of my ideas. Just remember that even if applying air does not make it move it is possible that if the solenoid is bad AND it has long enough to let the clutch stick you may have to have help so someone can apply air pressure at the same time that you can tap on the clutch housing with a mallet to break it loose. Just throwing that possibility out for you. Good luck. Keep us posted.

 

Brad

Apply air both before and after the solenoid will confirm weather the solenoid is the problem or not. You can test the solenoid also by supplying 12V from an external source.

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Al

That is the end of my ideas. Just remember that even if applying air does not make it move it is possible that if the solenoid is bad AND it has long enough to let the clutch stick you may have to have help so someone can apply air pressure at the same time that you can tap on the clutch housing with a mallet to break it loose. Just throwing that possibility out for you. Good luck. Keep us posted.

 

Brad

 

Hi Everyone,

 

I did the air test yesterday. The truck failed the test. After putting air to the fan clutch and using a mallet to tap on the clutch. The fan still does not move. One thing that I did find was the fitting on the clutch is leaking air. The only way to fix this fitting is to remove the fan clutch. I used a new piece of 1/4" tubing with fresh cut ends and there is still an air leak. This is one reason for removing the clutch being that there is no way to move the fitting. Once the fan clutch is removed I can replace this air fitting.

 

It looks right now I would have to remove the radiator and fan shroud. Is there any other way around this. Right now I can't think of a way. While there is one way. Write out a check and have someone else do the work. Option # 2 is not on the books.

 

Looking for help to remove the fan clutch,

Al

 

Is there anyone out there that has done this repair ?

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Alan, on my '95 WHite Volvo, the clutch is stuck from not enough use. It worked last year, now its rusted together. I used a rubber tipped air nozzle on the engage hose to test if it released or engaged at all. I need to whack it a few times!!

I had the clutch off my other similar truck cause it wasn't engaging. The job was easy and simple. I released the belt tension, then reached in with a ratcheting straight wrench and removed the bolts from the fan and gently laid it forward against the radiator. Mine had room to do this. Unhooked the hose. Then I removed the 4 bolts holding the fan clutch and bearing assm to the N14 motor (actually the bearing assm. was slotted for the bolts, simply loosening the last two allowed it to slide off) and the unit simply came right out. 15 minutes. Reinstall was almost as simple,

 

Unfortunately other trucks may not have as much room, or be a simple. But then I've done a lot of things that they said couldn't be done that way....

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Al,

When my clutch was replaced the rad and shroud had to come off. Sorry. And being a full timer I don't have nearly enough tools or nerve to tackle that project.

 

Brad

I also operate under the principle that if I take the truck to the shop before I break something when I should never have attempted it in the first place it is easier to drive it to the shop than to have it towed. That is no fun trust me on that one.

 

Brad

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When my fan clutch was frozen, I had someone free it by numerous strokes of a hammer and the application of some fluid.

 

The clutch was free for a while. Then the clutch lining started to crumble. That is when the reality check of having the clutch rebuild versus a radiator, heat exchanger, hood, etc was brought to my attention in a regular servicing.

 

Anew clutch is very expensive. The rebuild kit is far more economical. Most of the cost of the repair is the access, all the stuff in front of the fan.

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Alan

Do you have a M11?

If so you can remove the clutch after unbolt inc fan.

I have done it!

Is the air leak at the fitting or a white plug facing the motor?

 

Roger

 

Roger,

 

The engine is a N14. I do not see a white plug. The fitting is pointing to the drivers side of the truck. You can put your hand close to the fitting an feel the air.

 

Al

 

 

Hi Everyone,

 

Thank you for your help. I looked at the truck and it might be possible to remove the fan shroud with out taking the radiator out. There is some tubing that will have to come of the engine. The tubing that I am talking about is for the intercooler. The top hose from the radiator tank will need to come off. It also looks like I will need some new wrenches to help with the job. I will need some racketing wrenches. One other nice thing is that the truck is at home and I have 2 sons that can help me. If it takes me 4 days to do the work that is ok. I will also replace all the belts on the engine. To bad there is no manual out there telling you the steps that you need to do this job.

 

Please keep the help coming,

Al

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