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Author Topic: Fan clutch noise and how to quiet it down.  (Read 751 times)

Jack D

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  • Posts: 228
  • Elmira, OR
    • HMDS
Fan clutch noise and how to quiet it down.
« on: July 19, 2013, 12:00:33 PM »
My 1985 Itasca with the 454 Chev. has a fan clutch that sounds like a 747 taxiing for takeoff. It appears to be operating normally so I'm looking for ways to make it operate less (I think). We do not have an overheating issue. Our in-dash AC unit does not work and is not really needed, so would removing the condensor from in front of the radiator be an answer? Adding another electric fan? Are there other things I haven't thought of?
« Last Edit: July 19, 2013, 01:48:42 PM by Jack D »
Jack

23' '85 Itasca Sunflyer, followed closely by:
16' '73 Old Towne FG Canoe

halfwright

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  • Posts: 429
Re: Fan clutch noise and how to quiet it down.
« Reply #1 on: July 19, 2013, 08:22:01 PM »
There might be a fan available with fewer blades. The only place I can think of to ask would be the dealership or some old chevy mechanic.
Jim And Darlene Wright
Ryder, the Ethiopian monkeybeaver dog
2007 Montana Mountaineer
2002 F250 Super duty 7.3 liter

SeilerBird

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  • Posts: 4836
Re: Fan clutch noise and how to quiet it down.
« Reply #2 on: July 19, 2013, 08:53:41 PM »
Replace the fan. It is defective. I have had two motorhomes with 454s and the fan was much quieter than "a 747 taxiing for takeoff".

denmarc

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  • Posts: 1264
Re: Fan clutch noise and how to quiet it down.
« Reply #3 on: July 22, 2013, 11:46:51 AM »
Replace the fan. It is defective. I have had two motorhomes with 454s and the fan was much quieter than "a 747 taxiing for takeoff".

Just some notes...

It may be possible to replace only the fan clutch if that is the source of the noise.  They do go bad.  Back in those days, the clutch and fan blades were two separate pieces.  Check it out carefully.  It could be a clutch going bad.  Worse yet, it could be fractures in a blade or two.  Pieces that could come flying off at any minute!  May be something to check out. 

Another option may be that there used to be aftermarket fan blades available with more flexable blades available that were quieter at higher RPM's due to having blades that more flexable.  The blades would flatten more at the higher RPM's cutting and pushing less air, creating less noise.  As long as engine temp/overheating isn't an issue, maybe that would work for you.
Mark

1994 Jayco Eagle 370FB on 24 acres of paid off paradise in Michigan.

Fantasy is a necessary ingredient in living.  It's a way of looking at life through the wrong end of a telescope.

Dr. Seuss

Jack D

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  • Posts: 228
  • Elmira, OR
    • HMDS
Re: Fan clutch noise and how to quiet it down.
« Reply #4 on: July 22, 2013, 11:57:01 AM »
The noise is not a defective clutch. It comes from the fan blades beating the air. The blades are very agressive and create a loud roar when the clutch is fully engaged. I can live with it, if that's my only option. Since the in-dash air doesn't work anyway, I'm thinking that removing the condensor in front of the radiator would keep the fan clutch from engaging except in extreme conditions. Or perhaps adding another electric fan (it has one now).
Jack

23' '85 Itasca Sunflyer, followed closely by:
16' '73 Old Towne FG Canoe

dan2

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  • Posts: 169
  • 1988 Pace Arrow, P-30 GMC Upgrade, Banks, 03 F-150
Re: Fan clutch noise and how to quiet it down.
« Reply #5 on: July 22, 2013, 12:52:43 PM »
Do you have a sensor on the radiator itself? My P30 has two electric fan(s) if front of everything.... I hear them roar when I leave
A stop light, (when it's hot) but quit after a few seconds. Check the lower drivers side of radiator. I like to hear them  :) I know I'm
getting max cooling.
Good luck
Dan

Jack D

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  • Posts: 228
  • Elmira, OR
    • HMDS
Re: Fan clutch noise and how to quiet it down.
« Reply #6 on: July 22, 2013, 01:27:29 PM »
The electric is manual from a dash switch......must be after-market......and the fan clutch, I'm sure is just the bi-metal coil on the clutch which is activated by the air temp through the radiator. The electric doesn't seem to be much help, and may be doing more harm than good (by slowing air flow). That's why I'm thinking that removing the AC condensor will speed air flow through the radiator and....maybe....keep the air cooler and thus keep the clutch from engaging so often. Just wondering what others have done, if anything, to quiet things down.
Jack

23' '85 Itasca Sunflyer, followed closely by:
16' '73 Old Towne FG Canoe

92GA

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  • Posts: 485
    • Pryer Racing
Re: Fan clutch noise and how to quiet it down.
« Reply #7 on: July 22, 2013, 04:38:17 PM »
The fan should cycle with heat. If the fan never slows down then you may have a partially stopped up  radiator. My old Itasca did that before I had the radiator rodded out. After the radiator repair it had regular cycling.  If the fins  are clean, then removing the condenser won't be the only problem as there are many the have it present, not having the problem. Have the radiator flow checked.
95 Damon Challenger 296

catblaster

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  • Posts: 1359
Re: Fan clutch noise and how to quiet it down.
« Reply #8 on: July 22, 2013, 05:59:50 PM »
try one of these:
 http://static.summitracing.com/global/images/prod/mediumlarge/flx-1018_w_ml.jpg
I know these fans don't look like much but they move a lot of air and are the most quiet of all I've run. It's hard to put faith in one configured like this but I know some racers that are running them.

Get one the proper size, eliminate the fan clutch and add the proper spacer with longer bolts. Don't be surprised if the bolts are metric...some are, some are not, depending on the pump.

I would leave the condenser on unless you really don't want it and have to remove it and the radiator to change out fan.

Check out the electric fan closely, I take for granted it is on the front of the radiator blowing towards the motor? The motor will rotate either direction depending on how it is wired but it is much more efficient turning the way it was designed. have seen several installed wrong (some of them I did). If its installed right I would probably leave it, may need it some day just in case.

If you decide to go full electric then check out Dorman products. They make replacement fans for most OEM applications and are much cheaper than the add-on fans. Personally I have had mostly trouble with electric fans, just something more to go wrong. Moisture and vibration are like gremlins waiting to overheat your motor.

Just some suggestions...later Will
Will and Jane
95 Winnebago Luxor
92 Jeep YJ for toad
Got my new air bags,(lungs)
Kissimmee, Fl

92GA

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  • Posts: 485
    • Pryer Racing
Re: Fan clutch noise and how to quiet it down.
« Reply #9 on: July 22, 2013, 07:21:55 PM »
Most all the drag racers I know run an electric fan, but we're not setting up to run hours at a time. We run 1/8 to 1/4 mile at a time. The only guys I know that runs those type of fans are doing so to reduce the pull on the engine at higher rpms. Dought very  much if that fan would pull more air than the stock one.  The stock setup was fine for many years, until a problem arises. Then you have to find the problem, and fix it, not reengineer it.  There are many P30 MH chassis running down the road, and they all don't have this noise, unless they're running hot.

The fan on my rig will engage and disengage  if the temp reaches some where above 210 degrees. It normally runs right at 200, unless it's really hot and humid out. It'll run all the time if in traffic in town.
« Last Edit: July 22, 2013, 08:05:54 PM by 92GA »
95 Damon Challenger 296

denmarc

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Re: Fan clutch noise and how to quiet it down.
« Reply #10 on: July 23, 2013, 10:35:39 AM »
The electric is manual from a dash switch......must be aftermarket......and the fan clutch, I'm sure is just the bi-metal coil on the clutch which is activated by the air temp through the radiator. The electric doesn't seem to be much help, and may be doing more harm than good (by slowing air flow). That's why I'm thinking that removing the AC condensor will speed air flow through the radiator and....maybe....keep the air cooler and thus keep the clutch from engaging so often. Just wondering what others have done, if anything, to quiet things down.

It sounds a bit like you know what you're talking about.  I would bet the bimetallic fan clutch is original.  I also think removing the condenser would be a bad idea (unless defective).  Even if the system isn't working, don't open it up to contaminates which would destroy the rest of the system. 

Catblaster makes some very good points.  I have also used the flex blade fans on engines I have built in past years with no problems.  Having the flow checked through the radiator is also an excellent idea. Maybe the thermostat is stuck open partially causing the engine to run a little hotter than normal?  With an engine of that vintage, the list of possibilities could be quite long. 
Mark

1994 Jayco Eagle 370FB on 24 acres of paid off paradise in Michigan.

Fantasy is a necessary ingredient in living.  It's a way of looking at life through the wrong end of a telescope.

Dr. Seuss

Jack D

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  • Posts: 228
  • Elmira, OR
    • HMDS
Re: Fan clutch noise and how to quiet it down.
« Reply #11 on: July 24, 2013, 01:35:52 PM »
If I were to remove the condensor, I would also remove all traces of the AC system. It really is not needed in this part of the country (Oregon)and when we do need cooling inside the coach, I can always use the roof air. Removing the compressor would decrease the load on the engine some, too. We don't travel much...this coach is a small 23' class A (Itasca) and used mainly for a few days camping (at a time) in the mountains and along the Oregon/Washington coast. Resale value isn't a consideration either. Camping (if you can call it that) in the PNW is our thing and traveling around the country, where temperature variations can swing wildly, is not. It is not worth repairing the in-dash AC for our purposes.

We recently (last week) lost our fan belt (the one that drives the fan, alternator and AIR pump. The engine did not overheat during the 100 mile return trip without the belt. We ran the generator to help keep the batteries up during the return trip and kept all batteries on line to the engine to avoid battery failure until we got home. We were camping on the coast where it was cool and driving into the wind until we started East into the Coast Range of mountains. It was in the low 90's at home, but still the engine temp gauge read normal on our arrival. I believe the fan clutch operates as it should and the cooling system is also operational in the normal range. The noise we hear when the fan clutch is engaged is fan blades beating the air just as all high speed fan blades do. Very similar to an airplane propeller only not as loud. My "Title" for this thread is misleading....it is not the clutch making the noise, it is the blades turning at a high RPM with the clutch engaged.

The most obvious answer seems to be reducing the load on the engine and/or increasing air flow through the radiator. Removing the in-dash AC system would help in this regard, on both fronts, and, perhaps, adding two electrics in front of the radiator. Maybe, just maybe, this would keep the need for the clutch fan to engage at a minimum. I agree with those that say modifying the clutch fan itself would probably not be the best solution, unless there is a proven replacement available. I can't believe we're the only ones with a loud engine cooling fan, so I'm just wondering what, if anything, others have done to "fix" it. We live near the Cascade Mountains and spend a lot of time at our favorite mountain lakes. Climbing that 7% grade on a warm day behind a slow truck means a loud roar all the way to the top and beyond until things cool down.
Jack

23' '85 Itasca Sunflyer, followed closely by:
16' '73 Old Towne FG Canoe

Alfa38User

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Re: Fan clutch noise and how to quiet it down.
« Reply #12 on: July 24, 2013, 03:57:40 PM »
Might make the unit much less attractive for a future sale though, as most people today expect dash air to be available.
Stu
Montreal, Canada
Snowbird, SW Florida
Alfa Gold 38 (2000) 5ver

92GA

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  • Posts: 485
    • Pryer Racing
Re: Fan clutch noise and how to quiet it down.
« Reply #13 on: July 24, 2013, 05:10:58 PM »
 I can't believe we're the only ones with a loud engine cooling fan.

Oh, your not. But know that you explain everything, sounds like it's working as designed.  I don't think removing the condenser will help you at all, if the fins are clean. I'm adding additional heat on mine by running the dash air. If your fan releases at higher engine speeds and the noise goes away, that's what it's supposed to do. Good luck.
95 Damon Challenger 296