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Radiator cooling fan

TG
tom geiger
Thu, Sep 16, 2021 12:20 AM

I’ve been reading on radiator cooling fans for the motorhome.  Its seems like there is a little trouble in both camps.  The fan clutches seem to
fail but I’m also reading some have questions on the electric fans being dependable.  I put on a new fan clutch years ago and am not sure its
working like it should.  It seems to spin all the time but honestly not sure how these fan clutches are suppose to work.  Anyhow was wondering what
everyone is doing on this now.

Thanks,
TG

Tom Geiger
76 Eleganza II
KCMO

I’ve been reading on radiator cooling fans for the motorhome. Its seems like there is a little trouble in both camps. The fan clutches seem to fail but I’m also reading some have questions on the electric fans being dependable. I put on a new fan clutch years ago and am not sure its working like it should. It seems to spin all the time but honestly not sure how these fan clutches are suppose to work. Anyhow was wondering what everyone is doing on this now. Thanks, TG -- Tom Geiger 76 Eleganza II KCMO
JH
James Hupy
Thu, Sep 16, 2021 12:32 AM

The fan clutch can be tested to see if it is serviceable by trying to move
it when the engine is overnight cold. It should have a great amount of
resistance to turning it by hand. After the engine is at operating temps,
you should be able to easily turn the fan blades. If it locks up and roars
when you pull off the highway, and stop for a red light, etc. I would say
that it is working correctly.
Engine temps? I don't know. The clutches all vary a bit on cut in
/out temps. Hot air activates them, not coolant temps, so shroud
construction or modifications will affect that as well.
About all that I know about them.
Jim Hupy
Salem, Oregon

On Wed, Sep 15, 2021, 5:20 PM tom geiger tgimahiker@gmail.com wrote:

I’ve been reading on radiator cooling fans for the motorhome.  Its seems
like there is a little trouble in both camps.  The fan clutches seem to
fail but I’m also reading some have questions on the electric fans being
dependable.  I put on a new fan clutch years ago and am not sure its
working like it should.  It seems to spin all the time but honestly not
sure how these fan clutches are suppose to work.  Anyhow was wondering what
everyone is doing on this now.

Thanks,
TG

Tom Geiger
76 Eleganza II
KCMO


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The fan clutch can be tested to see if it is serviceable by trying to move it when the engine is overnight cold. It should have a great amount of resistance to turning it by hand. After the engine is at operating temps, you should be able to easily turn the fan blades. If it locks up and roars when you pull off the highway, and stop for a red light, etc. I would say that it is working correctly. Engine temps? I don't know. The clutches all vary a bit on cut in /out temps. Hot air activates them, not coolant temps, so shroud construction or modifications will affect that as well. About all that I know about them. Jim Hupy Salem, Oregon On Wed, Sep 15, 2021, 5:20 PM tom geiger <tgimahiker@gmail.com> wrote: > I’ve been reading on radiator cooling fans for the motorhome. Its seems > like there is a little trouble in both camps. The fan clutches seem to > fail but I’m also reading some have questions on the electric fans being > dependable. I put on a new fan clutch years ago and am not sure its > working like it should. It seems to spin all the time but honestly not > sure how these fan clutches are suppose to work. Anyhow was wondering what > everyone is doing on this now. > > Thanks, > TG > -- > Tom Geiger > 76 Eleganza II > KCMO > _______________________________________________ > GMCnet mailing list > Unsubscribe or Change List Options: >
JK
Jim Kanomata
Thu, Sep 16, 2021 4:07 AM

We provide all type and found that when the engine gets hot, the fan should
roar.
One almost need to have a temperature gage and have it reach around 210-220
degrees.
Tom Pryer came up with a  kit using the Mercedes fan clutch that is
triggered by the temp sensor.
I have been running it for three years and also provide that kit.

On Wed, Sep 15, 2021 at 5:32 PM James Hupy jamesh1296@gmail.com wrote:

The fan clutch can be tested to see if it is serviceable by trying to move
it when the engine is overnight cold. It should have a great amount of
resistance to turning it by hand. After the engine is at operating temps,
you should be able to easily turn the fan blades. If it locks up and roars
when you pull off the highway, and stop for a red light, etc. I would say
that it is working correctly.
Engine temps? I don't know. The clutches all vary a bit on cut in
/out temps. Hot air activates them, not coolant temps, so shroud
construction or modifications will affect that as well.
About all that I know about them.
Jim Hupy
Salem, Oregon

On Wed, Sep 15, 2021, 5:20 PM tom geiger tgimahiker@gmail.com wrote:

I’ve been reading on radiator cooling fans for the motorhome.  Its seems
like there is a little trouble in both camps.  The fan clutches seem to
fail but I’m also reading some have questions on the electric fans being
dependable.  I put on a new fan clutch years ago and am not sure its
working like it should.  It seems to spin all the time but honestly not
sure how these fan clutches are suppose to work.  Anyhow was wondering

what

everyone is doing on this now.

Thanks,
TG

Tom Geiger
76 Eleganza II
KCMO


GMCnet mailing list
Unsubscribe or Change List Options:


GMCnet mailing list
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--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502

We provide all type and found that when the engine gets hot, the fan should roar. One almost need to have a temperature gage and have it reach around 210-220 degrees. Tom Pryer came up with a kit using the Mercedes fan clutch that is triggered by the temp sensor. I have been running it for three years and also provide that kit. On Wed, Sep 15, 2021 at 5:32 PM James Hupy <jamesh1296@gmail.com> wrote: > The fan clutch can be tested to see if it is serviceable by trying to move > it when the engine is overnight cold. It should have a great amount of > resistance to turning it by hand. After the engine is at operating temps, > you should be able to easily turn the fan blades. If it locks up and roars > when you pull off the highway, and stop for a red light, etc. I would say > that it is working correctly. > Engine temps? I don't know. The clutches all vary a bit on cut in > /out temps. Hot air activates them, not coolant temps, so shroud > construction or modifications will affect that as well. > About all that I know about them. > Jim Hupy > Salem, Oregon > > On Wed, Sep 15, 2021, 5:20 PM tom geiger <tgimahiker@gmail.com> wrote: > > > I’ve been reading on radiator cooling fans for the motorhome. Its seems > > like there is a little trouble in both camps. The fan clutches seem to > > fail but I’m also reading some have questions on the electric fans being > > dependable. I put on a new fan clutch years ago and am not sure its > > working like it should. It seems to spin all the time but honestly not > > sure how these fan clutches are suppose to work. Anyhow was wondering > what > > everyone is doing on this now. > > > > Thanks, > > TG > > -- > > Tom Geiger > > 76 Eleganza II > > KCMO > > _______________________________________________ > > GMCnet mailing list > > Unsubscribe or Change List Options: > > > _______________________________________________ > GMCnet mailing list > Unsubscribe or Change List Options: > -- Jim Kanomata ASE Applied/GMC, Newark,CA jimk@appliedairfilters.com http://www.gmcrvparts.com 1-800-752-7502
GC
Greg Crawford
Thu, Sep 16, 2021 7:04 PM

During my dash rebuild, I recently installed an Autometer water temperature gauge in addition to the factory gauge. I have a 10 month old NAPA medium
duty clutch fan that I wondered about as the only time I knew for sure was running was when I start the engine for the first time for the day. After
the water temperature gauge was installed, I cranked the coach up and let it warm while doing some dash and air suspension checks. I have a new
radiator core, all new hoses, and a new Robert Shaw 195 degree thermostat. I kind of forgot about the engine idling while I was working on things, but
when I remembered and went back up front, the temperature was sitting at about 205 degrees. I decided to just watch a minute and see if it got any
hotter. It was about 85 degrees outside with 60% humidity. In just a minute or so, I heard the fan kick in for the first time other than initial start
up. It ran for a couple of minutes and the water temperature went all the way down to 180 degrees. That meant that the thermostat was closing again. I
had checked the thermostat for proper operation on the stove top before installation. I kept watching, and the temp slowly began to rise again. So I
was pretty happy to see that everything seemed to be working as it should. The clutch fan kicked in somewhere between 205-210 on the gauge. I don't
know what the air temp coming past the fan sensor was, but it was probably close to that. So yours should behave similarly. I've been told that a
gunked up radiator may not flow enough water to heat up the radiator fins sufficiently to engage the fan, and that may have been my problem before
recoring my radiator.

Greg Crawford
KM4ZCR
Knoxville, TN

"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags

During my dash rebuild, I recently installed an Autometer water temperature gauge in addition to the factory gauge. I have a 10 month old NAPA medium duty clutch fan that I wondered about as the only time I knew for sure was running was when I start the engine for the first time for the day. After the water temperature gauge was installed, I cranked the coach up and let it warm while doing some dash and air suspension checks. I have a new radiator core, all new hoses, and a new Robert Shaw 195 degree thermostat. I kind of forgot about the engine idling while I was working on things, but when I remembered and went back up front, the temperature was sitting at about 205 degrees. I decided to just watch a minute and see if it got any hotter. It was about 85 degrees outside with 60% humidity. In just a minute or so, I heard the fan kick in for the first time other than initial start up. It ran for a couple of minutes and the water temperature went all the way down to 180 degrees. That meant that the thermostat was closing again. I had checked the thermostat for proper operation on the stove top before installation. I kept watching, and the temp slowly began to rise again. So I was pretty happy to see that everything seemed to be working as it should. The clutch fan kicked in somewhere between 205-210 on the gauge. I don't know what the air temp coming past the fan sensor was, but it was probably close to that. So yours should behave similarly. I've been told that a gunked up radiator may not flow enough water to heat up the radiator fins sufficiently to engage the fan, and that may have been my problem before recoring my radiator. -- Greg Crawford KM4ZCR Knoxville, TN "Ruby Sue" 1977 Royale Rear Bath 403 Engine American Eagle Wheels Early Version Alex Sirum Quad bags
TG
tom geiger
Thu, Sep 16, 2021 7:12 PM

By your description Greg then I guess its working but mine gets up to 205-210 but never drops off that temp ever.  It never gets hotter than that but
never cooler.

TG

Tom Geiger
76 Eleganza II
KCMO

By your description Greg then I guess its working but mine gets up to 205-210 but never drops off that temp ever. It never gets hotter than that but never cooler. TG -- Tom Geiger 76 Eleganza II KCMO
TG
tom geiger
Fri, Sep 17, 2021 11:35 AM

As far as the radiator is concerned, I did have it re-cored 15 years back.  I guess my first step will be to put a test temp gage on it and see what
the temp is.  I too have a aftermarket temp gage on mine and not sure if its reading accurate.  I’ve read thru the radiator temp gage section on the
Fisher site.  My dash temp gage says 1/4 but I don’t know if that’s the original OEM sensor model or the new one as suggested by the Fisher site.
Once I get a true reading on temp I’ll go from there.  We’re going camping so I’ll keep on eye on it and see how it acts on the highway as well
as after I come off and hopefully see the fan clutch kick in.
I’ll report what I see.

Thanks,
TG

Tom Geiger
76 Eleganza II
KCMO

As far as the radiator is concerned, I did have it re-cored 15 years back. I guess my first step will be to put a test temp gage on it and see what the temp is. I too have a aftermarket temp gage on mine and not sure if its reading accurate. I’ve read thru the radiator temp gage section on the Fisher site. My dash temp gage says 1/4 but I don’t know if that’s the original OEM sensor model or the new one as suggested by the Fisher site. Once I get a true reading on temp I’ll go from there. We’re going camping so I’ll keep on eye on it and see how it acts on the highway as well as after I come off and hopefully see the fan clutch kick in. I’ll report what I see. Thanks, TG -- Tom Geiger 76 Eleganza II KCMO
TS
Todd Snyder
Fri, Sep 17, 2021 11:57 AM

How to know if your fan clutch is working:

With engine stone cold (and not running) reach in through the hatch and try to spin the fan blade.  It shouldn't spin.  If it free-wheels or spins
easily it is not working .  That is one common mode of failure.

Now start the engine.  You should hear the roar of the fan for several seconds until the clutch loosens up a bit and then the roar will fade.  This
is normal operation.

If it roars initially and never stops roaring, then the clutch is not releasing.  The clutch is locked up.  This is another mode of failure.

Now go climb a large hill on a hot day.  You should hear the fan kick in and start to roar after you get up the hill a ways.  I often hear mine
start to roar as I'm cresting the hill and starting on the way down.  This is normal operation.

You shouldn't see any major fluctuations in the engine coolant temperature if your cooling system (water pump, thermostat, radiator and fan clutch) is
functioning properly.

Cheers!

Todd Snyder, Buffalo NY
1976 Eleganza II

How to know if your fan clutch is working: With engine stone cold (and not running) reach in through the hatch and try to spin the fan blade. It shouldn't spin. If it free-wheels or spins easily it is not working . That is one common mode of failure. Now start the engine. You should hear the roar of the fan for several seconds until the clutch loosens up a bit and then the roar will fade. This is normal operation. If it roars initially and never stops roaring, then the clutch is not releasing. The clutch is locked up. This is another mode of failure. Now go climb a large hill on a hot day. You should hear the fan kick in and start to roar after you get up the hill a ways. I often hear mine start to roar as I'm cresting the hill and starting on the way down. This is normal operation. You shouldn't see any major fluctuations in the engine coolant temperature if your cooling system (water pump, thermostat, radiator and fan clutch) is functioning properly. Cheers! -- Todd Snyder, Buffalo NY 1976 Eleganza II
TG
tom geiger
Fri, Sep 17, 2021 12:22 PM

Todd, just went out and tested the fan clutch and it did spin with some resistance so I guess its working then.  It is for sure spinning the fan when
I first start it up.  The aftermarket temp gage shows temps in and around 200+ as my OEM gage shows the 1/4 mark.  I may be fine on engine temp but
wanted to check with a accurate temp gage test kit to make sure.  I’ve been having what seems to be knocking that seems to be starting up when
engine is at full temp.  I just want to make sure the engine is operating at proper temps.

Thanks,
TG

Tom Geiger
76 Eleganza II
KCMO

Todd, just went out and tested the fan clutch and it did spin with some resistance so I guess its working then. It is for sure spinning the fan when I first start it up. The aftermarket temp gage shows temps in and around 200+ as my OEM gage shows the 1/4 mark. I may be fine on engine temp but wanted to check with a accurate temp gage test kit to make sure. I’ve been having what seems to be knocking that seems to be starting up when engine is at full temp. I just want to make sure the engine is operating at proper temps. Thanks, TG -- Tom Geiger 76 Eleganza II KCMO
JK
Jim Kanomata
Fri, Sep 17, 2021 2:38 PM

One cannot test the sensitivity to temperature as the coil controles when
it will lock up.
Rotating the blade is but one test, you do need to know that it can lock up
when temp gets in the 210-220

On Fri, Sep 17, 2021 at 5:22 AM tom geiger tgimahiker@gmail.com wrote:

Todd, just went out and tested the fan clutch and it did spin with some
resistance so I guess its working then.  It is for sure spinning the fan
when
I first start it up.  The aftermarket temp gage shows temps in and around
200+ as my OEM gage shows the 1/4 mark.  I may be fine on engine temp but
wanted to check with a accurate temp gage test kit to make sure.  I’ve
been having what seems to be knocking that seems to be starting up when
engine is at full temp.  I just want to make sure the engine is operating
at proper temps.

Thanks,
TG

Tom Geiger
76 Eleganza II
KCMO


GMCnet mailing list
Unsubscribe or Change List Options:

--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502

One cannot test the sensitivity to temperature as the coil controles when it will lock up. Rotating the blade is but one test, you do need to know that it can lock up when temp gets in the 210-220 On Fri, Sep 17, 2021 at 5:22 AM tom geiger <tgimahiker@gmail.com> wrote: > Todd, just went out and tested the fan clutch and it did spin with some > resistance so I guess its working then. It is for sure spinning the fan > when > I first start it up. The aftermarket temp gage shows temps in and around > 200+ as my OEM gage shows the 1/4 mark. I may be fine on engine temp but > wanted to check with a accurate temp gage test kit to make sure. I’ve > been having what seems to be knocking that seems to be starting up when > engine is at full temp. I just want to make sure the engine is operating > at proper temps. > > Thanks, > TG > -- > Tom Geiger > 76 Eleganza II > KCMO > _______________________________________________ > GMCnet mailing list > Unsubscribe or Change List Options: > -- Jim Kanomata ASE Applied/GMC, Newark,CA jimk@appliedairfilters.com http://www.gmcrvparts.com 1-800-752-7502
JH
James Hupy
Fri, Sep 17, 2021 3:02 PM

I will try to explain this one more time. Both Steve Ferguson and I have
presented seminars on this subject more than once, and probably will again,
if the Good Lord allows me enough time.
Fan clutches are filled with a very special silicone fluid that gets
more viscosity when it is heated, unlike hydrocarbon and synthetic oils
that thin out, or less viscous, when they are heated. If you look at the
finned surface of a fan clutch, you will see in the center of it a flat
shaped spring coiled in a circle with several wraps. One end is anchored to
the clutch body, and the other end is connected to linkage that disappears
inside the clutch. That linkage operates a valve that circulates that
viscous fluid to expose it to more driven fin like elements, and that in
turn makes the clutch "lock up" or drive the fan at a speed higher than it
is when the spring is not expanded. Clear as mud, right?
Simple answer, is that it is hot air that has an effect on the spring!
NOT HOT COOLANT. HOT COOLANT heats the air that passes through the
radiator, and that activates the spring, etc, etc.
Remember this. The higher the air flow volume through the radiator,
the less heat is concentrated in a smaller volume of air. So, that is why
the clutches seldom lock up at highway speed, and more when the coach is
moving slower.  Also, the clutch is behind the curve, the coolant has
already gained more heat, reflected in your coolant temp gage indication,
before the air gains enough temp to activate that little spring.
More to it than space allows here, so, catch me at a rally someplace,
and I will explain in detail.
Jim Hupy
Salem, Oregon

On Fri, Sep 17, 2021, 5:22 AM tom geiger tgimahiker@gmail.com wrote:

Todd, just went out and tested the fan clutch and it did spin with some
resistance so I guess its working then.  It is for sure spinning the fan
when
I first start it up.  The aftermarket temp gage shows temps in and around
200+ as my OEM gage shows the 1/4 mark.  I may be fine on engine temp but
wanted to check with a accurate temp gage test kit to make sure.  I’ve
been having what seems to be knocking that seems to be starting up when
engine is at full temp.  I just want to make sure the engine is operating
at proper temps.

Thanks,
TG

Tom Geiger
76 Eleganza II
KCMO


GMCnet mailing list
Unsubscribe or Change List Options:

I will try to explain this one more time. Both Steve Ferguson and I have presented seminars on this subject more than once, and probably will again, if the Good Lord allows me enough time. Fan clutches are filled with a very special silicone fluid that gets more viscosity when it is heated, unlike hydrocarbon and synthetic oils that thin out, or less viscous, when they are heated. If you look at the finned surface of a fan clutch, you will see in the center of it a flat shaped spring coiled in a circle with several wraps. One end is anchored to the clutch body, and the other end is connected to linkage that disappears inside the clutch. That linkage operates a valve that circulates that viscous fluid to expose it to more driven fin like elements, and that in turn makes the clutch "lock up" or drive the fan at a speed higher than it is when the spring is not expanded. Clear as mud, right? Simple answer, is that it is hot air that has an effect on the spring! NOT HOT COOLANT. HOT COOLANT heats the air that passes through the radiator, and that activates the spring, etc, etc. Remember this. The higher the air flow volume through the radiator, the less heat is concentrated in a smaller volume of air. So, that is why the clutches seldom lock up at highway speed, and more when the coach is moving slower. Also, the clutch is behind the curve, the coolant has already gained more heat, reflected in your coolant temp gage indication, before the air gains enough temp to activate that little spring. More to it than space allows here, so, catch me at a rally someplace, and I will explain in detail. Jim Hupy Salem, Oregon On Fri, Sep 17, 2021, 5:22 AM tom geiger <tgimahiker@gmail.com> wrote: > Todd, just went out and tested the fan clutch and it did spin with some > resistance so I guess its working then. It is for sure spinning the fan > when > I first start it up. The aftermarket temp gage shows temps in and around > 200+ as my OEM gage shows the 1/4 mark. I may be fine on engine temp but > wanted to check with a accurate temp gage test kit to make sure. I’ve > been having what seems to be knocking that seems to be starting up when > engine is at full temp. I just want to make sure the engine is operating > at proper temps. > > Thanks, > TG > -- > Tom Geiger > 76 Eleganza II > KCMO > _______________________________________________ > GMCnet mailing list > Unsubscribe or Change List Options: >