Home » Public Forums » GMCnet » Radiator cooling fan
| Radiator cooling fan [message #366807] |
Wed, 15 September 2021 19:20  |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
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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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| [GMCnet] Re: Radiator cooling fan [message #366809 is a reply to message #366807] |
Wed, 15 September 2021 19:32  |
James Hupy
Messages: 6806
Registered: May 2010
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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 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:
>
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| [GMCnet] Re: Radiator cooling fan [message #366819 is a reply to message #366809] |
Wed, 15 September 2021 23:07 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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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 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 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
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Applied/GMC
jimk@appliedairfilters.com
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| Re: Radiator cooling fan [message #366825 is a reply to message #366807] |
Thu, 16 September 2021 14:04 |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
Karma: 0
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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
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| Re: Radiator cooling fan [message #366826 is a reply to message #366807] |
Thu, 16 September 2021 14:12 |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
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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
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| Re: Radiator cooling fan [message #366837 is a reply to message #366807] |
Fri, 17 September 2021 06:35 |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
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Senior Member |
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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
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| Re: Radiator cooling fan [message #366838 is a reply to message #366807] |
Fri, 17 September 2021 06:57 |
tmsnyder
Messages: 151
Registered: January 2014
Karma: -9
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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. You should be able to move it with some resistance but 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
[Updated on: Fri, 17 September 2021 06:58] Report message to a moderator |
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| Re: Radiator cooling fan [message #366839 is a reply to message #366807] |
Fri, 17 September 2021 07:22 |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
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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
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| [GMCnet] Re: Radiator cooling fan [message #366842 is a reply to message #366839] |
Fri, 17 September 2021 09:38 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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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 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
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GMCnet mailing list
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| [GMCnet] Re: Radiator cooling fan [message #366844 is a reply to message #366839] |
Fri, 17 September 2021 10:02 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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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 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:
>
_______________________________________________
GMCnet mailing list
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| [GMCnet] Re: Radiator cooling fan [message #366846 is a reply to message #366807] |
Fri, 17 September 2021 10:46 |
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Ha Ha Ha ! I love that story.
AND that park!
bdub
On Fri, Sep 17, 2021 at 10:38 AM Ken Henderson
wrote:
> Reminds me of our trip across the Texas Panhandle in the summer of about
> '81. We had a '75 Titan motorhome with a Chrysler 318 engine. We were
> cruising along pretty nicely, then I slowed down below 50 mph, and the
> transmission downshifted! I finally found that it did it pretty
> consistently: Below about 50 mph it would downshift to 3rd gear. At
> higher speeds it upshifted again. Finally, we arrived at Palo Duro Canyon
> for the night. I found a 'phone (no cells in those days) and called my old
> F101B pilot buddy in NC, who owned an RV dealership: "What should I tell
> the shop when I take this darned thing in tomorrow?" He got a big kick out
> of that question: "I think your fan clutch is working just fine!"
>
> That one was electrically controlled, so the next morning I added a control
> switch. Sure 'nuff, with that, I could "upshift" at will! :-)
>
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| [GMCnet] Re: Radiator cooling fan [message #366847 is a reply to message #366844] |
Fri, 17 September 2021 10:38 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Reminds me of our trip across the Texas Panhandle in the summer of about
'81. We had a '75 Titan motorhome with a Chrysler 318 engine. We were
cruising along pretty nicely, then I slowed down below 50 mph, and the
transmission downshifted! I finally found that it did it pretty
consistently: Below about 50 mph it would downshift to 3rd gear. At
higher speeds it upshifted again. Finally, we arrived at Palo Duro Canyon
for the night. I found a 'phone (no cells in those days) and called my old
F101B pilot buddy in NC, who owned an RV dealership: "What should I tell
the shop when I take this darned thing in tomorrow?" He got a big kick out
of that question: "I think your fan clutch is working just fine!"
That one was electrically controlled, so the next morning I added a control
switch. Sure 'nuff, with that, I could "upshift" at will! :-)
Ken H.
On Fri, Sep 17, 2021 at 11:02 AM James Hupy wrote:
> 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 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:
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
_______________________________________________
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Re: Radiator cooling fan [message #366852 is a reply to message #366851] |
Fri, 17 September 2021 17:05 |
Bill Van Vlack
Messages: 419
Registered: September 2015
Location: Guemes Island, Washington
Karma: 14
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Senior Member |
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Matt Colie wrote on Fri, 17 September 2021 12:41
I do love this new fan control and will be collecting data about it when we head for Chippewa Falls.
I'll be interested in how you like it; are you using an external sensor or the EBL? If external, where did you put it?
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid November 2015.
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| Re: [GMCnet] Re: Radiator cooling fan [message #366856 is a reply to message #366854] |
Fri, 17 September 2021 23:44 |
Bill Van Vlack
Messages: 419
Registered: September 2015
Location: Guemes Island, Washington
Karma: 14
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Senior Member |
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Matt Colie wrote on Fri, 17 September 2021 21:50
Bill,
I don't have EBL (yet). It is just a switched control but it allows me to feed it a duty cycle to control the the fan speed. All I have is an instrument on the coolant in (a thermocouple) and a per cent duty cycle on the controller.
Matt
Matt,
I have the EBL tie-in that uses the 'Fan On' signal from the EBL, where it's possible to specify fan on/off temperatures using TunerPro. I think it can also turn it on when AC is running if one hooks up a signal from the AC clutch; not sure other logic, if any, affects when the EBL tells the fan to start/stop.
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid November 2015.
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| Re: Radiator cooling fan [message #366860 is a reply to message #366807] |
Sun, 19 September 2021 06:51 |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
|
Senior Member |
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|
Bill and Matt, a little unclear of what you guys are talking of on the cooling fan. It sounds like Matt is running electric cooling fans? If so, could you let me know what your running. I’ve got a EBL in a box along with all the other TBI stuff to install here in the next month or so. Was hoping to verify proper engine temps before I got it installed. If I find the engine running hotter than it should I’d like to get that corrected by either new radiator or a combination of things. So thats where I’m trying to head.
Thanks
TG
Tom Geiger
76 Eleganza II
KCMO
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| [GMCnet] Re: Radiator cooling fan [message #366861 is a reply to message #366860] |
Sun, 19 September 2021 08:38 |
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http://www.gmcmhphotos.com/photos/g7102-mercedes-fan-for-gmc.html
On Sun, Sep 19, 2021 at 6:51 AM tom geiger wrote:
> Bill and Matt, a little unclear of what you guys are talking of on the
> cooling fan. It sounds like Matt is running electric cooling fans? If so,
> could you let me know what your running. I’ve got a EBL in a box along
> with all the other TBI stuff to install here in the next month or so. Was
> hoping to verify proper engine temps before I got it installed. If I find
> the engine running hotter than it should I’d like to get that corrected by
> either new radiator or a combination of things. So thats where I’m trying
> to head.
>
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bdub
bdub.net
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| Re: Radiator cooling fan [message #366862 is a reply to message #366860] |
Sun, 19 September 2021 09:20 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Tom,
What I am running an electrically controlled fan clutch. Right now, it also has a control that can provide a less than 100% duty cycle. The advantage of that is that there is even less noise when it is engaged. It is already substantially quieter than the original, but that is no feat.
Matt - headed north to Chippewa Falls
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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