Fan Clutch

[emerystora]

What is the current recommendations for a heavy duty fan clutch? I have been using the AC Delco 15-4644 but that is no longer being made.

Emery Stora
77 Kingsley
Frederick, CO

 

[john phillips]

Is there an eclectic fan for in front of the radiator that has
enough airflow for our purpose?

On Thu, Sep 19, 2019 at 5:23 PM Emery Stora via Gmclist <

> What is the current recommendations for a heavy duty fan clutch? I have
> been using the AC Delco 15-4644 but that is no longer being made.
>
> Emery Stora
> 77 Kingsley
> Frederick, CO
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--

*John Phillips*

 

[Jim Hupy]

The Ford super coupe had a pair of fans that would move enough air, they
draw a whole bunch of amps though. What's wrong with the stock set-up? When
all is correct, it works jus' fine.
Jim Hupy
Salem, Oregon

On Thu, Sep 19, 2019, 5:28 PM John Phillips via Gmclist <

> Is there an eclectic fan for in front of the radiator that has
> enough airflow for our purpose?
>
> On Thu, Sep 19, 2019 at 5:23 PM Emery Stora via Gmclist <

>
> > What is the current recommendations for a heavy duty fan clutch? I have
> > been using the AC Delco 15-4644 but that is no longer being made.
> >
> > Emery Stora
> > 77 Kingsley
> > Frederick, CO
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
>
>
> --
>
> *John Phillips*
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[Rdenney]

The problem with the stock setup is that the fan clutches on the market are
questionable, and the good ones are no longer being made. My Delco 4644
still works fine, but fan clutches don’t last forever.

If it dies, I will seriously consider the electric clutch system that JimK
is now selling, the one that Matt Colie was talking about not long ago.

Rick “fan clutches have been flaky for a long time” Denney

On Thu, Sep 19, 2019 at 8:58 PM James Hupy via Gmclist <

> The Ford super coupe had a pair of fans that would move enough air, they
> draw a whole bunch of amps though. What's wrong with the stock set-up? When
> all is correct, it works jus' fine.
> Jim Hupy
> Salem, Oregon
>
> On Thu, Sep 19, 2019, 5:28 PM John Phillips via Gmclist <

>
> > Is there an eclectic fan for in front of the radiator that has
> > enough airflow for our purpose?
> >
> > On Thu, Sep 19, 2019 at 5:23 PM Emery Stora via Gmclist <

> >
> > > What is the current recommendations for a heavy duty fan clutch? I
> have
> > > been using the AC Delco 15-4644 but that is no longer being made.
> > >
> > > Emery Stora
> > > 77 Kingsley
> > > Frederick, CO
> > > _______________________________________________
> > > GMCnet mailing list
> > > Unsubscribe or Change List Options:
> > > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> > >
> >
> >
> > --
> >
> > *John Phillips*
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
'73 X-Glacier 230 "Jaws"
Northern Virginia
Offlist email: rick at rickdenney dot com

 

[jim kanomata1]

Tom Pryor is working to improve the electric fan clutch so it will operate
more efficiently and not come on frequently.
I now have over 40,000 Miles on mine and like the performance and
reliability and have the option to manually control it if needed.

On Thu, Sep 19, 2019 at 6:40 PM Richard Denney via Gmclist <

> The problem with the stock setup is that the fan clutches on the market are
> questionable, and the good ones are no longer being made. My Delco 4644
> still works fine, but fan clutches don’t last forever.
>
> If it dies, I will seriously consider the electric clutch system that JimK
> is now selling, the one that Matt Colie was talking about not long ago.
>
> Rick “fan clutches have been flaky for a long time” Denney
>
> On Thu, Sep 19, 2019 at 8:58 PM James Hupy via Gmclist <

>
> > The Ford super coupe had a pair of fans that would move enough air, they
> > draw a whole bunch of amps though. What's wrong with the stock set-up?
> When
> > all is correct, it works jus' fine.
> > Jim Hupy
> > Salem, Oregon
> >
> > On Thu, Sep 19, 2019, 5:28 PM John Phillips via Gmclist <

> >
> > > Is there an eclectic fan for in front of the radiator that has
> > > enough airflow for our purpose?
> > >
> > > On Thu, Sep 19, 2019 at 5:23 PM Emery Stora via Gmclist <

> > >
> > > > What is the current recommendations for a heavy duty fan clutch? I
> > have
> > > > been using the AC Delco 15-4644 but that is no longer being made.
> > > >
> > > > Emery Stora
> > > > 77 Kingsley
> > > > Frederick, CO
> > > > _______________________________________________
> > > > GMCnet mailing list
> > > > Unsubscribe or Change List Options:
> > > > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> > > >
> > >
> > >
> > > --
> > >
> > > *John Phillips*
> > > _______________________________________________
> > > GMCnet mailing list
> > > Unsubscribe or Change List Options:
> > > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> > >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> --
> '73 X-Glacier 230 "Jaws"
> Northern Virginia
> Offlist email: rick at rickdenney dot com
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502

 

[Larry Davick]

Wow a resurrected thread from 10 years ago -- It's rare when somebody uses the search function - Excellent!
Still, I think the recommendation for old T-Bird SuperCoup electric fans is a good recommendation. The plastic fan from Jim K, or an electric fan
clutch controlled by the EFI is even better!

My fan clutch went out while on my way down to SoCal to pick up my niece. I called Jim K, he gave me a part number, I called a local NAPA parts store
and they delivered to where I was parked! I had a few wrenches and swapped out the thing without costing us more than an hour.

It's the only time we've been sidelined by our coach. 1 hour. No too bad. If you read this site you may think our coaches are nothing but trouble.
Not so.

--
Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy

 

[john phillips]

Jim Hupy "what is wrong with the stock fan clutch?"
Just if the clutch is or becomes hard to get. I am not sure how effective
the clutch is at cutting out when it is not needed and turning on when it
is. It senses air temperature on the hot side of the radiator where an
electric fan could sense return water temperature. I would think that at
highway speeds even when the air is hot comming through the radiator that
you would not need the fan on.

On Thu, Sep 19, 2019 at 9:58 PM Larry Davick via Gmclist <

> Wow a resurrected thread from 10 years ago -- It's rare when somebody uses
> the search function - Excellent!
> Still, I think the recommendation for old T-Bird SuperCoup electric fans
> is a good recommendation. The plastic fan from Jim K, or an electric fan
> clutch controlled by the EFI is even better!
>
> My fan clutch went out while on my way down to SoCal to pick up my niece.
> I called Jim K, he gave me a part number, I called a local NAPA parts store
> and they delivered to where I was parked! I had a few wrenches and
> swapped out the thing without costing us more than an hour.
>
> It's the only time we've been sidelined by our coach. 1 hour. No too
> bad. If you read this site you may think our coaches are nothing but
> trouble.
> Not so.
>
>
> --
> Larry Davick
> A Mystery Machine
> 1976(ish) Palm Beach
> Fremont, Ca
> Howell EFI + EBL + Electronic Dizzy
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--

*John Phillips*

 

[Rdenney]

I’ve heard this a lot, but it does not fit my experience. My engine temps
(measured coolant temps using a good mechanical temp gauge) will rise even
when on the highway, if I’m climbing or it’s a hot day. When the clutch
engages, the temperature is usually in the 190-200 vicinity, and with the
fan being driven, it will drop to 180 or a bit less (where the thermostat
closes) in around 20 seconds. The driven fan is highly effective at
lowering coolant temperatures—ram air is not.

I recall several extended threads years ago about why this would be. My
air-flow path is stock, my radiator is an aluminum Griffin, and the cooling
system is tip-top. A new engine and transmission did not change the
behavior.

So, I am persuaded that we need a functioning fan clutch even at highway
speed.

I do think my clutch is slowly degrading. The engine temperature being
displayed when it engages is about 10-15 degrees lower that if used to be.
I used to see temps in the 210 vicinity when the clutch engaged. If I had a
195-degree thermostat, I don’t know how it would behave, but I think it
would be a fight to the death (of the clutch).

The electric clutch seems like an excellent way to gain some control over
this process. But I’ve spent all my play money this year on making it roll
straight and stop better.

Rick “thinking’s next year’s project may be the fan and maybe a new exhaust
system” Denney

On Fri, Sep 20, 2019 at 2:58 AM John Phillips via Gmclist <

> Jim Hupy "what is wrong with the stock fan clutch?"
> Just if the clutch is or becomes hard to get. I am not sure how effective
> the clutch is at cutting out when it is not needed and turning on when it
> is. It senses air temperature on the hot side of the radiator where an
> electric fan could sense return water temperature. I would think that at
> highway speeds even when the air is hot comming through the radiator that
> you would not need the fan on.
>
--
'73 X-Glacier 230 "Jaws"
Northern Virginia
Offlist email: rick at rickdenney dot com

 

[Jim Hupy]

We have been over this so many times, I have lost count. I KNOW WHAT THE
DIFFERENCE IS. So do many of you out there in gmcnet land. When the viscous
clutch manufacturing went "OFF-SHORE", The state of quality control went
into the toilet. Same with alternators, mechanical fuel pumps, water pumps,
and you name it.
Hayden, an OLD LINE USA manufacturer of fan clutches, had to make some
hard business decisions. Namely, adapt to the NEW WORLD ORDER and go
off-shore, or become another Sears, K-Mart, etc. They went off-shore and
their quality control ceased to exist, but their business offices and
advertising continued to flourish. Lots of highly skilled U.S.A. employees
went searching for new jobs, thanks to global economy. Love it or hate it,
it is the NEW REALITY in replacement parts for obsolete vehicles. Not only
GMC motorhomes were affected. The list is too large for this venue.
So when you indicate that I don't know the differences in how these old
girls are cooled, remember this, I have been working on GM vehicles since
the 1950's, I've been there and back, several times.
It sucks, but it is the reality of the times we live in today.
Jim Hupy
Salem, Oregon

On Fri, Sep 20, 2019, 4:51 AM Richard Denney via Gmclist <

> I’ve heard this a lot, but it does not fit my experience. My engine temps
> (measured coolant temps using a good mechanical temp gauge) will rise even
> when on the highway, if I’m climbing or it’s a hot day. When the clutch
> engages, the temperature is usually in the 190-200 vicinity, and with the
> fan being driven, it will drop to 180 or a bit less (where the thermostat
> closes) in around 20 seconds. The driven fan is highly effective at
> lowering coolant temperatures—ram air is not.
>
> I recall several extended threads years ago about why this would be. My
> air-flow path is stock, my radiator is an aluminum Griffin, and the cooling
> system is tip-top. A new engine and transmission did not change the
> behavior.
>
> So, I am persuaded that we need a functioning fan clutch even at highway
> speed.
>
> I do think my clutch is slowly degrading. The engine temperature being
> displayed when it engages is about 10-15 degrees lower that if used to be.
> I used to see temps in the 210 vicinity when the clutch engaged. If I had a
> 195-degree thermostat, I don’t know how it would behave, but I think it
> would be a fight to the death (of the clutch).
>
> The electric clutch seems like an excellent way to gain some control over
> this process. But I’ve spent all my play money this year on making it roll
> straight and stop better.
>
> Rick “thinking’s next year’s project may be the fan and maybe a new exhaust
> system” Denney
>
> On Fri, Sep 20, 2019 at 2:58 AM John Phillips via Gmclist <

>
> > Jim Hupy "what is wrong with the stock fan clutch?"
> > Just if the clutch is or becomes hard to get. I am not sure how effective
> > the clutch is at cutting out when it is not needed and turning on when it
> > is. It senses air temperature on the hot side of the radiator where an
> > electric fan could sense return water temperature. I would think that at
> > highway speeds even when the air is hot comming through the radiator that
> > you would not need the fan on.
> >
> --
> '73 X-Glacier 230 "Jaws"
> Northern Virginia
> Offlist email: rick at rickdenney dot com
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[john r. lebetski]

I think that the thinking is the engine room becomes pressurized at speed by frontal air compressing under the vehicle. Then there is not enough
pressure differential and tam air effect is not that good. Other vehicles exhibit this as well. We took my friends then new 76 L82 Corvette on s road
trip and at speed the temp would creep up and every few minutes the fan clutch would engage for maybe 45 seconds and pull temp right down. As soon as
it disengaged the slow rise would repeat. More understandable as it was a bottom feeder. I have no problems no matter how hot out at low speeds.
Above 70 my temp starts to edge up. I added the under core support air diverter from Applied and this helped a lot. But not a true fix. Adding gill
vents with an area les than 5% of the radiator area might be helpful at shut down for heat soak but I doubt they do much at speed. Has anyone done
empirical testing?
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[Rdenney]

Jim, you are making my argument. You just explained what’s wrong with the
stock setup.

But I don’t give Hayden a pass. They accepted that low quality. Not all
offshore factories turn out low quality, but they will if the buyer accepts
it.

Hayden clutches, though, were the objects of complaint here for as long as
I remember.

Rick “designs that can’t or won’t be manufactured properly or affordably
are ripe for updating” Denney

On Fri, Sep 20, 2019 at 8:30 AM James Hupy via Gmclist <

> We have been over this so many times, I have lost count. I KNOW WHAT THE
> DIFFERENCE IS. So do many of you out there in gmcnet land. When the viscous
> clutch manufacturing went "OFF-SHORE", The state of quality control went
> into the toilet. Same with alternators, mechanical fuel pumps, water pumps,
> and you name it.
> Hayden, an OLD LINE USA manufacturer of fan clutches, had to make some
> hard business decisions. Namely, adapt to the NEW WORLD ORDER and go
> off-shore, or become another Sears, K-Mart, etc. They went off-shore and
> their quality control ceased to exist, but their business offices and
> advertising continued to flourish. Lots of highly skilled U.S.A. employees
> went searching for new jobs, thanks to global economy. Love it or hate it,
> it is the NEW REALITY in replacement parts for obsolete vehicles. Not only
> GMC motorhomes were affected. The list is too large for this venue.
> So when you indicate that I don't know the differences in how these old
> girls are cooled, remember this, I have been working on GM vehicles since
> the 1950's, I've been there and back, several times.
> It sucks, but it is the reality of the times we live in today.
> Jim Hupy
> Salem, Oregon
>
>
> On Fri, Sep 20, 2019, 4:51 AM Richard Denney via Gmclist <

>
> > I’ve heard this a lot, but it does not fit my experience. My engine temps
> > (measured coolant temps using a good mechanical temp gauge) will rise
> even
> > when on the highway, if I’m climbing or it’s a hot day. When the clutch
> > engages, the temperature is usually in the 190-200 vicinity, and with the
> > fan being driven, it will drop to 180 or a bit less (where the thermostat
> > closes) in around 20 seconds. The driven fan is highly effective at
> > lowering coolant temperatures—ram air is not.
> >
> > I recall several extended threads years ago about why this would be. My
> > air-flow path is stock, my radiator is an aluminum Griffin, and the
> cooling
> > system is tip-top. A new engine and transmission did not change the
> > behavior.
> >
> > So, I am persuaded that we need a functioning fan clutch even at highway
> > speed.
> >
> > I do think my clutch is slowly degrading. The engine temperature being
> > displayed when it engages is about 10-15 degrees lower that if used to
> be.
> > I used to see temps in the 210 vicinity when the clutch engaged. If I
> had a
> > 195-degree thermostat, I don’t know how it would behave, but I think it
> > would be a fight to the death (of the clutch).
> >
> > The electric clutch seems like an excellent way to gain some control over
> > this process. But I’ve spent all my play money this year on making it
> roll
> > straight and stop better.
> >
> > Rick “thinking’s next year’s project may be the fan and maybe a new
> exhaust
> > system” Denney
> >
> > On Fri, Sep 20, 2019 at 2:58 AM John Phillips via Gmclist <

> >
> > > Jim Hupy "what is wrong with the stock fan clutch?"
> > > Just if the clutch is or becomes hard to get. I am not sure how
> effective
> > > the clutch is at cutting out when it is not needed and turning on when
> it
> > > is. It senses air temperature on the hot side of the radiator where an
> > > electric fan could sense return water temperature. I would think that
> at
> > > highway speeds even when the air is hot comming through the radiator
> that
> > > you would not need the fan on.
> > >
> > --
> > '73 X-Glacier 230 "Jaws"
> > Northern Virginia
> > Offlist email: rick at rickdenney dot com
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
'73 X-Glacier 230 "Jaws"
Northern Virginia
Offlist email: rick at rickdenney dot com

 

[johnny]

Consider a clutch with an electrically operated viscous drive. It doesn't shock-load the system because it has the same gentle start as the bimetal,
and you can set the engage temp at any value you want.

--johnny7
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell

 

[Jim Hupy]

Yes, GM did wind tunnel testing on the coach. Greg Birch from Washington
State, who is Alex Birch's grandson, has the actual models used in the
early stages of development. Even back in the stone ages of the late 1960's
- Early 1970's, before many of you were even a glimmer of lust in your
daddys eyes, GM had engineers, really good ones, to figure that stuff out.
The engines produce more heat with increases in load, be that low tires,
head winds, hills, heavy feet, you name it. The real problem TODAY is poor
quality control in replacement parts, combined with alcohol laced gasoline
that only contains 75% of the heat energy of early 1970's gasoline.

But, that is today's reality, it is the environment that we have to work
within. These thin fuels do not meter the same way, or atomize the same
way, or boil at the higher temperatures that existed then. We just have to
find ways to cope with changing conditions, if we want to keep driving
these relics from a bygone era.
Electric fans? Sure. Pulse Width Controllers, sure. Truck parts
adapted for our purposes, sure thing.
One last none GMC bit. I have been up since 04:30 A.M and dressed, had my
morning Decaf coffee, and still waiting for the sorry excuse of a paper
delivery person to bring me an example of another long gone era, the daily
newspaper. You all remember those things, don't you? (Grin)
Jim Hupy
Salem, Oregon

On Fri, Sep 20, 2019, 5:39 AM John R. Lebetski via Gmclist <

> I think that the thinking is the engine room becomes pressurized at speed
> by frontal air compressing under the vehicle. Then there is not enough
> pressure differential and tam air effect is not that good. Other vehicles
> exhibit this as well. We took my friends then new 76 L82 Corvette on s road
> trip and at speed the temp would creep up and every few minutes the fan
> clutch would engage for maybe 45 seconds and pull temp right down. As soon
> as
> it disengaged the slow rise would repeat. More understandable as it was a
> bottom feeder. I have no problems no matter how hot out at low speeds.
> Above 70 my temp starts to edge up. I added the under core support air
> diverter from Applied and this helped a lot. But not a true fix. Adding gill
> vents with an area les than 5% of the radiator area might be helpful at
> shut down for heat soak but I doubt they do much at speed. Has anyone done
> empirical testing?
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[gmcnet1]

Hey Richard, thanks for the levity!

- Christo "it's always fun to read Richard Denney's signature" Darsch
--
Christo Darsch
GMC Nor'easters
1977 Eleganza II - "Komet"
3.50 Power Drive, Disc Brakes, Alcoas
Weymouth, MA

 

[Nelson W]

FWIW, I recently drove my 78 Royale up and down the length of the Blue Ridge parkway / Skyline drive without a functioning fan clutch and encountered no overheating problems. This route has many long climbs where I would shift down and crawl at maybe 35 mph. I don’t miss the loud energy sapping clutch at all. I do have a small electric front of radiator fan for use when stationary, but seldom use it. Also I should note that I only use non ethanol fuel, 455, carb, 3.07 FD, and am towing a Smart car.

Nelson Wright
Belle Isle Fl.
78 Royale rear bath

Sent from my iPad

>
> We have been over this so many times, I have lost count. I KNOW WHAT THE
> DIFFERENCE IS. So do many of you out there in gmcnet land. When the viscous
> clutch manufacturing went "OFF-SHORE", The state of quality control went
> into the toilet. Same with alternators, mechanical fuel pumps, water pumps,
> and you name it.
> Hayden, an OLD LINE USA manufacturer of fan clutches, had to make some
> hard business decisions. Namely, adapt to the NEW WORLD ORDER and go
> off-shore, or become another Sears, K-Mart, etc. They went off-shore and
> their quality control ceased to exist, but their business offices and
> advertising continued to flourish. Lots of highly skilled U.S.A. employees
> went searching for new jobs, thanks to global economy. Love it or hate it,
> it is the NEW REALITY in replacement parts for obsolete vehicles. Not only
> GMC motorhomes were affected. The list is too large for this venue.
> So when you indicate that I don't know the differences in how these old
> girls are cooled, remember this, I have been working on GM vehicles since
> the 1950's, I've been there and back, several times.
> It sucks, but it is the reality of the times we live in today.
> Jim Hupy
> Salem, Oregon
>
>
> On Fri, Sep 20, 2019, 4:51 AM Richard Denney via Gmclist <

>
>> I’ve heard this a lot, but it does not fit my experience. My engine temps
>> (measured coolant temps using a good mechanical temp gauge) will rise even
>> when on the highway, if I’m climbing or it’s a hot day. When the clutch
>> engages, the temperature is usually in the 190-200 vicinity, and with the
>> fan being driven, it will drop to 180 or a bit less (where the thermostat
>> closes) in around 20 seconds. The driven fan is highly effective at
>> lowering coolant temperatures—ram air is not.
>>
>> I recall several extended threads years ago about why this would be. My
>> air-flow path is stock, my radiator is an aluminum Griffin, and the cooling
>> system is tip-top. A new engine and transmission did not change the
>> behavior.
>>
>> So, I am persuaded that we need a functioning fan clutch even at highway
>> speed.
>>
>> I do think my clutch is slowly degrading. The engine temperature being
>> displayed when it engages is about 10-15 degrees lower that if used to be.
>> I used to see temps in the 210 vicinity when the clutch engaged. If I had a
>> 195-degree thermostat, I don’t know how it would behave, but I think it
>> would be a fight to the death (of the clutch).
>>
>> The electric clutch seems like an excellent way to gain some control over
>> this process. But I’ve spent all my play money this year on making it roll
>> straight and stop better.
>>
>> Rick “thinking’s next year’s project may be the fan and maybe a new exhaust
>> system” Denney
>>
>> On Fri, Sep 20, 2019 at 2:58 AM John Phillips via Gmclist <

>>
>>> Jim Hupy "what is wrong with the stock fan clutch?"
>>> Just if the clutch is or becomes hard to get. I am not sure how effective
>>> the clutch is at cutting out when it is not needed and turning on when it
>>> is. It senses air temperature on the hot side of the radiator where an
>>> electric fan could sense return water temperature. I would think that at
>>> highway speeds even when the air is hot comming through the radiator that
>>> you would not need the fan on.
>>>
>> --
>> '73 X-Glacier 230 "Jaws"
>> Northern Virginia
>> Offlist email: rick at rickdenney dot com
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[Larry Davick]

I think there is a good argument to be made for fully baffling the grill to radiator, as they did on the later coaches. Ken H made his from mudflaps and as an unexpected benefit now has a tidy work area under the hood when needed.

If the engine bay is pressurized, then hot air may rise over the radiator and reflow into the radiator.

The fan clutch may see lighter duty if the radiator is only intaking cool air.

My 2cents!

“Another fan of Rick Denney’s sig line!"

Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, CA
Howell EFI + EBL + Electronic Distributor

 

[Ken H.]

Since Larry mentioned my radiator duct, someone may be interested in
details; here they are, in 3 stages (not necessarily chronological nor at
the album dates):

I never really had a cooling problem with the 455 or the 500, but when
there's something that "can" be done, it needs to "be" done, right? Since
early in my GMC experience I'd had a rock hit the lower radiator and
puncture it, I decided to both improve airflow and protect that area with
an under-bumper duct:
http://www.gmcmhphotos.com/photos/g5632-under-bumper-air-scoop-26amp-3b-rock-guard.html

The Chevrolet P-30 Chassis Owners Manual has been a favorite reference of
mine for 25 years or so. It makes a big deal of ensuring that no hot air
from the engine compartment reaches the input to the radiator. The GMC
engineers either didn't read that, or didn't agree, so I though I'd
investigate:
http://www.gmcmhphotos.com/photos/g6117-grille-to-radiator-duct.html

While I didn't really have a good reason to do it, someone wondered whether
the damper doors common to many modern cars were useful. The idea
apparently is that when the fan's not running, it impedes air flow through
the radiator; the dampers should open to relieve the resultant
obstruction. When the fan IS running, the dampers should close to force
air flow through the radiator. I tried to achieve those effects. Did I
succeed? I dunno. My temperature was good before and still is: Sets at
about 198*F despite ANYTHING. But here's what's been riding with me for
about 9 years now, untouched:
http://www.gmcmhphotos.com/photos/g5567-radiator-shroud-modification.html

HTH,

Ken H.

On Fri, Sep 20, 2019 at 11:59 AM Larry Davick via Gmclist <

> I think there is a good argument to be made for fully baffling the grill
> to radiator, as they did on the later coaches. Ken H made his from
> mudflaps and as an unexpected benefit now has a tidy work area under the
> hood when needed.
>
> If the engine bay is pressurized, then hot air may rise over the radiator
> and reflow into the radiator.
>
> The fan clutch may see lighter duty if the radiator is only intaking cool
> air.
>
> My 2cents!
>
> “Another fan of Rick Denney’s sig line!"
>
> Larry Davick
> A Mystery Machine
> 1976(ish) Palm Beach
> Fremont, CA
> Howell EFI + EBL + Electronic Distributor
>
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> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[mark sawyer]

Emery,

For what it's worth, I went through 2 Haydens that did not cool correctly out of the box, and decided to try something different.

Went with the Severe Duty GMB 930-2010 and it's cooled my coach great this summer here in Texas....

Only had it on a few months, but just the fact that it actually worked out of the box makes it better than the Haydens so far...
--
Mark S. '73 Painted Desert,
Manny 1 Ton Front End,
Howell Injection,
Leigh Harrison 4bag and Rear Brakes,
Fort Worth, TX

 

[john phillips]

Cool is the important part but costing is the whole reason to have a
clutch in the first place. How well did the 930-2010 cost?
My fan seems to run all the time.

On Fri, Sep 20, 2019 at 1:00 PM Mark Sawyer via Gmclist <

> Emery,
>
> For what it's worth, I went through 2 Haydens that did not cool correctly
> out of the box, and decided to try something different.
>
> Went with the Severe Duty GMB 930-2010 and it's cooled my coach great this
> summer here in Texas....
>
> Only had it on a few months, but just the fact that it actually worked out
> of the box makes it better than the Haydens so far...
> --
> Mark S. '73 Painted Desert,
> Manny 1 Ton Front End,
> Howell Injection,
> Leigh Harrison 4bag and Rear Brakes,
> Fort Worth, TX
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--

*John Phillips*

 

[Tom Lins]

> What is the current recommendations for a heavy duty fan clutch? I have been using the AC Delco 15-4644 but that is no longer being made.
>
> Emery Stora
> 77 Kingsley
> Frederick, CO
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Jeff Sirum put a Hayden severe duty clutch on my 455 about 6 months ago and so far it seems to be functioning as it should.
At low speed here in FL it engages but once out on the highway at speed it disengages.

--
Tom Lins
St Augustine, FL
77 GM Rear Twin, Dry Bath, 455, FI-Tech EFI, Aluminum Radiator Quad-Bag Suspension Solar Panel
Manuals on DVD
GMC Dealer Training Tapes
http://www.bdub.net/tomlins/