[GMCnet] Mercedes Cooling Fan temperature settings

[Jack Christensen via Gmclist]

Since the previous post has now extended to 2 pages, I'm starting a new post with a focus on fan temperature control.

I've installed a simple PID temperature controller to turn on the fan and provide the option of varying the turn on and off temperature settings
easily. The output of the controller is a pulse width modulated signal based on how far the temperature is from the set temperature, not just a hard
"on" or "off" over a wide range. Based on my intuition and suggestions from the others in the previous posts, I set my unit with a target cold shutoff
temperature of 160 degrees. I then set off on a trip to the GMC 49ers rally in Sacramento. The weather was hot and I was running the air
conditioner.

Per the instructions that come with the kit, I had installed my temperature probe on the passenger side midway between the top and bottom the the
radiator and alongside of the temperature switch provided in the kit which, according to the kit, is set to turn on at 210 and off at 195.

What I found was, that with the AC running, when the temperature at my probe rose to 130 degrees, the water temperature reported from the engine
output to the radiator was over 220 degrees. I'm not sure what it would have been if my setting of 160 degrees was reached as I turned on the fan
manually which quickly brought the temperature at the probe's location down to 100 degrees and the engine water outlet temp to 195.

What this says to me is that the temperature switch in the kit is inappropriate for this location as it would never turn on....well until after bad
things happened. At its current setting it would probably best be installed where the water enters the radiator.

For my drive home, I set the target shutoff of the controller at 115 thinking I could see how the fan behaved when being switched on and off at a rate
inversely proportional to the temperature over 115. Unfortunately we were having rain and it was cold, so no AC, and the radiator output never
reached 115. So more testing needed.

I did come to the conclusion that the fan should be sent a pulse with varied "on" signal until the temperature at the probe drops to around 120.
Also, based on how the temperature at the probe varied with the AC on and off, I can see why modern cars with electric fans are designed to have them
turn them on at some level when the AC is running.

--
Jack Christensen - K6ROW,
'76 Glenbrook/Clasco - "The Silver Bullet",
Sebastopol, CA

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[Terry via Gmclist]

Yes indeed, Capt. Jack 8)
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.

[Jim Kanomata via Gmclist]

I’m of the old school .
I tend to feel that engine temp is ewhere I want the fan sensor to Be. R
I will be conferring with people

On Mon, Mar 16, 2020 at 1:18 PM Terry via Gmclist <gmc...@list.gmcnet.org>
wrote:

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

[Terry via Gmclist]

Thermostat controls engine temperature.
Excess heat transferred to radiator.
Fans shed heat from radiator.
Consider a remote heat transfer station.
Engage thinking... 8)

[John R. Lebetski via Gmclist]

In the automotive world ( the way it's done) the electric fan On temp needs to be at LEAST 10F over the stat temp rating. Usually a bit more because
there is usually a 10F spread in the on to off range to prevent short cycling (hysteresis). This is using engine coolant out temp for ref. A
separate issue is AC. Some turn the fan on with each compressor turn on. Some turn it on low with compressor (low meaning low speed via resistor or
low by 1 of 2 fans) then to high when over a certain hi side pressure or engine temp is reached. What is different here is it takes time for the
clutch to move fluid to the non working chamber, so I would think the Off temp could be closer to the On temp with no hysteresis occurring as fan will
continue to run for roughy 2 minutes after Off command causing a built in overshoot.
--
John Lebetski
Woodstock, IL
77 Eleganza II

[John R. Lebetski via Gmclist]

The stat only controls minimum temp. Setup might work in warm weather, but will run too cold "on the stat" when cooling conditions are better. But
180 is considered an "alternate temp" stock stat on some GM. (Unlike the 160 the Jegs guys go for). The lower the stat temp, the more potential
thermal swing with different conditions. In theory temp swings are bad for gaskets as metals shift. . Probably won't hurt but could keep oil too cold
in cold weather to boil water out of oil. I'm guessing these clutches are more go/no go than infinitely variable.

--
John Lebetski
Woodstock, IL
77 Eleganza II

[Jack Christensen via Gmclist]

Jim K wants to use the temp at the engine to control things. Some of the Fuel Injection systems (maybe all) allow that. Specifically the FiTech
system has that programmable capability via it's temperature sensor usually located in place of the Christmas Tree which would address Jim's concern.
It's strictly on/off with no inherent ability to vary the fan speed, much like the temperature switch provided with the fan kit. It is adjustable,
however, unlike the temperature switch in the kit.

[James Hupy via Gmclist]

I have been watching this thread with a curious intent. Not sure why it's
getting all this attention. The fan has evolved through the years. Started
out being driven by the water pump, and only had a couple of blades. Some
of the very early ones were used on engines that were not even equipped
with water pumps, and were known as thermo-syphon systems. As the engine
heated the coolant, it would rise to the highest point, pulling the cooler
water along with it. That is how the coolant circulates. O.K. for the low
compression, low speed, low horsepower engines of the day. Not very
efficient. Crank driven fans helped with cooling chores. Through the
decades, water pumps, honeycomb radiators, copper and brass materials were
used. Pressurized radiators raised the boiling point of the coolant, and
improved circulation as a result. Along the way, more blades were added to
the fans, along with shrouds and deflectors.
Pretty soon, designers realized that those multi-bladed fans robbed a
bunch of power from the engine, and were very noisy to boot. Thermostats
entered somewhere along the way. Some bright person came up with a self
controlled viscous coupling ( clutch fan) that defied all laws of fluid
dynamics. The fluid was very liquid at cooler temperatures, and became more
thick with a rise in temperature. Unique among fluids. No moving parts.
Bonehead simple. Worked quite well.
So now, we are trying to re-invent the wheel. A difficult undertaking?
Fools errand? Heck, I don't know and am reluctant to speculate on which it
is. It is a tall order in any event. Guess I'll just wait n see.
Jim Hupy
Salem, Oregon

[Ken Burton via Gmclist]

Let's try this again. The thermostat is a cheap and marginally accurate device. For this reason I usually put the original and the new thermostat in
a pan of hot water and heat it. I observe the open and close operation while reading the the water temperature. The thermostat does NOT magically
open fully at the desired temp. It starts to open at around 180 or 195 and SLOWLY opens wider if the temp continues to rise. Mean time whether open
or closed the water pump is circulating the coolant throughout the engine to keep the entire engine at the same temperature. That is what the bypass
hose does near the thermostat and to some extent the cabin heater does too.

When the thermostat is open a limited amount of hot coolant above 180 or 195 is sent from the engine to the radiator. At the time, the same amount of
cooler coolant is returned to the engine to be mixed in with the hotter coolant already there. How much coolant is exchanged is determined by the
thermostat.

So the question now is how does that replacement coolant get cool enough to keep the engine at around 195 or 180? Well that is determined by the
amount of and temperature of the air going through the radiator. We really do not care what temperature the coolant is as it returns to the engine,
EXCEPT when is is not low enough to mix in and lower the engine temperature to the desired 180 or 195.

Notice that we have not even mentioned the fan at this point. It can be zero degrees or 100 degrees outside and the coolant can be running at a
usable temperature. The thermostat will determine how much cooler coolant will be needed to keep the engine temperature at the desired 180 or 195
degrees.

Only when the returned coolant does not have the capacity to cool the engine sufficiently does the fan get involved. So I still maintain that you
determine the maximum temperature that you want the return to the engine coolant to be at and set the fan turn on point there or maybe 5 degrees
lower. You only want the fan running when it is necessary and you do not want the slowness or variable temperatures that the thermostat runs at
affecting the on again / off again cycling of the fan.

You can have the soap box back now.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

[Johnny Bridges via Gmclist]

If you use an analog meter, you can see this action if the pulse repetition rate is fast enough. The needle will fluctuate around the average
voltage.

--johnny
--
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

[Johnny Bridges via Gmclist]

One thing to remember when you use a pulse train to operate the valve in the fan clutch. Since the fluid is fairly viscous the valve isn't going to
snap open and closed as a solenoid would. It will essentially integrate the pulses and open partially, the amount of opening being relative to the
pulse width. You could consider the setup with an on - off temp switch as pulse controlled with very long pulses. There's a range on the M-B fans
which will turn it from about ten percent of shaft revolution to about 90 percent of revolution. Correlate this range to either engine temp or
radiator outlet trem and you can use the amount of air flow needed without overdoing it.

--johnny
--
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

[Matt Colie via Gmclist]

James Hupy wrote on Tue, 17 March 2020 00:12

> I have been watching this thread with a curious intent. Not sure why it's getting all this attention.

> <snip>

> Pretty soon, designers realized that those multi-bladed fans robbed a bunch of power from the engine, and were very noisy to boot.
> Thermostats entered somewhere along the way. Some bright person came up with a self controlled viscous coupling ( clutch fan) that defied all laws
> of fluid dynamics. The fluid was very liquid at cooler temperatures, and became more thick with a rise in temperature. Unique among fluids. No
> moving parts. Bonehead simple. Worked quite well.
> So now, we are trying to re-invent the wheel. A difficult undertaking? Fools errand? Heck, I don't know and am reluctant to speculate on
> which it is. It is a tall order in any event. Guess I'll just wait n see.
> Jim Hupy
> Salem, Oregon

Jim,

As usual, your observations are effective. But you seem to have missed two things....
The temperature controlled fans were installed for Emissions First and CAFE Second. (The five bladed non-harmonic fan was a noise issue.)
The real reason that the new fan control is of interest is that (like the tuning of clutch springs) making these work seems to be a lost art.

When I have Chaumière sitting on tires again, I plan to do more experiments with the fan control mode and set points, but right now, that is nowhere
near the top of my task list.

Oh, and KenB, I am sure that a few more now understand more than they did just a little while ago.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

[James Hupy via Gmclist]

Matt, I didn't mean to imply that high interest in cooling fans was
misplaced use of research and resources that might be better applied to
some other cause. Far from it. I am among those who are quite interested in
where this is headed. My 2006 Chevrolet Trailblazer with the Vortec inline
6 cylinder has an old school viscous clutch fan, engine driven.
However, all my other vehicles have computer regulated, electric motor
driven fans. My Chrysler PT Dream Cruiser is a modern marvel. 4 cylinder,
dual overhead camshaft, 4 valves per cylinder, Turbo Supercharged,
Intercooled, fuel injected engine displacing 2.4 Liters. It puts out 220
SAE net horsepower. The car weighs about 2400 pounds wet. I call these
kinds of cars, "pocket rockets". The computer manages everything from cabin
temperature to transmission shift points to boost pressure, to cooling fan
tip in points as well as speed. All designed as part of the package. And it
works very well. Hardly ever have to even open the hood. Can't get my big
hands in there to fix anything, even if I had too. So complex, old school
diagnostics no longer apply.
Applying this level of technology to a GMC is a tall order. Many of
our coach owners cannot even check their own transmission fluid level
correctly. I am not a luddite by any means. High tech has it's place. I am
just standing back a couple of steps and observing with great interest.
Hope something useful to all of us comes from all this.
Jim Hupy
Salem, Oregon

[jerrod winter via Gmclist]

The early Trailblazer fans were viscous clutch but were controlled by a PWM pulse from the computer. After replacing several of those for many
hundreds of dollars, I've since swapped over to the old school viscous clutch used on the newer trailblazers. Its simple but it doesn't seem to fail
as easily. I went through at least three of the PWM fans in the first 200K miles. I've since put another 160K on the old school fan with no more
issues. I just learned to ignore the service engine light. The controller doesn't like the fact it doesn't see signal from the fan.
--
Jerrod Winter
1977 Palm Beach
Green Jelly Bean
Twin Cities, Minnesota

[Jack Christensen via Gmclist]

Bill,
That's a good question. I'm wondering myself after some quick partial tests while moving. I'm been expecting that the valve opens fully for a short
time based on the pulse width, but it doesn't seem to take a very long pulse for the fan to come on fully. There may be some additional filtering
needed, or perhaps a dc voltage proportional to the pulse width. The experiment continues...

[Johnny Bridges via Gmclist]

It will move part way. This because it's moving in a viscous fluid. This assumes the pulse repetition rate is greater than about ten times the
opening rate.

--johnny
--
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

[Bill Van Vlack via Gmclist]

Some recent posters on FB have had noise complaints with the Mercedes Fan, and I understand that if the fan is slowed down to about 50% there is still
plenty of air movement but little noise. I've found a controller that says that the user can set the PWM frequency from 1 Hz to 99kHz and duty cycle
from 0 - 100%.

This controller is ridiculously inexpensive ($14.00) but given its offshore pedigree there is absolutely no recourse to a manufacturer for support. 

Here's a link.
https://www.amazon.com/gp/product/B081YQW36Z/

Anyone with a MB fan want to try it and report back?

--
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.

[Matt Colie via Gmclist]

I am in the process of doing some other work about the engine, so while there I am going to bury thermocouples ins both coolant in and out. When I
learn more, it will let everybody know. In dynoland, we might control by either one, but I like coolant in as it yields more consistent results.

Matt
--
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

[Bill Van Vlack via Gmclist]

It turns out Applied is now providing an adjustable speed control system with their MB fan kit. That should be a great improvement over the previous
full on/full off controller, available from a stand-up supplier!

--
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.

[78gmcroyale via Gmclist]

Do you have further details?Sent from my U.S.Cellular© Smartphone
-------- Original message --------From: Bill Van Vlack via Gmclist <gmc...@list.gmcnet.org> Date: 10/8/20 12:29 AM (GMT-06:00) To: gmc...@list.gmcnet.org Cc: Bill Van Vlack <bill.va...@gmail.com> Subject: Re: [GMCnet] Mercedes Cooling Fan temperature settings It turns out Applied is now providing an adjustable speed control system with their MB fan kit. That should be a great improvement over the previousfull on/full off controller, available from a stand-up supplier!-- 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 midNovember 2015._______________________________________________GMCnet mailing listUnsubscribe or Change List Options:http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

[Bill Van Vlack via Gmclist]

Quote:
> Do you have further details?

The new version of the MB fan controller is on the Applied site, shown as part of the MB fan kit. It has a PWM speed control dial that you use to set
fan speed percentage and a display that shows the %age setting. I understand that 50% speed is quiet and adequate. I believe it also has a way to set
the on and off temperatures, but it's not obvious from the info on the Applied site. The controller also has an 'override' function which runs the fan
continuously at whatever speed is set by the PWM dial. You'd have to phone Applied to find out whether they are selling it separately and the cost.

It will be interesting to see how folks approach speed settings.

--
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.

[Thomas Pryor via Gmclist]

So Folks, you can go to this site to view Fan and the kit that I supply
APPLIED to install and control the Fan.
https://www.gmcrvparts.com/product-p/g46104.htm
MAKE SURE YOU SEE BOTH PHOTOS. The SECOND image shows the kit contents,
wiring, MB connector, 195/210 degree temp. switch and the Fan 2 controller.

If you want to be assured that the kit is desirable, watch this youtube
clip. https://www.youtube.com/watch?v=vjA_INl9y80&feature=youtu.be

With all that being said, where to put the temperature probe, Matt Colley
is working on instrumenting his radiator and engine for thermal mapping.
Matt you say "I like "coolant in" as it yields more consistent results."
My question is coolant into the engine, or coolant into the radiator? Why?


As a side note, I am working on a stand alone controller that will be
driven by those of you that have an EBL version of the EFI. I'm sure that
most of the other Popular EFI kits could also be employed.

Stay Safe All!

--
Regards,

Tom Pryor
4188 Limerick Dr
Lake Wales, Fl 33859
Cell 248 470 9186

1977 23'B named "CASPER", HARDLY ORIGINAL, (455 EFI) (Pwr. Drive)
(tailgate) (rear bunk beds)
(Webasto petrol boiler) (MB Elect fan clutch) (Brake reaction arms) BUT
STILL A WORK IN PROGRESS!

ReplyForward

[Bill Van Vlack via Gmclist]

Quote:

> As a side note, I am working on a stand alone controller that will be
> driven by those of you that have an EBL version of the EFI. I'm sure that
> most of the other Popular EFI kits could also be employed.

Maybe a selector switch PROBE-EFI-OVERRIDE and just one version. For folks that carry a QJ as a backup to their EFI or change between QJ and EFI or
vice versa at a later date.

--
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.

[John Wright via Gmclist]

Comes up in Youtube as “Video unavailable, this video is private”.

JR Wright

[Michael Hunt via Gmclist]

Yes that's the same thing I got too.

[78gmcroyale via Gmclist]

YouTube video says it's "private".Sent from my U.S.Cellular© Smartphone
-------- Original message --------From: Thomas Pryor via Gmclist <gmc...@list.gmcnet.org> Date: 10/8/20 11:40 AM (GMT-06:00) To: gmc...@list.gmcnet.org Cc: Thomas Pryor <tep...@gmail.com> Subject: Re: [GMCnet] Mercedes Cooling Fan temperature settings So Folks, you can go to this site to view Fan and the kit that I supplyAPPLIED to install and control the Fan.https://www.gmcrvparts.com/product-p/g46104.htmMAKE SURE YOU SEE BOTH PHOTOS.   The SECOND image shows the kit contents,wiring, MB connector, 195/210 degree temp. switch and the Fan 2 controller.If you want to be assured that the kit is desirable, watch this youtubeclip.  https://www.youtube.com/watch?v=vjA_INl9y80&feature=youtu.beWith all that being said, where to put the temperature probe, Matt Colleyis working on instrumenting his radiator and engine for thermal mapping.Matt you say "I like "coolant in" as it yields more consistent results."My question is coolant into the engine, or coolant into the radiator?  Why?As a side note, I am working on a stand alone controller that will bedriven by those of you that have an EBL version of the EFI. I'm sure thatmost of the other Popular EFI kits could also be employed.Stay Safe All!-- Regards,Tom Pryor4188 Limerick DrLake Wales, Fl 33859Cell 248 470 91861977 23'B named "CASPER",  HARDLY ORIGINAL, (455 EFI) (Pwr. Drive)(tailgate) (rear bunk beds)(Webasto petrol boiler) (MB Elect fan clutch) (Brake reaction arms) BUTSTILL A WORK IN PROGRESS!ReplyForward_______________________________________________GMCnet mailing listUnsubscribe or Change List Options:http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

[78gmcroyale via Gmclist]

If we already have the MB system can we buy the new PWM controller?Sent from my U.S.Cellular© Smartphone
-------- Original message --------From: Thomas Pryor via Gmclist <gmc...@list.gmcnet.org> Date: 10/8/20 11:40 AM (GMT-06:00) To: gmc...@list.gmcnet.org Cc: Thomas Pryor <tep...@gmail.com> Subject: Re: [GMCnet] Mercedes Cooling Fan temperature settings So Folks, you can go to this site to view Fan and the kit that I supplyAPPLIED to install and control the Fan.https://www.gmcrvparts.com/product-p/g46104.htmMAKE SURE YOU SEE BOTH PHOTOS.   The SECOND image shows the kit contents,wiring, MB connector, 195/210 degree temp. switch and the Fan 2 controller.If you want to be assured that the kit is desirable, watch this youtubeclip.  https://www.youtube.com/watch?v=vjA_INl9y80&feature=youtu.beWith all that being said, where to put the temperature probe, Matt Colleyis working on instrumenting his radiator and engine for thermal mapping.Matt you say "I like "coolant in" as it yields more consistent results."My question is coolant into the engine, or coolant into the radiator?  Why?As a side note, I am working on a stand alone controller that will bedriven by those of you that have an EBL version of the EFI. I'm sure thatmost of the other Popular EFI kits could also be employed.Stay Safe All!-- Regards,Tom Pryor4188 Limerick DrLake Wales, Fl 33859Cell 248 470 91861977 23'B named "CASPER",  HARDLY ORIGINAL, (455 EFI) (Pwr. Drive)(tailgate) (rear bunk beds)(Webasto petrol boiler) (MB Elect fan clutch) (Brake reaction arms) BUTSTILL A WORK IN PROGRESS!ReplyForward_______________________________________________GMCnet mailing listUnsubscribe or Change List Options:http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

[Steve Weinstock via Gmclist]

So... Just a quick post to keep this thread alive.

I'm keenly interested in this project and will be experimenting with instrumentation to capture temperatures and controllers to regulate fan speed...
I'm also considering a tachometer on the fan for another level of detailed data collection. (I'm thinking that engine speed is also a factor - the
clutch is engaging about a faster spinning shaft - no ??)

I'm messing with a small PID controller (Thank You Captain Jack) and also with some "manual" PWM controllers (Thank You Bill Van Vlack).

And Matt - I'm interested in your instrumentation results too !!

To be continued - what a great community.

Steve W




--
Steve W
1973 : 23'
Southern California

[78gmcroyale via Gmclist]

I'm very interested in this too.Sent from my U.S.Cellular© Smartphone
-------- Original message --------From: Steve Weinstock via Gmclist <gmc...@list.gmcnet.org> Date: 11/3/20 3:16 PM (GMT-06:00) To: gmc...@list.gmcnet.org Cc: Steve Weinstock <steve.w...@cox.net> Subject: Re: [GMCnet] Mercedes Cooling Fan temperature settings So...  Just a quick post to keep this thread alive.I'm keenly interested in this project and will be experimenting with instrumentation to capture temperatures and controllers to regulate fan speed... I'm also considering a tachometer on the fan for another level of detailed data collection.  (I'm thinking that engine speed is also a factor - theclutch is engaging about a faster spinning shaft - no ??)I'm messing with a small PID controller (Thank You Captain Jack) and also with some "manual" PWM controllers (Thank You Bill Van Vlack).And Matt - I'm interested in your instrumentation results too !!To be continued - what a great community.Steve W-- Steve W1973 : 23'Southern California_______________________________________________GMCnet mailing listUnsubscribe or Change List Options:http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

[James Hupy via Gmclist]

It seems to me, that this subject has been kicked around for literally
decades. Fast track back into the past if you will. Back to when we could
still buy OEM fan clutches. Oh, what's that you say? You were still in
elementary school? Well, back in that era, we had a very knowledgeable guy
named Steve Ferguson. He is still around, but has sold his GMC and
purchased a S.O.B. He maintains his membership in Western States, and other
clubs as well. He built a testing platform, powered by an electric fan
motor with an amp draw gage so that he could detect how much load various
fan clutches and fan combinations put on the engine. He tested every fan
clutch on the market, as well as various fans that were available at that
time. He documented that very well, and did a very good presentation at a
few rallies.
As I recall, he was treated quite poorly by some of the GMCMI
membership from the eastern part of the US. I don't remember names, they
are not important, especially in this day and age. But, it taught me a few
things about how to do presentations at rallies, which I still use today.
But today is a different era. Those Mercedes fans were not even
invented, then. Do we really need all that data to tell if our engines are
cool enough, or hot enough? Shoot, I don't know, and as long as my coach
keeps purring down the road, I'm not sure I give a rusty rat's behind. But
I am in the minority, it seems.
Jim Hupy
Salem, Oregon

[Steve Weinstock via Gmclist]

Hello Jim !!

I agree with you - except that I'm a persistent tinkerer with access to too many laboratory devices.

And I had a short stint with a couple of not-completely-properly-functioning (Hayden) fan clutches... that's what put me into this rabbit's hole.
:)

And I remember Steve Ferguson's project too. That was some nice work.

All good in Southern California,

[Jim Kanomata via Gmclist]

Jim H,
You know I supplied all the fan clutches to Steve F for his test.
I have been running this Electronic device forever 60,000 miles all across
the USA and can tell you that on off only is not very great.
It cycles a lot more frequently as once the fan has no power there is very
little rotation of the fan and actually restricts the flow of air through
the radiator so it starts heating up sooner than if the fan was running
30-40 percent after pulling the heat level to 190 degrees.
I have the new one Tom P I purchased from him and installed to test.
Hope to learn if 30-40% is as good as 55% .
The ambient temp being lower will not help me to come up with any great
data.

Just look at the wide cord of the blades

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

[James Hupy via Gmclist]

There is a whole bunch of variables in various years of GMC motorhomes. The
early coaches had different baffles and fans and clutches than the late
coaches do. All was well until the quality of fan clutches went sideways. I
am not against variable speed fans. They have their purposes.
Jim Hupy
Salem, Oregon

[Johnny Bridges via Gmclist]

Steve - the MB fan (and all the others I've seen) have a pulsetrain of the rotating speed, the three center pins. You'll have to chase the proper
polarity, but if you feed it 5 volts and ground, the last pin will give you a pulse train of six pulses per rev. For true RPM, get a cheap tachometer
that's settable. Set it for a six cylinder engine and use some marker and rub off numbers to halve the reading on the tach. You then have true fan
speed. Optionally, you can use a flipflop to divide the pulse train by two and feed it directly to a 6 cylinder tach. For your engine, do the same
with a tach set for 4 cylinders, thus an 8K tach becomes a 4K and is easier to read in your coach. Unless he'sswappedthe dash around, Mike Briere has
this setup in the 23' he got from me.

--johnny
--
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