Where did you put ur temp sensor for an electronic fan clutch?

[jess bressi]

Greetings all. Just purchased an electric fan clutch from Applied (thanks Jim!). Question, where would you install the temp sensor? Lower radiator
hose, upper radiator hose or intake manifold? Advance Adapters and Davies Craig sell inline radiator hose adapters so you don't have to squeeze it
between the hose and outlet and hope the worm drive clamps seal without crushing the capillary line. I understand Tom Pryor prefers the lower hose.
TIA
--
Jess Bressi
Orange County, CA
1972 and 1974 Cortez's
455's/3.07's/Patterson Q-Jets

 

[Matt Colie]

> Greetings all. Just purchased an electric fan clutch from Applied (thanks Jim!). Question, where would you install the temp sensor? Lower
> radiator hose, upper radiator hose or intake manifold? Advance Adapters and Davies Craig sell inline radiator hose adapters so you don't have to
> squeeze it between the hose and outlet and hope the worm drive clamps seal without crushing the capillary line. I understand Tom Pryor prefers the
> lower hose. TIA

Jess,

In engine testing, we always control and watch the water-in temperature. (Tom said that because we talked about it a some length.)

The lower hose is the preferred location for control that way the water out reflects what the engine is actually doing.

I should look up those adapters. I am still running a hard set point switch where there was a tapped hole.

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

 

[jess bressi]

Matt, thanks. The Davies Craig iteration is Part No. DC0409 for $32.47 and the Advance Adapter one is Part No. 716677 for $65.99 from Summit Racing,
Jegs or Amazon. Amazon shows some others for $10 with 1/8" NPT ports but no fittings to reduce down and seal the temp probe.
--
Jess Bressi
Orange County, CA
1972 and 1974 Cortez's
455's/3.70's/Patterson Q-Jets

 

[jess bressi]

Jim K., are you listening? IMHO, the in line hose adapter for the temperature probe should now be part of the kit.
--
Jess Bressi
Orange County, CA
1972 and 1974 Cortez's
455's/3.70's/Patterson Q-Jets

 

[LarryW]

> The lower hose is the preferred location for control that way the water out reflects what the engine is actually doing.
>
> Matt

Lower hose?? Water out is upper....isn't it?
--
Larry
78 Royale w/500 Caddy
Menomonie, WI.

 

[SteveW]

Greetings !!

I've got mine on the intake manifold... but am intrigued by these alternative locations.

There once was discussion about proportional control rather than the current on/off method of fan engagement. Any news on that front ??

Thanks,
Steve W
1973 23' Yellow
Southern California

--
Steve W
1973 : 23'
Southern California

 

[jess bressi]

Matt, Larry has a point. Isn't the lower hose the suction line to the water pump after the radiator has done its job and the upper hose is the
post-thermostat hot water coming out of the intake manifold and going to the radiator? If so, wouldn't the upper hose be a better indicator of engine
temperature? Also, the sending units for temperature gauges are installed in the same water flow in the front of the intake manifold so what were
GM's engineers thinking? Please solve my confusion over this.
--
Jess Bressi
Orange County, CA
1972 and 1974 Cortez's
455's/3.70's/Patterson Q-Jets

 

[jim kanomata1]

Installing a sensor by pearling the hose is not recommended when there is
pressure and the owner of the coach cannot recall when it was done .
Talk with Tom Pryor and see what he recommends.
I prefer to have the sensor on the engine.

On Tue, Mar 3, 2020 at 3:12 PM Steve Weinstock via Gmclist <

> Greetings !!
>
> I've got mine on the intake manifold... but am intrigued by these
> alternative locations.
>
> There once was discussion about proportional control rather than the
> current on/off method of fan engagement. Any news on that front ??
>
> Thanks,
> Steve W
> 1973 23' Yellow
> Southern California
>
>
> --
> Steve W
> 1973 : 23'
> Southern California
>
> _______________________________________________
> 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.gmcrvparts.com
1-800-752-7502

 

[Matt Colie]

Jess, Larry, Steve and anybody else.

Detroit puts the engine temperature sensor in the water out because that is what will best indicate an overheat condition. The thermostat is there
for another very simple reason - Cost. If you really want to regulate an engine's operating temperature, you need to control the temperature of the
coolant entering the system. If you look at the high-buck engines you will see the thermostat is not in the coolant out.

If one really wants to know what is happening, you want to watch both sides of the coolant. The coolant in temperature will tell if your cooling
system is capable at current loads. If that goes up, the only answer is that you have a big problem coming unless you can unload the engine. With
the coolant in controlled, the coolant leaving the engine will be responsive to the actual engine condition.

Why have I not moved my control to the coolant in side when I have a control to do it waiting on the shelf??
Very simple, I installed the new fan and very soon after that a piston shed some rings and I had to take the engine out. Then in the spring of the
next year we had a problem with a lower control arm that has kept the coach on light duty for the next year. I have to have the coach up and running
for a time with some added instrumentation to determine what I want for a coolant in temperature. That will take a day's highway run to calibrate the
fan control, and that is after I install two thermocouples that I trust. When I know that value, then I can tell others. Fortunately, when I have
determined a good set point for coolant in, that will be true for virtually all 455 coaches (regardless of the radiator installed) and may also be
good for 403 and 500. It will also make the optimal ignition timing more stable.

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

 

[jess bressi]

Matt, thanks for sharing your test cell/engine dyno wisdom with a shade tree mechanics like me, I'm a tad less confused. So after I read you last
posting a couple of times, would it be fair to summarize the suggested approach as: (i) installing the probe in the lower/coolant in radiator hose and
(ii) then setting the trigger on temperature of the control unit to something lower than 210 degrees F (say 180) as the starting point? Then after
driving it around and seeing what the coolant temperature does, adjusting the trigger on temperature up or down to maintain a constant 195?
--
Jess Bressi
Orange County, CA
1972 and 1974 Cortez's
455's/3.70's/Patterson Q-Jets

 

[Matt Colie]

> Matt, thanks for sharing your test cell/engine dyno wisdom with a shade tree mechanics like me, I'm a tad less confused. So after I read you last
> posting a couple of times, would it be fair to summarize the suggested approach as: (i) installing the probe in the lower/coolant in radiator hose
> and (ii) then setting the trigger on temperature of the control unit to something lower than 210 degrees F (say 180) as the starting point? Then
> after driving it around and seeing what the coolant temperature does, adjusting the trigger on temperature up or down to maintain a constant 195?

Jess,

You have exactly the correct approach. I wish I could tell you what a good set point would be, but I haven't had a chance to do that yet.
Again, if you have questions, I'm here a lot and am glad to provide the answers that I can.

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

 

[Ken B]

What is the purpose of the fan? It is to extract additional heat from the radiator when normal air flow is not extracting enough heat.

How do we tell how much heat has been extracted? By monitoring the temperature of the coolant leaving the radiator and going back to the engine in
the lower radiator hose.

The need for more or less coolant flow through the engine is determined and regulated by the thermostat in the engine. This flow determines the
engine operating temperature.

Even on an engine driven fan, the engagement is determined by the by temperature and amount heat coming out of the radiator, and not by the engine.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[jess bressi]

So there seems to be a consensus among several of the big engine brains (Mat and Ken) active on this site on probe location, lower radiator hose. Now
the question is what trigger temperature to use? 180 degrees F with a 195 thermostat? All suggestions appreciated in advance.
--
Jess Bressi
Orange County, CA
1972 and 1974 Cortez's
455's/3.70's/Patterson Q-Jets

 

[terry1]

Don't make the connection between the thermostat and the temperature setting of the fan switch, it isn't there. As Ken said, fans cool the radiator,
not the engine. The sensor must go in the output of the radiator, either in the lower hose or the lower tank if there is a bung for it. The thermostat
controls engine temp by monitoring engine heat output and controlling the flow of the coolant after it feels the results of the engine system. It
works the same for the fans, i.e.,control the system AFTER you measure the results, just like oxygen sensors on later vehicles.

If you set the fan activation at 180, you have very little margin left over for the engine to add heat to the coolant on its passage through the
engine. You want the radiator to be able to furnish coolant to the engine as cool as possible to increase that margin, especially in the case of our
motor homes with the engine covered quite closely on top. You need to make sure the fans are on when idling in traffic on an 80 degree day. I would
prefer to have the fans switch on about 160 and have an automatic override for A/C and a manual override for charging up a mountain or possible
failure of the sensor circuitry.
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.

 

[Ken B]

I totally agree with Terry, but I am not sure about the off / on temps. Considering that the fan is there as a back up for use with unusual heat
loads. Normally it should be off except for those abnormal times when additional cooling is required. If you set it too low then it will come on
when not necessary.

I had a set of Hayden clutches one time that did just that. The clutch engaged most of the time which you do not want. I would go with Terry's
recommendation but be ready to modify the on / off temps based on your driving experience.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[Matt Colie]

> So there seems to be a consensus among several of the big engine brains (Mat and Ken) active on this site on probe location, lower radiator hose.
> Now the question is what trigger temperature to use? 180 degrees F with a 195 thermostat? All suggestions appreciated in advance.

Jess,

My scientific wild ass guess would be something closer to 160°F for a 195° thermostat.
But, as I said in a post above, I have not yet done that experiment. When I do, I will publish the information.

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

 

[SteveW]

Greetings -

I'm now seriously considering moving the sensor to the lower radiator hose...

I was unable to locate the adapter with the specified part number. Some poking around and I found:

Advanceadapters.com 716674

I'll keep y'all posted if and when it happens.

Thank you all for sharing your expertise here... I certainly have been a beneficiary.

Steve W
1973 23' Yellow
Southern California

--
Steve W
1973 : 23'
Southern California

 

[johnny]

Consider if you will, a bit of research on your coach. Assume you're going to put >something< in the lower (outlet) of the radiator, probably ain in
hose fitting is the easiest. So, why not before you jump, put a temp sensor at the outlet. Yiu've got one on the inlet already in the gague cluster.
Don't so much care where it runs - usually, but you care when it changes. Engine outlet jumps with a load - say a mountain or freeway on ramp - but
radiator outlet stays close to where it was, you have the temp rise in check. When both start to rise you need to take action. Turning a fan on is a
common action.
I'd watch it, but with the idea of putting the fan temp probe, regardless what type it is* To which I'd add an override switch and a tachometer.;
both simple enough if you have an old tach kicking around. Set it for six cylinder, and renumber the tach face to half value - 8K becomes 4K.
You can get ruboff letter sets which will work if you're careful. The fan clutch has three pins with a Hall effect sensor that should give you 6
pulses per rev.

--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

 

[jess bressi]

FYI, if you have the fan control that uses a 3/8" NPT threaded-in probe rather than the push in capillary style probe, I found a less expensive
radiator hose adapter for the fan control sensor, $10 on Amazon. I ordered the 40 MM model and received it today. I'll need to drill out and re-tap
the 1/8" NPT to 3/8" NPT but several reviewers of the part have already successfully done this. It is called a "Dewhel Aluminum Black Water Temp
Meter Temperature Gauge Joint Pipe Radiator Sensor Adapter 40mm"

I also spoke to Tom Pryor (the inventor of this wonderful device) about the trigger temperature to use for the fan control. He disagrees with
suggestions of the 160 degree F trigger ("the fan will fun continuously") and said he thinks 200 F is the way to go. I think I'll try 200 and see
what happens. Looks like I'll be watching my temperature gauge (it is a real gauge marked in degrees, not just colors or words) like a Hawk and
hitting the fan clutch override on switch if it runs too hot and the fan hasn't kicked on. After I get it all installed, I'll report back on how all
of this is working.

--
Jess Bressi
Orange County, CA
1972 and 1974 Cortez's
455's/3.70's/Patterson Q-Jets

 

[Matt Colie]

> FYI, if you have the fan control that uses a 3/8" NPT threaded-in probe rather than the push in capillary style probe, I found a less expensive
> radiator hose adapter for the fan control sensor, $10 on Amazon. I ordered the 40 MM model and received it today. I'll need to drill out and
> re-tap the 1/8" NPT to 3/8" NPT but several reviewers of the part have already successfully done this. It is called a "Dewhel Aluminum Black Water
> Temp Meter Temperature Gauge Joint Pipe Radiator Sensor Adapter 40mm"
>
> I also spoke to Tom Pryor (the inventor of this wonderful device) about the trigger temperature to use for the fan control. He disagrees with
> suggestions of the 160 degree F trigger ("the fan will fun continuously") and said he thinks 200 F is the way to go. I think I'll try 200 and see
> what happens. Looks like I'll be watching my temperature gauge (it is a real gauge marked in degrees, not just colors or words) like a Hawk and
> hitting the fan clutch override on switch if it runs too hot and the fan hasn't kicked on. After I get it all installed, I'll report back on how
> all of this is working.

Jess,

Tom is probably correct. As I said, I have not run the experiment.

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