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Username Post: Temperature sending unit location for electric fan        (Topic#99327)
1956NY150 
Contributor
Posts: 146
1956NY150
Loc: Central NY
Reg: 11-08-04
05-01-05 01:26 PM - Post#685552    

I need Help getting a location for a another water temp sending unit.
Engine is 1965 327 365 HP Stock
I have a mechanical gauge for my water temp, I need to install another temp sending unit for a electric fan. I would prefer not to install a TEE on top of maniford.
Any Ideas would be appreciated.
Thanks
Bob
1956 150 White/Blk 2Dr 421ci SHP Dart Blk,5sp,4:33 200 4R,3:89,8 pt roll cage, 3800#, >12,000 Power Tour Miles,6000 Drag Week miles,Drag Week 09, 010 11.60@115mph


 
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NWSooner 
Very Senior Member
Posts: 2240

Loc: Far Northwest Valley Phoe...
Reg: 10-05-02
Re: Temperature sending unit location for electric
05-01-05 01:35 PM - Post#685553    
    In response to 1956NY150

Check between the 1 & 3 cylander on your head, thats where I found one for mine but I'm running a Big Block.

Good Luck, NWSooner
Our God is in heaven He does whatever He pleases.

Psalm 115:3


 
NWSooner 
Very Senior Member
Posts: 2240

Loc: Far Northwest Valley Phoe...
Reg: 10-05-02
Re: Temperature sending unit location for electric
05-01-05 01:43 PM - Post#685554    
    In response to 1956NY150

A few weeks back when I was searching for same solution someone posted this,Should be an easy fix too:



It's $35 bones & you can get it here. . . . .

http://www.streetrodstuff.com/Products/1749/

NWSooner
Our God is in heaven He does whatever He pleases.

Psalm 115:3


 
alans 55 
"13th Year" Gold Supporting Member
Posts: 3739
alans 55
Age: 66
Loc: Amarillo, Texas
Reg: 03-20-01
Re: Temperature sending unit location for electric fan
05-01-05 02:11 PM - Post#685555    
    In response to 1956NY150

Here's thought and suggestion I found when I installed mine.

unless you plan on having the fan switched by either a switch or ign switch, besides the temp switch, think of this. if you use a temp sending unit and put it in the engine, when you shut it down the water will stay in the engine until it cools down and the fan just keeps running, since it cools the rad water and not the engine water.

I started that way but ended up using a probe in the radiator. mine is not swtiched and just uses temp to turn off and on. guess I could have switched but got lazy and did not want to run more wires back to the dash. I planned on a fan when I wired it and ran a 10 ga from the starter to the relay. they required a 30 amp fuse on it.

now if it is running when i shut the car down it only runs for a short time, till it cools the water down in the radiator/probe.

my fan control also was pre-wired for a line to a binary switch for the a/c. so far all is working good for me.
Cruzin the Texas Panhandle,1/2 way between somewhere and 1/2 way between nowhere
www.picturetrail.com/alanan55
Drivin'my 55 Chebby 210 and playing w/my
40 Ford coupe 327/4sp/9" found and brought back home after 33 years


 
bler57 
Frequent Contributor
Posts: 1376
bler57
Loc: Laguna Hills, CA.
Reg: 12-25-02
Re: Temperature sending unit location for electric fan
05-01-05 02:34 PM - Post#685556    
    In response to alans 55

Have to agree with alan here. Probe in the radiator between the fins is the best for an electric fan. Otherwise, it will run for quite some time before the engine is cool enough for it to shut off!! Unless you have two batteries, this is the best solution!
Marine Fighter Pilot - 57 150 406 SBC/NOS




 
Rick_L 
Honored Member
Posts: 25838

Loc: Katy, Tx, USA
Reg: 07-06-00
Re: Temperature sending unit location for electric fan
05-01-05 03:24 PM - Post#685557    
    In response to bler57

I guess I don't understand why you want or need to have the fan run after the engine is shut off.

Wire the fan with a relay. The main power to the fan should be direct to the battery. But wire the temperature switch from a key on terminal on the fuse block. That way power to actually run the fan does not go through the ignition switch, but the power to turn it on or off does.

 
HOTRODSRJ 
Valued Contributor
Posts: 2972
HOTRODSRJ
Loc: Heart of Dixie (Georgia)
Reg: 06-25-00
Re: Temperature sending unit location for electric fan
05-02-05 01:45 AM - Post#685558    
    In response to Rick_L

RickL has it right! There is no need to run a fan when parked and the engine off. And always relay the fan feed.

I have experiemented with all kinds of sensor switches. Intake, heads, bottom of the radiator, top of the radiator and the "dry" probe types. The only one that I do NOT recommend is the bottom of the radiator (temperature varies greatly with ambient temperature), then head locations (because they get heat tainted so easily with headers close and are not very accurate), and then the intake or radiator probe locations are very accurate.

I find that the dry probes actually work good and are very reliable. I put one on my Dad's 55 just because it's very accurate, reliable and easy to replace if needbe. Locating them close to the engine hose outlet will give a similar reading to an intake positioned one.

The thing also I like about dry probes if placed strategically, is that when you get going and the airflow thru the radiator is sufficient, this drops the temperature enough to always shut the fan off at speed. For example, if you have a 180 degree thermostat and a 180 degree probe switch, if that switch is sensing at the intake, it always will provide a fan signal to operate the fan...even at highway speeds due to the thermostat regulation. But, if you put that same sensor at about 4" below the inlet to the radiator the fan will come on at low speeds at or around 180ish and cycle there accordingly....but once at speed the airflow will actually bring that portion of the radiator below the 180 degree switching point and shut the fan off.

Otherwise, you have to use a higher fan-off temperature switching point than your thermostat or your fan will run all the time. So, with a 180 thermostat you would need a 190 off point and a 200 on point which would be optimum for an intake positioned sensor.

With head locations......who knows? Your heads may run another 20 degrees hotter and make things more difficult to predict to match your switching point and reality.
Steve"Jack'Stands"Jack




 
alee75681 
Contributor
Posts: 776
alee75681
Age: 44
Loc: Henderson, TX
Reg: 02-20-05
Re: Temperature sending unit location for electric fan
05-02-05 06:21 AM - Post#685559    
    In response to HOTRODSRJ

Could one of you guys offer suggestions for part numbers or manufacturers for the dry temp probes?
Andy Lee
'55 4dr sedan

Andy's Cardomain '55 Chevy site


 
alans 55 
"13th Year" Gold Supporting Member
Posts: 3739
alans 55
Age: 66
Loc: Amarillo, Texas
Reg: 03-20-01
Re: Temperature sending unit location for electric fan
05-02-05 06:36 AM - Post#685560    
    In response to alee75681

here's a link to Jeg's and the one I used on my car. they have a bunch listed. mine uses the probe and is adjustable, has a built in relay, fuse and all wiring for 2nd fan and binary switch for A/C.
perma cool fan control switch
Jeg's has several types, styles and price ranges listed.

alan
Cruzin the Texas Panhandle,1/2 way between somewhere and 1/2 way between nowhere
www.picturetrail.com/alanan55
Drivin'my 55 Chebby 210 and playing w/my
40 Ford coupe 327/4sp/9" found and brought back home after 33 years


 
Thadd 
"12th Year" Gold Supporting Member
Posts: 11152
Thadd
Age: 75
Loc: Rolling Hills, Ca,
Reg: 12-30-01
Re: Temperature sending unit location for electric fan
05-02-05 07:51 AM - Post#685561    
    In response to HOTRODSRJ

Not to steal this thread, but Steve, can you explain how my 55 can register lower than Thermostat temps???
I drove over 100 miles yesterday at mainly freeway speeds (1900RPM) and my temp gauge was reading 170º at times...
I have a PRC crossflow, an Edelbrock water pump with a Spal 16" fan and a Painless relay set up. I have noted that the fan kicks on at 195º indicated and the temp gauge generally shows 180º which is thermostat temp...
Proud member of the BABY BLUE T-SHIRT BROTHERHOOD


 
tobyarnot 
Senior Member
Posts: 282

Loc: Semi-Retired (thks Obama)
Reg: 07-17-04
Re: Temperature sending unit location for electric fan
05-02-05 08:46 AM - Post#685562    
    In response to Thadd

You can buy Hayden #3653 adjustable thermostat from Advanced Auto for less than $20. This is an "air probe" type and comes with the clip to mount the probe to the radiator fins.

http://www.partsamerica.com/ProductDetail.aspx?mfrcode=HAD&mfrpartnumber=3653


Toby
Toby,
Just a plain ol' country boy!


 
Rick_L 
Honored Member
Posts: 25838

Loc: Katy, Tx, USA
Reg: 07-06-00
Re: Temperature sending unit location for electric fan
05-02-05 09:43 AM - Post#685563    
    In response to tobyarnot

If you put your temp sender on the radiator the temperature will be much cooler there than if you have it in the head or manifold. Bottom of the radiator is the coolest spot in your cooling system, the head or manifold is the warmest. So different set temperatures may be in order. The temperature at the radiator outlet should be cooler than thermostat set temperature under many but probably not all conditions.

 
alans 55 
"13th Year" Gold Supporting Member
Posts: 3739
alans 55
Age: 66
Loc: Amarillo, Texas
Reg: 03-20-01
Re: Temperature sending unit location for electric fan
05-02-05 10:14 AM - Post#685564    
    In response to Rick_L

I have my probe just under the inlet on the radiator. figured that way should still have fairly accurate reading from the intake. may still have a little drop but not like at opposite end or bottom.

my mech temp gauge is still in the intake. did have in the head but too close for headers. so far all is working good.

alan
Cruzin the Texas Panhandle,1/2 way between somewhere and 1/2 way between nowhere
www.picturetrail.com/alanan55
Drivin'my 55 Chebby 210 and playing w/my
40 Ford coupe 327/4sp/9" found and brought back home after 33 years


 
HOTRODSRJ 
Valued Contributor
Posts: 2972
HOTRODSRJ
Loc: Heart of Dixie (Georgia)
Reg: 06-25-00
Re: Temperature sending unit location for electric fan
05-02-05 10:59 AM - Post#685565    
    In response to Thadd

Thadd......what type of thermostat do you have? Do you have holes drilled in your thermostat?

Generally speaking, regular thermostats will vary with temperature and pressure. So, it may just be the thermostat causing this. This also may be a predictor of things to come. If it isn't a "balanced" or "high flow" style thermostat I would chuck it for one.

Let's hear more
Steve"Jack'Stands"Jack




 
Anonymous 

Re: Temperature sending unit location for electric fan
05-02-05 12:28 PM - Post#685566    
    In response to HOTRODSRJ

I like the bottom of the radiator with a quality sensor such as we use in big diesel trucks.They come in all temperature ratings and can be normally open or normally closed,so they can be easily tied in with a/c systems with minimum wiring.I find them to be very accurate temperature wise.The thermostat maintains engine water temp,and the sensor in the radiator keeps the coolant there at the temperature you select without running the fans to much.They are quite expensive at around$45 though.They fit very nice in the bottom bung of a griffin radiator

 
Thadd 
"12th Year" Gold Supporting Member
Posts: 11152
Thadd
Age: 75
Loc: Rolling Hills, Ca,
Reg: 12-30-01
Re: Temperature sending unit location for electric fan
05-02-05 01:24 PM - Post#685567    
    In response to HOTRODSRJ

Steve...It is a HD Robertshaw with a hole drilled in it. The temp sender is in the front of the intake.(Blower manifold)
Proud member of the BABY BLUE T-SHIRT BROTHERHOOD


 
HOTRODSRJ 
Valued Contributor
Posts: 2972
HOTRODSRJ
Loc: Heart of Dixie (Georgia)
Reg: 06-25-00
Re: Temperature sending unit location for electric fan
05-02-05 02:54 PM - Post#685568    
    In response to Thadd

Hey Thadd, I have found that thermostats with holes drilled in them never come to full thermostat designed operating temperature and will "degrade" operating temperature at full speed and even idling if the ambient temps are low enough. Maybe in heavy idling in higher ambient temperatures the operational temperature will come up to almost full thermostat temperature cycling points, but you can't see the difference on your gauge.

But think about it this way.....the thermostat does not just slam shut or instantly open in its normal operation. It has a temperature range of operating the valve thru out a variance of openings that provides different outflow (usually +/- 3 or 4 degrees in your type). With holes in the thermostat, this disrupts the engineered/gated flow of the thermostat trickling coolant thru all the time. This in turn allows more cool coolant to be pushed thru the engine literally unregulated by the temperature cycling point of the thermostat. Since your thermostat is always the hottest point of your cooling system and hence anything in front of your thermostat (from a flow standpoint) is cooler than that point, the typical gauge/sensor/indicator will always be cooler (indicate cooler) albeit very close to the regulated point. When you have the thermostat almost shut let's say at 180 degrees, the temperature range of the coolant approaching the sensor is very near the ultimate exit point temperature and thus you cannot see the difference on the scale of the gauge. When you provide these holes that are commonly 3/16" or 1/8" X 3 in the thermostats....well that's a huge opening/shunt (think about 3 holes X 3/16" at the pumps 45ish gallons flow rate and probably at least 55 psi...that's a big leak!)to provide to the regulating gate and the coolant will move faster and thus bring cool coolant to the scene faster ..even if the thermostat is shut. At speed with relatively high flow levels (even at 1900rpms) and especially with high flow pumps which makes this phenom worst (but really is better...did I say that right?) the coolant just gets to the sensor faster due to the increase flow rates at speed. Hence, lower readings that are discernable on the gauge.

I tried "holed" thermostats for a year and gave them up. I have no need to use them because all my pumps have by-passes in them and really there is not another reason to use them and moreover I found that they defeated the temperture management of engines.

Here I am again on my soapbox.....I'll get off now and shut up!
Steve"Jack'Stands"Jack




 
Rick_L 
Honored Member
Posts: 25838

Loc: Katy, Tx, USA
Reg: 07-06-00
Re: Temperature sending unit location for electric fan
05-02-05 03:22 PM - Post#685569    
    In response to HOTRODSRJ

To my knowledge, the only production "traditional" small block that didn't have a bypass from the water pump to the passenger side of the block (and from there to the head) was the 96-99 Vortec engine.

But since there are some crate motors with Vortec heads, I wonder if they use the Vortec block too. Anybody know?

The bypass hole is located below the lower passenger side water pump bolt.

 
PAS55 
Senior Member
Posts: 223
PAS55
Loc: Kemptville Ontario Canada
Reg: 10-11-01
Re: Temperature sending unit location for electric fan
05-03-05 01:43 AM - Post#685570    
    In response to HOTRODSRJ

Can you tell me when I run a 180 thermostat what temp should it close at, in the cold weather up here I start my car and I can watch the gauge it goes up to the 180 then it opens. You see the temp drop to about 140 then it will stay there all day if the air temp doesn't come up. I have had three different stats in they all do the same thing.
http://www.picturetrail.com/PAS55


 
Jims56chevy 
Frequent Contributor
Posts: 2226
Jims56chevy
Loc: chino valley az
Reg: 11-23-04
Re: Temperature sending unit location for electric fan
05-03-05 05:40 AM - Post#685571    
    In response to alans 55

Hey Allen where can I locate this probe you are talking about are there any donor vehicles that I could find this in?
Jims56
56 210 2dr


 
alans 55 
"13th Year" Gold Supporting Member
Posts: 3739
alans 55
Age: 66
Loc: Amarillo, Texas
Reg: 03-20-01
Re: Temperature sending unit location for electric fan
05-03-05 06:36 AM - Post#685572    
    In response to Jims56chevy

don't know of any oem cars that have them. I bought mine new and wanted prewired and relay for my fan. I got mine from Jegs, but there are a lot of vendors out there that have fan control switches. here's the link to the fan (2100 cfm and inexpensive, and reversable) and link to the fan control
16" 2100 cfm fan
perma cool fan switch

alan
Cruzin the Texas Panhandle,1/2 way between somewhere and 1/2 way between nowhere
www.picturetrail.com/alanan55
Drivin'my 55 Chebby 210 and playing w/my
40 Ford coupe 327/4sp/9" found and brought back home after 33 years


 
Jims56chevy 
Frequent Contributor
Posts: 2226
Jims56chevy
Loc: chino valley az
Reg: 11-23-04
Re: Temperature sending unit location for electric fan
05-03-05 06:43 AM - Post#685573    
    In response to alans 55

Thanks Allen that should do it.
Jims56
56 210 2dr


 
Thadd 
"12th Year" Gold Supporting Member
Posts: 11152
Thadd
Age: 75
Loc: Rolling Hills, Ca,
Reg: 12-30-01
Re: Temperature sending unit location for electric fan
05-03-05 10:16 AM - Post#685574    
    In response to Thadd

Steve...Thanx
I think that the zigs and zags that this thread has made prove that there are a bunch of us who still don't fully understand cooling system issues....And I have read every word that I have seen since you explained that there is no such thing as holding coolant in the radiator longer to make it cool better
Proud member of the BABY BLUE T-SHIRT BROTHERHOOD


 
5Larry7 
"11th Year" Silver Supporting Member
Posts: 1762
5Larry7
Loc: Dallas, TX
Reg: 05-17-04
Re: Temperature sending unit location for electric fan
05-03-05 11:10 AM - Post#685575    
    In response to Thadd

For what it's worth, I am running the same Perma Cool switch that Alans55 is talking about and I am very happy with results.
'57 210, Blown 327 cid, Holley HP TBI, 700R4, A/C
'51 Studebaker Starlite coupe, 350, TH400, GV OD.
'96 Replica of a 1950's Teardrop Trailer.


 
HOTRODSRJ 
Valued Contributor
Posts: 2972
HOTRODSRJ
Loc: Heart of Dixie (Georgia)
Reg: 06-25-00
Re: Temperature sending unit location for electric fan
05-03-05 11:32 AM - Post#685576    
    In response to PAS55

Hey there Garry......let me ask you a question first. Are you using "holed" thermostats? If you don't know what that means they look like this.



While the Robert Shaw "balanced" or "high flow" thermostats are very good and the most accurate thermostats....the holes shown in the body screw things up in-so-far as temperture management. These holes are for high flow pumps with NO internal or external bypasses only.

The mear presence of these holes will offer a degraded temperature reading as the ambient temperature drops. It even could be that at very cold ambient temperatures the required flow rate to keep the sufficiently engine cool (without the holes) is exceeded by just the holes shunting coolant thru the thermostat itself, even if the thermostat is completely shut!

If you do not have this type of holes, and I do recommend the Robert Shaw or Mr. Gasket "balanced" type of thermostats, then something is up with your thermostats that you are using? If you are using the cheapo regular thermostats, I recommend trying the above without holes.....available from Summit or Jegs for about $10.

Thadd....thanks for the cuddos...I try to give back to the community here whereas I take alot. Hard to keep up!

Rick....all the sbc Vortec headed engines I have seen have provisions for the bypass.

Here is a pic of the 330/350HO right out of the crate! As you can clearly see, bypass provision hole.



If you know of a small block without a bypass I would like to know?? Never seen one myself.

 
PAS55 
Senior Member
Posts: 223
PAS55
Loc: Kemptville Ontario Canada
Reg: 10-11-01
Re: Temperature sending unit location for electric fan
05-03-05 02:06 PM - Post#685577    
    In response to HOTRODSRJ

I am not using the hole type I am using Stant heavy duty high flow, it seems to open at the right temp when you first start the car but it doesn't seem to close again, doesn't seem to matter how cold it gets. The weather is in the 40 's here and it will not run hotter than 150.
http://www.picturetrail.com/PAS55


 
Rick_L 
Honored Member
Posts: 25838

Loc: Katy, Tx, USA
Reg: 07-06-00
Re: Temperature sending unit location for electric fan
05-03-05 02:59 PM - Post#685578    
    In response to HOTRODSRJ

"Here is a pic of the 330/350HO right out of the crate! As you can clearly see, bypass provision hole."

I think the pic answers my question. I didn't know of any that don't have that hole besides the Vortec production engine.

 
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