Connector for engine temp sensor
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Junior User
Joined: Jul 2002
Posts: 59
Likes: 0
Connector for engine temp sensor
I have a '72 F100 w/ 390 and the wire to my water temp sensor has become brittle and cracked exposing wire. I patched in some better wire but I was wondering what would be the best connector since I don't have the "elbow" type. Will a ring or Y connector work? Also, the "screw post" on the sensor turns, is this ok or is it damaged? Thanks!
Post Fiend
Joined: Apr 2002
Posts: 7,157
Likes: 1
From: Central Kali
Connector for engine temp sensor
If the post on the sensor turns, it will probably go open. How about using a nut with a spade type connector? I once checked a sensor with a temp gauge. They are linear up to half scale. Above that, they move less with an increase in temp. So full scale is really hot. 
Elder User
Joined: Jun 2002
Posts: 851
Likes: 0
From: Elizabeth City, NC
Connector for engine temp sensor
So if the post spins it's open. Good info. Don't know if mine does yet. I needed the help with the connector. Thanks guys. When you replace your sensor remember not to use anything on the threads as they provide the ground.
Russell
1968 F250 LWB 300-6
FORD=First on Race Day
#88 Dale Jarrett
#21 Elliott Sadler
#97 Kurt Busch
#28 Ricky Rudd
Russell
1968 F250 LWB 300-6
FORD=First on Race Day
#88 Dale Jarrett
#21 Elliott Sadler
#97 Kurt Busch
#28 Ricky Rudd
Post Fiend
Joined: Apr 2002
Posts: 7,157
Likes: 1
From: Central Kali
Connector for engine temp sensor
You will have coolant all over the place. Drain about 1/2 gallon first.
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Laughing Gas
Joined: Apr 2002
Posts: 869
Likes: 1
From: Apple Valley CA USA
Connector for engine temp sensor
on a stock ford sending unit with a single post the terminal will spin as it is just a contact. if it were open the guage would not peg, as a matter of fact it would not move as power would not flow. if the guage pegs you have a grounded circuit not an open circuit and you can check it by unplugging the sensor and see if it goes down. if not then look for damage to the wire. if it goes down then replace the sender. hawkrod
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Post Fiend
Joined: Feb 2000
Posts: 5,130
Likes: 8
From: Brea CA
Connector for engine temp sensor
I think he was talking about the threaded post itself spinning, not a good thing. You’re right, with the wire shorted to ground, the needle will peg. With the wire open, the needle will drop to nothing.
Mike, you can’t check the temp. sender readings with an ohmmeter and directly correlate them to temperature. The problem is the current that’s pulsed into the sender from the IVR causes a self-heating effect inside the sender. It internally heats the resistance of the thermistor, causing a bias. This is a common occurrence with temperature sensing devices. Fortunately, this self-heating bias is already taken into account in the circuit design so you never see or notice it.
Barry
Mike, you can’t check the temp. sender readings with an ohmmeter and directly correlate them to temperature. The problem is the current that’s pulsed into the sender from the IVR causes a self-heating effect inside the sender. It internally heats the resistance of the thermistor, causing a bias. This is a common occurrence with temperature sensing devices. Fortunately, this self-heating bias is already taken into account in the circuit design so you never see or notice it.
Barry
Post Fiend
Joined: Jun 2002
Posts: 13,873
Likes: 3
From: Atlanta GA
Connector for engine temp sensor
For my senders and contacts on the starter relay, I like to replace the elbows with round lug connectors and secure them with little nuts and a plastic hood. I hate when the oil pressure sender falls off or loses contact because it stalls the truck.
Laughing Gas
Joined: Apr 2002
Posts: 869
Likes: 1
From: Apple Valley CA USA
Connector for engine temp sensor
i am talking about the threaded post spinning. it does not spin when new but original ford ones will spin with age and still work. the post just sits on the internal parts and is not soldered so the post spins. obviously if this was not true his guage would not have read at all because current was still flowing allowing the guage to peg. when i was working at ford there was a TSB on this because mechanics were replacing them by the thousands and ford didn't want to cover them as this is not considered a defect! hawkrod
Post Fiend
Joined: Feb 2000
Posts: 5,130
Likes: 8
From: Brea CA
Connector for engine temp sensor
Hmmm…the post on the original sender in my truck would spin, and it read low too. Hey maybe you can answer why I needed a special temp. sender that only the Ford dealer has (special order) for $60? The replacement senders from NAPA and the others don't work right and all read high. It has to do with the serial number of the truck, I forget what the breakpoint was. They called it a "red top" because the insulator is red on top. My gauges test out ok with the 10, 22.8 and 73 ohm resistor checks just like in my other Fords.
Hey, when did you work for Ford? Do you remember when that TSB came out? I used to work for L/M and still have a lot of those parts and service newsletters.
Barry
Hey, when did you work for Ford? Do you remember when that TSB came out? I used to work for L/M and still have a lot of those parts and service newsletters.
Barry
Laughing Gas
Joined: Apr 2002
Posts: 869
Likes: 1
From: Apple Valley CA USA
Connector for engine temp sensor
the TSB was in the early 80's. i worked for F/L/M dealer until mid 84 when the owner retired and the dealership closed. the different color tops make the guage read in different ranges to soothe the customers concern over vehicles running too hot or too cool. by changing the senders ford is able to set all vehicles up with the same guages and wiring but in a truck the sender may be a little slower to respond and may not send the guage as high or low due to the larger cooling system which gives a little more capacity and the uses of the vehicle which may cause concern under normal conditions. an example that comes to mind is a truck that has a 180 thermostat and a car with a 190. since the guages have the same wiring and mechanism with a different face and needle they will read exactly the same. that is to say the car with the 190 has the guage reading higher than the truck. to make them both sit in the middle ford uses senders with different calibrations. hawkrod
Logistics Pro
Joined: Feb 2000
Posts: 3,565
Likes: 9
From: Sun River St. George
Connector for engine temp sensor
I'd replace the sending unit, they are cheap and monitoring engine temprature is important. I use a double nut with lock washer and ring connector on new wire. But I'm picky about this stuff and like to fix things once, permanently!
William in Atlanta
William in Atlanta