The Ford Barn

Gezer · 03-14-2018, 02:18 PM

The temp sender in my 51 EAB flat head seems to cause the gauge to read high. (BOILING) The engine never boils over. How do I trace down the issue? Is it the sender or the gauge or both. The engine only has one sender the other head(passenger side) has an elbow for the heater hose.

Open for suggestions.

deuce_roadster · 03-14-2018, 02:24 PM

A short in the wire between sender and gauge I believe will cause it to peg it on the Hot side. The sender should have only 1 wire on it. If it has 2, it is a switch and not a sender and is used with an actual sender. You may try a different sender.

alanwoodieman · 03-14-2018, 02:26 PM

temp gauges read hot when there is no power on, turn on ign and it should go to cold. have you checked for power at the gauge? if power then I would suspect gauge, but if you remove wire from sender what does it do with the ign on? with ign on touch wire to ground, what does it do?

flatheadmurre · 03-14-2018, 02:33 PM

If the gauge reads cold at startup and slowly rise there´s a fair chance the gauge is ok and the sender would be my first suspect.

petehoovie · 03-14-2018, 02:35 PM

Shouldn't the '51 have two senders with a cross over wire between the two?

tubman · 03-14-2018, 03:04 PM

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"petehoovey" - Nope; although it looks like two sensors, the one with one terminal is the actual sender, while the one with two terminals is a switch that opens when the drivers side gets hot and opens and send the gauge to "full hot". (I guess you could call it a "sensor" in that it does respond to changes in temperature.) The actual temperature sensitive mechanism is in the one terminal unit. There are reproductions available, but word is that they are unreliable and short-lived. You are better off finding a good used sensor. These can be repaired. I did it on an experimental basis in this thread : https://www.fordbarn.com/forum/showt...ghlight=sensor.

Gezer · 03-17-2018, 06:32 PM

Mac sender (2).jpg

FYI
I took a Mac temp sender apart. Here is wkat I found. A lot different than th original. The three (?) round things are soldered to the wire then wrapped in the yellow paper separating them from each other. Wires are twisted together and very loosely attached to the peg that the sensor wire attaches to.
I don't know what the round button things are let alone how they work.

flatheadmurre · 03-18-2018, 01:25 AM

Wow... a new low...thoose are NTC resistors...they are temperature sensitive resistors.
Into the junk bin and buy a good used one that doesn´t have resistors in it...just check the opinion on modern gas gauges...this is the same problem but now in a temp sender.

Gezer · 03-19-2018, 09:56 AM

Took the original sender apart. Cleaned it up and put it back together. Used JB Quick Weld to reseal it.
I will install back into the engine today. I will let you know if it was a successful repair or not.

19Fordy · 03-19-2018, 10:04 AM

Gezer: Good idea. I bet it will work better than new.

JSeery · 03-19-2018, 10:41 AM

Quote:

Originally Posted by Gezer

Took the original sender apart. Cleaned it up and put it back together. Used JB Quick Weld to reseal it.
I will install back into the engine today. I will let you know if it was a successful repair or not.

It will be interesting to see your results! Any photos?

Don · 03-22-2018, 06:37 PM

Does the sending unit work the same as the earlier units like the sender unit on 36 gas tank sender and oil pressure sender or the king seals type of gauges,,,have a 8ba in 36 and thinking of remarking a oil pressure gauge and use for temp,,,Don

JSeery · 03-22-2018, 08:31 PM

The principle of operation is all the same, but the physical construction is very different between the different type of senders. They all work using a heater coil on a bi-metal strip that open and closes a set to points. Different mechanical arrangements change the physical pressure on the points which varies the rate at which they open and close and thus the current flow from the gauge to ground. But the arrangements of the guts is very different from one to the other.

03-14-2018, 02:18 PM	#1
Gezer Member Join Date: Apr 2016 Posts: 98	Temp sending unit The temp sender in my 51 EAB flat head seems to cause the gauge to read high. (BOILING) The engine never boils over. How do I trace down the issue? Is it the sender or the gauge or both. The engine only has one sender the other head(passenger side) has an elbow for the heater hose. Open for suggestions.

03-14-2018, 02:24 PM	#2
deuce_roadster Senior Member Join Date: Oct 2011 Location: Shelton, WA Posts: 3,800	Re: Temp sending unit A short in the wire between sender and gauge I believe will cause it to peg it on the Hot side. The sender should have only 1 wire on it. If it has 2, it is a switch and not a sender and is used with an actual sender. You may try a different sender.

03-14-2018, 02:26 PM	#3
alanwoodieman Senior Member Join Date: May 2010 Location: upstate SC Posts: 2,963	Re: Temp sending unit temp gauges read hot when there is no power on, turn on ign and it should go to cold. have you checked for power at the gauge? if power then I would suspect gauge, but if you remove wire from sender what does it do with the ign on? with ign on touch wire to ground, what does it do?

03-14-2018, 02:33 PM	#4
flatheadmurre Senior Member Join Date: Apr 2015 Location: Sweden Posts: 3,045	Re: Temp sending unit If the gauge reads cold at startup and slowly rise there´s a fair chance the gauge is ok and the sender would be my first suspect.

03-14-2018, 02:35 PM	#5
petehoovie Senior Member Join Date: May 2015 Posts: 8,125	Re: Temp sending unit Shouldn't the '51 have two senders with a cross over wire between the two? __________________ The only thing nice about being imperfect is the joy it brings to others.... *"Silver rings, your butt! Them's washers!"* "We shot our way out of that town for a dollar's worth of steel holes!" - from 'The Wild Bunch' - 1969 https://www.youtube.com/watch?v=7NReUd2_0u0

03-14-2018, 03:04 PM	#6
tubman Senior Member Join Date: Dec 2013 Location: Minnesota, Florida Keys Posts: 10,312	Re: Temp sending unit Sponsored Links (Register now to hide all advertisements) "petehoovey" - Nope; although it looks like two sensors, the one with one terminal is the actual sender, while the one with two terminals is a switch that opens when the drivers side gets hot and opens and send the gauge to "full hot". (I guess you could call it a "sensor" in that it does respond to changes in temperature.) The actual temperature sensitive mechanism is in the one terminal unit. There are reproductions available, but word is that they are unreliable and short-lived. You are better off finding a good used sensor. These can be repaired. I did it on an experimental basis in this thread : https://www.fordbarn.com/forum/showt...ghlight=sensor.

03-17-2018, 06:32 PM	#7
Gezer Member Join Date: Apr 2016 Posts: 98	Re: Temp sending unit Mac sender (2).jpg FYI I took a Mac temp sender apart. Here is wkat I found. A lot different than th original. The three (?) round things are soldered to the wire then wrapped in the yellow paper separating them from each other. Wires are twisted together and very loosely attached to the peg that the sensor wire attaches to. I don't know what the round button things are let alone how they work.

03-18-2018, 01:25 AM	#8
flatheadmurre Senior Member Join Date: Apr 2015 Location: Sweden Posts: 3,045	Re: Temp sending unit Wow... a new low...thoose are NTC resistors...they are temperature sensitive resistors. Into the junk bin and buy a good used one that doesn´t have resistors in it...just check the opinion on modern gas gauges...this is the same problem but now in a temp sender.

03-19-2018, 09:56 AM	#9
Gezer Member Join Date: Apr 2016 Posts: 98	Re: Temp sending unit Took the original sender apart. Cleaned it up and put it back together. Used JB Quick Weld to reseal it. I will install back into the engine today. I will let you know if it was a successful repair or not.

03-19-2018, 10:04 AM	#10
19Fordy Senior Member Join Date: May 2010 Location: Coral Springs FL Posts: 10,936	Re: Temp sending unit Gezer: Good idea. I bet it will work better than new.

03-22-2018, 06:37 PM	#12
Don Senior Member Join Date: May 2010 Location: Ashland KY Posts: 1,159	Re: Temp sending unit Does the sending unit work the same as the earlier units like the sender unit on 36 gas tank sender and oil pressure sender or the king seals type of gauges,,,have a 8ba in 36 and thinking of remarking a oil pressure gauge and use for temp,,,Don __________________ DON P

03-22-2018, 08:31 PM	#13
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: Temp sending unit The principle of operation is all the same, but the physical construction is very different between the different type of senders. They all work using a heater coil on a bi-metal strip that open and closes a set to points. Different mechanical arrangements change the physical pressure on the points which varies the rate at which they open and close and thus the current flow from the gauge to ground. But the arrangements of the guts is very different from one to the other.