Engine Temp Gauge/Sender

[Area 52]

Saturday...gauge was reading 1/3rd from cold with hot engine (normal condition). Didn't go to church Sunday and God's wrath struck my BII engine temp gauge. The gauge started out normal but quickly (within a few minutes from cold engine) moved up to full hot...like the red glow around the edges of hell's door hot.
Therefore, broke out the ohmmeter. Disconnected wire from sender to gauge and measured the sender at 317 ohms cold engine & 77 ohms hot. Repenting and sore from flailing my back...I read through the King Ford Bible...it states to use inline resistors to troubleshoot. 9 ohms for a hot gauge and about 75 ohms for a cold gauge. Therefore...is it safe to say the sending unit is shot if I have 77/317 ohms or might there be a secondary set of resistors up by the gauge or instrument cluster which drops my high readings down before it hits the gauge???

 

[martin]

for the cost of a couple of resistors you will find out right away.

 

[Jspafford]

Best to put in a mechanical guage. Much more accurate. Oh, and if you want, the sending units are less than $20 at any parts store.

 

[Area 52]

Thanks guys...picked up a new sender today for $6...gauge works fine now.

 

[AllanD]

Last time I had a problem with my guage sensor I backed off 1/2turn... then tightened it 1/2 turn tighter than it was when I started....

PRoblem solved.

Remember the resistance in the sender is added to any resistance
between the stud and the manifold, and between the stud and the
slip connector that goes on it.

AD

 

[Area 52]

Allan...I think that is exactly what was occurring (increased resistance to ground). I pulled the old one and set it next to the new sender and at the same temperature they were almost identical in the reading.

Put the new one in and then pulled the thermostat to test it. T/S worked fine and opened like it should in a pan of hot water on the range (180 degree). Reinstalled the T/S...topped off radiator and let it warm up to operating temperature. Reconfirmed T/S by infrared thermometer on the T/S housing...179-181 degree readings. At that temp, the gauge needle was at the letter 'N' in the word Normal. Having just acquired this little beast...I'm running some Prestone cleaner through the system and then double flush it.

Let me ask this...are there any antifreeze brands that could harm the engine/radiator? Thanks again!