51 temp sending units?
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New User
Joined: Dec 2006
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51 temp sending units?
Trying to resolve a sending unit issue.
V8 flatty with single pole sender in one bank and dual connection on the other. Converted to 12V, using original gauge and Runtz voltage reducer.
Problem: At 180°F the gauge is one mark from the top and on a hot day it sits on the highest mark. At cold (ambient) the gauge reads about 1/3 and it swings fine as the temp increases, you can even see the stats open and close by the gauge swing.
I'd like to get it back to the mid-point of the gauge. Seems like the 2-post sender (#217) isn't doing much? Resistance between poles is 0.3ohm and doesn't seem to change?? Anyone know what it should be?
Sender (#224) on the other side changes resistance as temperature changes and seems ok. I think it went from 13ohm cold to 66ohm hot.
Anyone run into this and have some good answers?
Thanks.
V8 flatty with single pole sender in one bank and dual connection on the other. Converted to 12V, using original gauge and Runtz voltage reducer.
Problem: At 180°F the gauge is one mark from the top and on a hot day it sits on the highest mark. At cold (ambient) the gauge reads about 1/3 and it swings fine as the temp increases, you can even see the stats open and close by the gauge swing.
I'd like to get it back to the mid-point of the gauge. Seems like the 2-post sender (#217) isn't doing much? Resistance between poles is 0.3ohm and doesn't seem to change?? Anyone know what it should be?
Sender (#224) on the other side changes resistance as temperature changes and seems ok. I think it went from 13ohm cold to 66ohm hot.
Anyone run into this and have some good answers?
Thanks.
Mountain Pass
Joined: Mar 2008
Posts: 230
Likes: 5
From: Northern Virginia
The dual contact sender is essentially an on/off switch. OK or overheating are the only options with that. I just went through this with my 50 flattie and replaced both sensors. I know that one side is moving up and down, the other is either OK or overheated. The new single pole sensor goes about half way and seems to be accurate. I just idled through a 2 hour parade at over 95 degrees and never went over half with the new sensor. Performance and operation seemed to verify the reading - plus no steam out of the cap 
I've read numerous postings about running two gauges on other sites to keep accurate track of both sides and based on comments from this site decided to stick with stock. As ABUQ F-1 said, they worked that way for 60 years, why change.
I've read numerous postings about running two gauges on other sites to keep accurate track of both sides and based on comments from this site decided to stick with stock. As ABUQ F-1 said, they worked that way for 60 years, why change.
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OK, I was reading some other threads after I posted and understand now why the 2 pole sensor shows continuity all the time (so it's OK).
Question, prior to buying your new single pole sending unit did you have a similar issue with the gauge reading hot? If a new sender would resolve the issue I'd just buy one but if not I might try putting a 100ohm resistor in parallel and see if that brings me into the zone it should be.
There's just something pesky about watching a gauge sit on the H even when you know the temp is OK.
Thanks for sharing your experience.
Question, prior to buying your new single pole sending unit did you have a similar issue with the gauge reading hot? If a new sender would resolve the issue I'd just buy one but if not I might try putting a 100ohm resistor in parallel and see if that brings me into the zone it should be.
There's just something pesky about watching a gauge sit on the H even when you know the temp is OK.
Thanks for sharing your experience.
Mountain Pass
Joined: Mar 2008
Posts: 230
Likes: 5
From: Northern Virginia
I would check the resistance with the sensor in a pot of water brought to boil with a thermometer so see if the resistance is proper as the temperature changes. I found the problem that way and replaced the sensor. My dual pole was bypassed by the PO because it had gone bad (no continuity regardless of the temp).
EDIT: You can also check the dual pole at the same time - continuity should break when it gets too hot.
EDIT: You can also check the dual pole at the same time - continuity should break when it gets too hot.
Senior User
Joined: Dec 2009
Posts: 267
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From: Alvin, Texas 77511
i NEVER COULD GET MINE TO WORK LIKE THEY SHOULD EITHER. I CHANGED OUT THE SENDING UNITS 4 TIMES AT A HUNDRED DOLLARS A POP AND THE TEMP GUAGE ALWAYS DID THE SAME GO TO THE NEXT TO LAST MARK ON HOT AND THEN WOULD RISE TO HOT. WE HAVE HAD ABOUT 17 PAGES ON THE FORUM TRYING TO FIGURE IT OUT BUT JUST AS I THOUGHT I WAS GETTING SOMEWHERE WITH IT THE GUAGE WOULD ACT UP. I ALSO CHANGED THE GUAGE THREE TIME AND GOT ONE FROM JULIES COOL THAT WAS CALABRATED WORKED A WHILE BUT BACK TO THE SAME OLD THING. TOOK HEAT LASER GUN AND SHOT THE ENGINE AND IT WAS HOT. SO i FINALLY GAVE UP ON THE ORIGNAL GUAGE AND GOT TWO MECHANICAL GUAGES FROM AUTO ZONE AND NOW IT READS BETWEEN 165 AND 175. I KNOW THEY ARE RIGHT BECAUSE I TESTED THEM IN SOME WATER WITH A TEMP GUAGE. SO I HOPE YOU HAVE BETTER LUCK THAN I DID,LARRY BRAUER
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