1957 gas gage always reading full

[Bill Balkie 24172]

My gas gage always reads full , Although sometimes, but not to often it reads accurately .Last year i removed the tank to change the sending unit Gasket . I started having trouble shortly afterwords . Any ideas on this problem would be appreciated .

 Thanks Bill

[TJ Hopland]

I dont know anything about a 57 but in general I would assume that that vintage would only have one wire to the sending unit so grounds become important.  Perhaps when you had the tank out you disturbed the ground connection? Or by installing new hangars or insulators you insulated the thing too good?  First step would be to unhook the wire and see which way the gauge goes. It should either go all the way up or down.  Next ground the wire and it should go all the way the opposite way. This will confirm that the gauge works and the wire is good.  If full is the state it goes to when unhooked I would go after the ground issue.  It could be something like the gasket in the sending unit is keeping the unit from grounding to the tank.  In some cases I have seen people clamp a ground wire around the outlet line with a hose clamp.  Not pretty but it works. 

[PHIL WHYTE CLC 14192]

I agree, I fitted a seperate ground wire to one of the screws that attach the sending unit to the tank on my 54. If you are getting a reading sometimes and it's showing full at other times it does point to an intermittant ground.
Phil

[The Tassie Devil(le)]

G'day Bill,

I am with TJH and Phil.

Get a good ground.  Sender Screw to Body.

Bruce.

[Bill Balkie 24172]

Hello TJH,
  Thanks so much for your help , come to think of it I Painted my tank and also the  two straps that hold the tank in place .  I will run a good solid ground wire over the weekend and let you know how i make out . Thanks again Bill

I dont know anything about a 57 but in general I would assume that that vintage would only have one wire to the sending unit so grounds become important.  Perhaps when you had the tank out you disturbed the ground connection? Or by installing new hangars or insulators you insulated the thing too good?  First step would be to unhook the wire and see which way the gauge goes. It should either go all the way up or down.  Next ground the wire and it should go all the way the opposite way. This will confirm that the gauge works and the wire is good.  If full is the state it goes to when unhooked I would go after the ground issue.  It could be something like the gasket in the sending unit is keeping the unit from grounding to the tank.  In some cases I have seen people clamp a ground wire around the outlet line with a hose clamp.  Not pretty but it works. 

[Bill Balkie 24172]

Thanks lou , i will give it a try .  Bill

Here's a good link for ya, it's for a Chevy but the principals are the same.

http://www.classicchevy.com/assets/pdf/29-92.pdf?

Lou 

[John Morris #23947]

I had a gas guage do that. I took the sending unit out of the tank, a copper strap had seperated. We brazed it back on, reinstalled the unit and WHALLA!! Gas guage fixed.

[35-709]

I had a gas guage do that. I took the sending unit out of the tank, a copper strap had seperated. We brazed it back on, reinstalled the unit and WHALLA!! Gas guage fixed.

This seems to be a relatively common occurrence, I have seen this same type of failure in 2 '66 Cadillacs. 

[Glen]

I had a gas guage do that. I took the sending unit out of the tank, a copper strap had seperated. We brazed it back on, reinstalled the unit and WHALLA!! Gas guage fixed.

This seems to be a relatively common occurrence, I have seen this same type of failure in 2 '66 Cadillacs. 

Does that copper strap flex when the float goes up and down?  If it does a better fix might be to solder a small braided strap in it’s place.  Just a thought.

Glen

[The Tassie Devil(le)]

Does that copper strap flex when the float goes up and down?  If it does a better fix might be to solder a small braided strap in it’s place.  Just a thought.     Glen   

G'day Glen,

No, the Copper strap doesn't move at all, as it is attached to the cover at the terminal and the Rheostat frame.   And isolated at both ends.

I personally have never seen that strap break.

Why they use a Strap, I am not sure, but there has to be a very good reason.

Bruce.

[35-709]

On one of the ones I had experience with the copper piece was almost completely gone.  Possibly the gasoline sloshing back and forth at first flexes it a little and over time it flexes more and more until it breaks off.  OR, something in the gas gradually eats it away.

[Bill Balkie 24172]

Hello ,
 thanks for all your help . I added a ground wire to one of the mounting screws on the sender and gage woek fine now . Thank to everyone .