Gas Gauge and Speedo Question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

MBurns326 · 03-30-2009, 06:11 PM

ok I really need some help here guys......

First My gas gauge and oil pressure gauge are not working. Strange thing is that they are both on the right side of the panel, but the gauges on the left side (temp and speedo) are working just fine....well see the bottom......What could cause just the two on the right side to quit working. The oil pressure is really important and I would like to get it back working.

Second my speedo has been off for....(well it's a 1971) probably 38 years. Bigger tires were put on it when my grandpa bought it new. It's probably 25 miles per hour too fast, and as a result it is putting miles on twice as fast as it's supposed to. How can I fix that? Do I need a new cable or what?

THANKS!!!!

eightbanger · 03-30-2009, 06:30 PM

Can't ofer any help with the Gauges, but you will probably need one of these.. http://www.classicparts.com/1963-78-...o/91-932/...to sort out your speedo reading.

**mr48chev** · 03-30-2009, 06:35 PM

On the gas and oil pressure you have to check the circuits starting at the senders.

On the speedometer there are a couple of ways to go.

You can change the speedometer drive gears in the back of the trans to correct the reading or you can get a box that you can calibrate to correct the reading. That connects to the speedometer drive on the trans and the cable connects to it.

This site has some pretty good info
http://www.transmissioncenter.net/sp...FQEziQod3SGNeQ

You should be able to get the correct speedometer drive gears from your dealers parts counter or from a transmission shop that has a real good parts room though. You just have to know exactly what to ask for.

These days the simplest way to tell exactly how far the speedometer is off or how accurate it is, is to take a GPS and make a run down the highway at a steady speed and get a comparison. On road trips I use my GPS as a speedometer, I have a handheld unit that I use on the boat and it is pretty handy for speedometer calibration work.

68gmsee · 03-30-2009, 06:45 PM

Quote:

Originally Posted by MBurns326

ok I really need some help here guys......

First My gas gauge and oil pressure gauge are not working..........

The gas guage could be something as simple as the sending unit. One way to check is to ground out the single wire on you gas tank and see if the needle moves.

On the oil gauge, I'd first make sure that your are in fact pushing oil through the copper tubing. Sometimes they get kinked or clogged up.

03-30-2009, 06:11 PM	#1
MBurns326 Registered User Join Date: Nov 2008 Location: Macon, GA Posts: 20	Gas Gauge and Speedo Question ok I really need some help here guys...... First My gas gauge and oil pressure gauge are not working. Strange thing is that they are both on the right side of the panel, but the gauges on the left side (temp and speedo) are working just fine....well see the bottom......What could cause just the two on the right side to quit working. The oil pressure is really important and I would like to get it back working. Second my speedo has been off for....(well it's a 1971) probably 38 years. Bigger tires were put on it when my grandpa bought it new. It's probably 25 miles per hour too fast, and as a result it is putting miles on twice as fast as it's supposed to. How can I fix that? Do I need a new cable or what? THANKS!!!! __________________ Camouflage 1971 Chevrolet C/20 2WD

03-30-2009, 06:30 PM	#2
eightbanger 454 MAKES IT ROAR Join Date: Jan 2008 Location: Essex, U.K Posts: 2,701	Re: Gas Gauge and Speedo Question Can't ofer any help with the Gauges, but you will probably need one of these.. http://www.classicparts.com/1963-78-...o/91-932/...to sort out your speedo reading. __________________ Nigel. An American living in a British body. 1971 Chevy Cheyenne 10 454 "In a time of universal deceit, telling the truth becomes a revolutionary act." - George Orwell "When injustice becomes law, resistance becomes duty" - Thomas Jefferson No more pain. 03.12.60 -- 12.28.10 http://www.youtube.com/Eightbanger

03-30-2009, 06:35 PM	#3
mr48chev Registered User Join Date: Jul 2007 Location: Toppenish, WA Posts: 15,740	Re: Gas Gauge and Speedo Question On the gas and oil pressure you have to check the circuits starting at the senders. On the speedometer there are a couple of ways to go. You can change the speedometer drive gears in the back of the trans to correct the reading or you can get a box that you can calibrate to correct the reading. That connects to the speedometer drive on the trans and the cable connects to it. This site has some pretty good info http://www.transmissioncenter.net/sp...FQEziQod3SGNeQ You should be able to get the correct speedometer drive gears from your dealers parts counter or from a transmission shop that has a real good parts room though. You just have to know exactly what to ask for. These days the simplest way to tell exactly how far the speedometer is off or how accurate it is, is to take a GPS and make a run down the highway at a steady speed and get a comparison. On road trips I use my GPS as a speedometer, I have a handheld unit that I use on the boat and it is pretty handy for speedometer calibration work. Last edited by mr48chev; 03-30-2009 at 06:40 PM.



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