question on used vac gauge dial/needle position

[steveo3002]

i got this older snap on vac gauge that id like to move on , i notice the needle is a hair outside the "blue" zone

would you consider this an issue ? id like to sell it but wouldnt like to mislead anyone /sell cr@p

 

[bob15]

Test it. That gauge also does pressure, so it can be tested both ways

 

[steveo3002]

it works both ways ive used it

i dont have another known accurate tester to compare it with...all im asking is the needle resting where it ought to ?

 

[RTM]

No, unless you made some tool purchases that really ****, that should be at 0 when not connected. Not sure it matters, haven’t paid attention to the scales on mine in 35 years.

 

[engineer2]

On some gauges you can simply pull the needle off and put it back on in the correct position.
On other gauges you need a needle puller to avoid damaging the internal mechanism.
On some more expensive gauges there may be a zero adjustment.
If you reset the needle, you still need to check it against a known accurate gauge

 

[fsae0607]

Hook it up to a known good Mityvac and compare the vacuum readings. If it's off, you'll know the offset.

Same with pressure. Borrow someone's good fuel pressure gauge, find a test vehicle, hook them up with a tee fitting and compare readings.

 

[ttpete]

You'll never have absolute accuracy with that gauge, and for its intended use, ballpark accuracy is all that's needed. The fact that the zero mark is so wide confirms this.

 

[2ndGearRubber]

Hook it up to a known good Mityvac and compare the vacuum readings. If it's off, you'll know the offset.

Same with pressure. Borrow someone's good fuel pressure gauge, find a test vehicle, hook them up with a tee fitting and compare readings.

Carburated test vehicle.

Do not hook that up to an EFI vehicle. 100kpa is about 1 atmosphere, or 15psi. That gauge isnt meant to see 60psi.

Compare the gauge to a mity vac or another gauge. Some do have manual zero adjustment inside, depends.