Mopar Muscle Association UK

Probably the sender unit I dont trust those lekky ones, tried a new unit ?? or have a good old tube mechanical type

I didn't want to mention anything, just in case you'd changed the post after John had replied.

My first port of call would be to check the actual sender wire and make sure that the gauge isn't earthing, because I think I'm right in saying that, like the fuel gauge, if it's earthed it'll send the needle right over.

I bet Dave 999 would know, he's clever like that...

naa mines never gone wrong and is made by VDO (not a US supplier to Mopar in them days) so i know little about them but based on other guage fun ive had here is some stuff

there are a few things you can try

2 types of oil pressure sender

1) one wire:- 1 wire to the sender only . in which case the sender earths to the engine block through its variable resistance. and has 1 connection to it from the guage (the guage will have 2 wires)

2) 2 wire:- 12volts into sender on the first wire and a variable voltage out of the second contact up a wire to guage which earths through its pointer windings to the case/dash/carbody

i.e you will have a 2 wire guage with a 1 wire sender or a 1 wire sender with a 2 wire guage

what you do from here depends on what style guage you have

Ivor is probbaly correct

one of the wires will have blown around in the wind for 30 years and will have worn through. most likley up front where its hot windy and vibratey

disconnect sender

measure resistance between pins on it and the body as the engine is reved

one of them should make the meter change => sender ok

check back of guage

how many wires
what happens when disconnected
what happens when not earthed to dash pod

a 2 wire guage has a supply wire and a signal wire

a signal wire that is shorting will make the guage go to one extreme or the other

diconnect signal wire and instead earth the signal contact to the metal body via a graphite pencil the guage should move a bit if its ok as you have just replaced the direct short with the small resistance of a 15 cm chunk of graphite (use a resitor if you have one most people have a pencil)

1 wire gauge

body of guage is earth and must be connected via screws to dash pod which is connected to body of car.

in this case the guage is powerd by the feed from the sender if you disconnect the sender regardless of of if the wire to the guage is shorted or OK the guage should do absolutly nothing it has no way of getting any power to do anything i.e no movement at all when you switch on the ignition


PS any 3rd wire on a 2 wire guage or second on a 1 wire guage will be for a back light to the guage (this should be quite obvious as to what it is)

take out the bulb and use it to power the guage (with the/head lights/dash lamps on) if you suspect the guage power feed to be knacked.

remember there is nothing wrong with connecting up a small houshold battery with two wires

use the negative for earthing duty and ping each connector on the back of a guage with the positive. usually indicates if the guage is alive still and punts out such low current that you won't knack anything

the little oblong 9 volters from stuff like walky talkies and baby alarms are demon for this kind of thing


Dave

Dave you are a star, I knew you would know, I'm afraid I'm electronically dyslexic...I can't see the stuff going through the pipes.

If the gauge reads high even with the wire disconnected then the gauge wire is shorted to earth or the gauge is shot

as John says bin the electric and go mechanical

or fix the stock electrical one for looks and authenticality then fit a mechanical one for your own peace of mind

David get yourself down to Halfor*s & buy one off the shelf. Got one in my car & works a treat