Oil level sender

bahama68 · Post by **bahama68** » Mon Sep 18, 2006 1:08 pm

On start up the needle on my oil level gauge flicks straight off the scale and stays there (it occasionally flicks back down off the scale but not very often).

I presume either the sender or the gauge in knackered?

Where is the sender located and is changing it something I coould do myself?

Thanks

John.

Gary71 · Post by **Gary71** » Mon Sep 18, 2006 1:23 pm

Hi John, Your sender is in the tank itself. I'm not familiar with the tank on the '68 as mine is a '72 with it's obscure tank location, but I think the sender is the same.

Basically it's a little float and a sliding potentiometer. I'd check the wiring first before getting dirty and pulling the sender out. A flickering gauge sounds like a dodgy earth rather than a failed sensor. Mud can get thrown all over the tank off the wheel and the terminals on the sender may be corroded. Your symptoms may also be a short caused by the wiring having rubbed through on the bodywork somewhere.

Not much help I know

but hope you get it fixed!

Barry · Post by **Barry** » Mon Sep 18, 2006 1:53 pm

I seem to remember that these gauges work by having a full 12v in all of the time, and the earth (-ve) side of the instrument going back down to earth via the potentiometer/resistor at the sender.

Therefore if a gauge didn't do anything, it could be no voltage in, or open circuit back to the sender, or poor sender earth.

In this case though, it sounds as though the 12v earth side of the instrument is getting back to earth without having to negotiate the sender's resistance. Therefore I would disconnect the earth side of the instrument, and the connector on the sender. Put an ohm meter between the instrument negative (earth) WIRE (the one that heads off to the sender) and a good earth on the body: you should get open circuit (nothing showing). If there's any earth showing (i.e the wiring is shorting to the body), that's your problem. You could confirm by running a test wire from the instrument earth terminal all the way round the outside of the car, and down to the sender: in theory the gauge should now work.

If the wire hasn't shorted, just try the meter from the sender on the oil tank (i.e. the terminal) down to earth: you should have some sort of resistance (like 100's or 1000's of ohms). If it shows the same sort of reading that you get just by touching the meter's leads together (0-3 ohms), you've got a short within the sender, or at least between the sender terminal and the oil tank body.

HTH and makes some sense

.

Alan @ CanfordClassics · Mon Sep 18, 2006 1:57 pm

Hi John,

Gary is right check the wiring first. If you look up at the tank (from under the rear bumper) you will see the two wires that connect to the sender. One is an earth and the other power to the sender. Check these first, do you have a voltmeter? Once you have this info you can then start to work out where the problem is. I have taken the sender out before with the tank in place but if required it might be a good time to take the tank out and give it a good clean up.

Let us know how you get on

Alan

Barry · Post by **Barry** » Mon Sep 18, 2006 2:01 pm

Forgot to say: I had exactly this when I first did the car: the gauges just banged straight up onto the stops. Unfortunately I managed to give my 911 manual away with the last car, so havn't got a wiring diagram to check against to be sure of the above, but the basic principles will hold.

Has anything changed that may have induced this? Under dash work, dash terminal plug removed and replaced, radio installed, cleaning around the oil tank?

bahama68 · Post by **bahama68** » Mon Sep 18, 2006 2:10 pm

Cheers guys.

It's been like it since I bought my car but has only just started to bother me. I'll get the voltmeter out tomorrow, check it and let you know what happens.

Sounds like I'll need to get to the back of the gauge to test the earth. Is it easiest to do this through the front lugguage compartment or by removing the gauge from the dash.

John

Barry · Post by **Barry** » Mon Sep 18, 2006 2:21 pm

Probably easiest just pulling the gauge fowards in the dash: all of my dealing have been with the later (2.4) cars where the gauges are held in with rubber grommets: you just wiggle them out towards yourself.

I'm not sure, but think you might have securing clamps on the back of the gauges? Even so still probably easier to pull the gauge out: worth a quick look on the other side of the dash though, just in case it's easier that way.

Actually that was a long way of saying I don't know wasn't it

. I'm going now ...

bahama68 · Post by **bahama68** » Mon Sep 18, 2006 2:29 pm

Barry, it's really helpful to know that all I need to do to get to the back of the gauge is to undo the clamp rather than wiggle it, like I would have had to do if I owed a later model car, for example a 73 E or a 69L, or even a 2.7RS, which would have been nice to own, if I could have afforded it, although in the present market, with prices inflating at such a rate, it's highly unlikely.

Or thanks.

bahama68 · Post by **bahama68** » Mon Sep 18, 2006 5:24 pm

Barry, by the way, my classic car restoration night course finally begins tonight. So it won't be long until I'm taking my first tentative steps into the world of welding and painting. Disturbingly, as I don't own a house or a garage, I already have perspective projects flying around in my head.

Barry · Post by **Barry** » Mon Sep 18, 2006 5:35 pm

Hey, that's great: I'd forgotten about this. Seems so long ago that we talked about the course.

Hope it goes well, I'd be very interested to know how you get on.

Alan @ CanfordClassics · Mon Sep 18, 2006 5:48 pm

Hi John,

A 68 car like yours will have 2 clamps holding the guages in. To save you pulling the guage, just check to see if you are getting 12 v on the feed wire to the sender, if so chances are the guage is ok. 9 times out of ten its a earth problem around the sender or dodgy connections in the circular loom plug which is in the r/h front corner of the engine bay (as you look at it).

Cheers

Alan

bahama68 · Post by **bahama68** » Tue Sep 19, 2006 11:12 am

Thanks Alan, I'll try to have a look at it tonight.

Barry - The course went well. The workshop seems to have every single tool under the sun, all I need to do know is learn how to use them. Had my first go at Mig welding and gas (oxyacetelyne?) welding

A few more months, no years, of practice may be in order. Very enjoyable though. They also have two spray booths, one for primer, one for top coat, which is great as learning to paint is something I'm really interested in. All in all first impressions are very good.

John.

Barry · Post by **Barry** » Tue Sep 19, 2006 9:48 pm

Crumbs: sounds like it's the real deal!

Hope it continues well, sounds like you're in good hands

.