oil temp gauge

[carrooth]

Ok. I'm back to troubleshooting my oil temp gauge. The needle will not move. I have checked the sender and it seems to work properly. I have checked black and green wire from sender to gauge for continuity, no problems. I have grounded spade connector nothing. I have disconnected green and black wire nothing. Something else I just realized, the gauge light also does not work. Oil pressure does work.

I guess I'm just hoping its not the gauge and I'm missing something. Any ideas are much appreciated.

Jay

[carrooth]

ok today I checked the gauge backlight and it was burned out. So, that has nothing to do with it. Checked the "+" wire, it has good voltage. When I check resistance on sender to ground the multimeter reads 011 (whatever that means).

Thanks for any ideas

[spuggy]

The oil temp gauge is a voltmeter. If you ground the terminal which should connect to the sender and the gauge has a 12V feed , it should peg high.

It sounds likely to me that the gauge is broken, as you say there's continuity on the sender wire, and grounding the sender spade does nothing.

You could check this with a spare one, or get yours fixed. It might be as simple as something jamming the needle/movement inside, or a broken internal connection (e.g. to a winding).

I'd take it out, remove the gauge from the clock and stick a few volts across it and make sure the needle moves... But that's just me.

[carrooth]

Thanks for the reply spuggy. So what your saying is take the temp gauge out of the dash, hook up 12v to the "+" and ground the "G" and see if it does something different on the bench. The car sat for at least 7 years and I've spent a couple slowly bringing her back to life. I was wondering if its like some of the joints in my body are getting, once I sit for awhile they don't want to move anymore.

If I bench test the gauge, can I just hook up + & - on a spare 12v battery to + and G on back of gauge? Or will that fry my gauge, if its not already.

[spuggy]

Originally Posted by carrooth

Thanks for the reply spuggy. So what your saying is take the temp gauge out of the dash, hook up 12v to the "+" and ground the "G" and see if it does something different on the bench. The car sat for at least 7 years and I've spent a couple slowly bringing her back to life. I was wondering if its like some of the joints in my body are getting, once I sit for awhile they don't want to move anymore.

Well, firstly I'd be tempted to note that the oil pressure gauge in the same clock is also a simple meter, just like the oil temp one. I'd be tempted to swap over the sender connections and observe what happens when I turned the key on...

If nothing very interesting came out of that (like the fault stayed with the temp meter), I'd next remove the round gauge from the car, drag it somewhere clean and well lit, assemble a collection of eyeware ('coz I'm getting to be an old fart , boil the kettle, take the oil temp gauge out and eyeball it. Take your time.

If the gauge is connected internally and functional (like if it were mechanically jammed, say) you should be able to measure some resistance - not a lot, but *something* from the back connectors all the way through the meter windings and back to the other connector.

If there's continuity but no resistance whatsoever, even on the most sensitive range, there's a dead short somewhere.

If there's no continuity, there's a break. Hopefully it wouldn't be the wires connecting the windings, because they'd be extremely fiddly to solder...

The pressure gauge on the other side is just a simple meter too, (e.g. nothing fancy like the speedo or tach). Repeat your tests on that, and compare results, just to see what you should get on the other side/demonstrate the difference.

If I bench test the gauge, can I just hook up + & - on a spare 12v battery to + and G on back of gauge? Or will that fry my gauge, if its not already.

No, that shouldn't harm it by itself, it's what is going on in the car. If it were going to fry it because of some fault, that ship already sailed a long time ago when the magic smoke escaped...

That said, connecting it to something that can turn the engine over and arc weld screwdrivers to a chassis is a lot more juice than you need for the job at hand, would you not think?

You only need the needle to move to demonstrate that the meter "works" for some value of "works".

A PP3 9v battery should be fine for that, or a 0.5 Amp wall wart or something. Variable DC output bench power supply is what you really want, but not worth buying or building one for this...

You likely won't get full-scale deflection with 9v, but I think your problem is more fundamental than that - like a jammed mechanism, broken/melted winding or a wire dropped off somewhere. Unfortunately, if it's the last, it's likely to be the thinnest, most delicate wires...

Repeat your PP3 test with the pressure gauge (which I presume works), just to see what you should get on the other side/demonstrate the difference.

I'd say your mission at this point is to first eliminate a fault in the car and then prove the gauge broken, hopefully establishing what's wrong with it in the process.

Of course, it'll be something simple, obvious and readily fixable. We all live in hope, eh?

good luck!

[carrooth]

Thanks for the great tips. I'm going out of town for the weekend. I will try this next week and report my findings.

Thanks again