Author Topic: Oil Gauge problem (Read 4405 times)

Smokey Eddy · « **on:** April 21, 2009, 02:22:18 am »

I don't know what that sound is in the video. It sounds like my engine running on my phone but on photobucket the video looks god awful and sounds hilarious.

All I'm doing is dimming the dash lights and the needle drops to a more normal reading.
I HAD solid core wire on it temporarily and i just changed it to nice good quality stuff. But it still does it! I thought it was an induction in the wire from the solid core being so close to the wires that give the bulbs power. but no.

Is this a problem within the gauge? or am I just a moron... someone please point out my blunder!

The back of the gauge ....

There are numbers on the back there... could that be some sort of calibration?
I bought the gauge from prothe for like 25$. Anyone experienced this issue with oil temp gauges before?

regcheeseman · « **Reply #1 on:** April 21, 2009, 04:27:37 am »

Can't watch vid at work but....

Gauge needs a solid 12v to read correctly, if it is taking it's supply from the dash illumination circuit and you are dimming that circuit then the reading will change according to the voltage applied.

Op-Ivy · « **Reply #2 on:** April 21, 2009, 10:15:01 am »

Reg is right. You might have it wired the wrong way.

I have the accessory wire on my stereo hooked up to illumination so I can turn my light switch on while parked and listen to music without having to turn all the accessories on or cycle the glowplugs.

If I turn the dimmer switch down too much the cd player stops playing. If I turn it down a bit more it shuts off.

Might be the same thing.

Smokey Eddy · « **Reply #3 on:** April 21, 2009, 02:13:26 pm »

Good idea.

But the gauge reads excessively high. when i dim the lights it reads a more normal temperature. 180-190...

Do you guys run an oil temp of like 200F

If i kill the power to the lights the gauge stops reading.
There are only three wires out the back. ground, red and the feed from the sender.

I'm thinking there should be a ground, a white for the lights, red for 12v and input.

Op-Ivy · « **Reply #4 on:** April 21, 2009, 02:57:34 pm »

The gauge should be configured to have a constant 12v in. It will naturally lower the reading as you decrease the voltage because it is meant to always have 12v. However it will most likely have an internal regulator that keeps the incoming voltage under 12v. So theoretically speaking, when the car is on and charging, you should be able to lower the dimmer switch to 12v and the gauge will have the same reading until you go below 12v.

So unless the gauge itself is off, the reading it is giving you should be accurate. Always good to find a buddy with a different gauge and see what the reading is.

Edit: Also, if it only has 2 wires for current, the gauge probably uses the constant 12v for the lights too.

Vincent Waldon · « **Reply #5 on:** April 21, 2009, 03:10:43 pm »

My oil temp at the filter flange is 100-110C (212-230F) on the highway...and the gauge's redline is at 150C (it's a standard VDO oil temp gauge from a Cabby).

If you think about it... on our cars with the oil/water intercooler it's reasonable for the oil to reach water temperatures... and beyond.

To help you with your wiring problem... you've got three wires:

- a good ground ?
- a good feed to the sender, which is also grounded well ?
- the red power feed going to a good source of constant voltage that's hot when the key is on?

If your red wire goes to a source of power that dims with the dash lights...
:wink:

As an aside, the cheap gauges usually share the power lead with the lights lead, making it impossible for you to dim the lighting without impacting the calibration. They also rarely have an internal regulator, meaning that the reading will vary a bit due to the alternator output, loads on the battery, etc.

On the other hand, with a knife and a soldering iron you could probably modify the lighting inside the gauge to have its own supply.

Smokey Eddy · « **Reply #6 on:** April 21, 2009, 08:59:22 pm »

Okay, so i need to wire that gauge separately away from my dimmer switch.

It is definately NOT reading the correct oil otherwise my oil would have cooked....

Also, the dimming effects the needle on a power curve given the input (temp) from the sender.
meaning, at 140F the dimmer doesn't change the needle much but at 180F the dimmer going BRIGHTER will push the needle to the 210F+ mark.

I'm reading the temp at the head.

madmedix · « **Reply #7 on:** May 23, 2009, 07:08:13 pm »

The LM317T is your friend

. Picked up a whack of them (50) on eBay for $12 a couple of years ago. It's a nifty little variable voltage regulator that you can spec to 12 volts easily and it can deliver over an amp of current (Don't forget to heat sink it!). I put one of these bad boys in the back of my center console on a little wiring area I made; and another behind the "six pack" switch area to power switched relays, guages etc. Simply run a 10 guage wire through the firewall (fuse it!) and run it to your circuit in the center console (or wherever you choose). On the circuit's output, I wired it to a terminal strip (6 open screw terminals, all fused) and I just use a female spade connector any time I need another voltage tap at a regulated 12VDC. It's uptight & outta sight. No more fishing wires around the front of the car. The bonus is that you can run a second 10 guage line under the carpet into the trunk and run an amplifier or whatever back there without running a line under the car and punching a hole in the trunk area to get back inside. Here's a link to get you started: http://ourworld.compuserve.com/homepages/Bill_Bowden/page12.htm

Cheers,
Andy