Oil temp gauge

[casaleenie]

Need a quick lesson on how a oil temp gauge works...
SW oil temp gauge. I see the wire from the top of the remote oil filter and it goes into the gauge... How is the temp computed or registered?
The temp gauge has never worked and need to get it up and running, so to speak....<img src=images/icon_speech_duh.gif border=0 width=23 height=15 alt=Insert Speech Icon: Duh!>

AL

[pgermond]

H-m-m-m-m, mine goes from the gauge (Autometer) into the top driver-side of my Canton oil pan. Seems to work fine (although I haven't fiddle with yet to determine the accuracy). Guess, that's not much help for your set up. Sorry

Phil

427 Roadster, #4279436
Southern Automotive FE
3:31 and Toploader

Roseville (N.Cal)

[Brent]

The sending unit is a one wire unit meaning that it recieves "ground" from whatever it is screwed into. If the remote filter is not mounted to a grounded surface or if the sending unit was heavily taped or doped on the threads it may not be getting a ground and it will not work.
Hook up a test light to 12V positive on the car and touch the ground side of the light to the remote filter housing. If it lights then touch the base of the sending unit to see if it is grounded to the remote filter mount. If it is then you can look for something else in the sending unit or the gauge itself.

Easy stuff first

Brent

[Jim Harding]

Al,

You really want to know how it works?????

The sending unit is a variable resistor that changes its value as the temperature changes.

In electrical circuits, there is a law that is known as ohm's law. Simply stated, one amp of current will flow in a circuit when one volt of 'pressure' is applied to one ohm of resistance. Current is equal the the voltage divided by the resistance. Voltage is equal to the current times the resistance. And resistance is equal to the voltage divided by the current.

The gauge on the dash is the instrument that measures the current in the circuit. The constant (or near constant) voltage is supplied by the battery. The sender changes its resistance in relation to the temperature of the oil. As the resistance changes, so does the current in the circuit, and the gauge is calibrated to indicate the temperature.

The principal is the same for the water temp and fuel gauge too.

Rather simple don't you think :-)

- Jim -

Jim Harding
La Plata, Maryland

1982 #3004

[casaleenie]

thanks, Phil, Brent, Jim,

That gives me a starting point... While we're at it... Just because it's easy in this forum, I'm wondering what the acceptable operating temp for the oil?

AL

[Jim Harding]

Al,

I've heard it said that the oil should get at least 160 degrees inorder to 'burn' off mositure and other bad stuff that finds its way into the oil. Don't know how accurate that statement is..... just repeating what others have said.

- Jim -

Jim Harding
La Plata, Maryland

1982 #3004

[clayfoushee]

Someone told me that the oil termperature should be roughly equivalent to the coolant temp.. The coolants registers between 150 at cruise to 190 at idle, with the fans running. I've never seen the oil temp. higher than 140.

Clay

Unique 9299, 427FE side oiler, top-loader (close), 3.31 rear

Annapolis, MD

[Brent]

Clay,

That may be true without an oil cooler. Especially one thats mounted out front the way ours are.

Brent

[clayfoushee]

Brent,

Yeah, forgot to mention the oil cooler, but I agree. I'm sure that's why the oil temp runs a bit cooler.

Clay

Unique 9299, 427FE side oiler, top-loader (close), 3.31 rear

Annapolis, MD

[Jim Harding]

Don't have a cooler in my car, and the temp probe is mounted low in the 8 qt pan. When sitting still, the oil temp will run about the same as the water temp, or anywhere from 180 to 190. Going down the road, with air moving across the pan, the temp goes down anywhere from 10 to 20 degrees lower than the water.

And where is your temp probe located? Before or after the cooler. If after it, then you probably have heated up the oil enough to cook off any water in the oil.

- Jim-

Jim Harding
La Plata, Maryland

1982 #3004

[pgermond]

I've got an oil cooler - temp around 120-140 this time of year.

Phil

427 Roadster, #4279436
Southern Automotive FE
3:31 and Toploader

Roseville (N.Cal)

[casaleenie]

Jim,
Temp probe is located on top of filter/ Car has an oil cooler...Was advised by previous owner that the gauge never worked...

AL

[GeorgiaSnake]

Al give me an hour or so to confirm a few things and I'll give you the poop.

Randy

Unique 289 FIA
Southern Automotive 396
Team III 16's
Brilliant Silver

[Okiesnake]

I am going to add an oil thermostat. In actuality, most of our cars probably don't even need an oil cooler on the street. However, they sure look good!
An engine has an operating range where lubrication and fuel mixtures are optimum. Running with the oil too cool will allow water and fuel condensates to build up, plus oil flow will be reduced to many critical areas.
In the wintertime, I place a piece of aluminum over the oil cooler, but a thermostat is really the way to go. I think I'll go with the Mocal OT2 ( see http://www.batinc.net/thermos.htm )for $95.00.

[clayfoushee]

Trent,

Where does that oil thermostat mount. I'm feeling like I need to warm that oil up a bit. I sure as hell don't need "oil flow reduced to many critical areas" in a BB FE.

Clay

Unique 9299, 427FE side oiler, top-loader (close), 3.31 rear

Annapolis, MD

[Okiesnake]

It goes between the oil filter and the oil cooler.

[clayfoushee]

So, basically, you have to cut those braided steel hoses and put 4 new fittings on which attach to the thermostat?

Clay

Unique 9299, 427FE side oiler, top-loader (close), 3.31 rear

Annapolis, MD

[casaleenie]

You mean those $425. oil hoses????

AL

[clayfoushee]

Al, that's what I was worried about. Hopefully there are fittings that come with the unit that would allow you to take the hoses off at the oil filter and route the thermo. between the outlet and inlet hoses.

Clay

Unique 9299, 427FE side oiler, top-loader (close), 3.31 rear

Annapolis, MD

[Okiesnake]

The hoses aren't that hard to cut. BTW, Much cheaper than a 427FE side oiler!