Oil Temperature Gauge

[jeff_hooper]

I've always liked an Oil Temperature gauge. It gives a much more realistic indication of genuine internal engine operating temperature. I remember years ago, being amazed how little Oil Temp you can have even though the Water Temp gauge has come up to a fully hot reading. I find it works very well for me at keeping my right foot from getting to heavy, too early on the loud pedal.

I have an Lotus OEM Oil Temperature gauge (S4 type) that I want to fit in the dash in place of the clock - pre facelift dash.

I though it would just be a matter of wiring it up taking an additional wire from the oil temp sensor in the sump plug. Didn't work for some reason... My guess is the the sender is of the wrong type/rating to work with this gauge?

I seem to recall reading that whilst the oil sensor feeds info direct to the ECU that information isn't used by the ECU for anything, in fact I think early V8's didn't have the sensor fitted - I may be wrong on these points. If this is right then I could simply disable the wire to the ECU and replace the sender with a type that will work with the S4 gauge?

Does anyone have any input on this or any suggestions for alternative options to get this type of oil temperature gauge working?

Jeff

Ps. Speaking of loud pedals I used to have an MG Metro (took it from 12 months old through 100,000 miles and into a scrap yard over 20 years later). That had a stick located between and slightly in front of the front seats - you could depress one of the pedals and move the stick about quiet easily. On most cars its called a gear lever and is part of the acceleration process. On my Metro however it seemed to be some sort of engine volume control - when I moved the stick about that's the only thing that ever happened! No change in acceleration just a change in engine volume.

Edited June 3, 2008 by jeff_hooper

[david hopwood]

The unit in the end of the sump plug on the V8's is a switch ,it is either open circuit or short circuit at the pre determined temprature,you need to replace it with a thermistor this will give a variable resistance in sympathy to changing temprature as most auto gauges are moving coil voltmeters with differently marked scales.Thermistors are usually refered to as PTC or NTC positive or negative temp coefficient ,positive will increase resistance as oil temp increases negative will decrease resistance as oil temp increases you will need a NTC type for your project.

Hope this helps.

cheers dave

[jeff_hooper]

Thanks Dave, that's great information fills in my lack or understanding and takes this little project forward for me many thanks.

Can anyone say if its okay or not to just leave the original oil temp connection from the sump plug sensor to the ECU to be disconnected?

Jeff

[david hopwood]

Hi Jeff,

Yes you could leave the plug to the ecm disconnected because under normal conditions the switch will be open circuit ,but if your oil was to overheat you would not get the flashing red telltale on the dash to alert you ,also the emc may be programmed to eventually cut fuel or ignition if the temp increases(not sure about this though)

Why not consider the use of a suitable tee peice feeding the oil to both the switch and your new thermistor?that way you won't loose any function.

cheers dave