I installed an OEM Harley oil temp gauge on my '93 FLSTC and I have the sender fitting positioned just before the oil cooler. The gauge markings are 120° to 350° but even when the motor is up to operating temp the gauge needle never moves. (?)

I know the gauge has power and is grounded because the light is on. I know the sender has power because I checked it at the plug. I know the gauge and sender are working because I removed the sender from the fitting and placed in boiling water and the gauge went up to almost 200°.

So, thinking that maybe the sender being on top of the T-fitting wasn't making good contact with oil passing through the fitting so I rotated the T so that the sender is now facing down. Now the oil is passing right over the sender probe and still now movement on the gauge needle. I know there's oil flowing through the fitting and into the cooler because the cooler is getting hot so what else could I be missing here???

 

Pictures might help since the '93 Heritage never came with an OEM oil temp gauge and the only one I know of that you can get from harley plugs into the oil bag.

 

Yeah, mine is in the plug in the bottom of the oil tank. I think the most it has ever recorded with the new filter (160F thermostat) is like 175, and that's at 80MPH pulling a trailer to Sturgis. I prefer a 180F thermostat, but that's what this cooler came with. Usually reads way low.

Anyway, if you put it in boiling water, it should have read 212F, not below 200. So there's a discrepancy there as well. Yeah, some pics would be helpful. Is the sensor more or less shielded from air flow? If the sensor is being cooled by the air, that could effect the readings too.

 

Why do you want to worry yourself about the temperature of the oil coming out of the motor? Wouldn't it be more important to know the temp of the oil in the tank before it goes into the motor? We all know what a proper AFR does to the engine temp wise, so if that's set properly why create more concerns?

 

Solutions to problems that don't exist. Chuck that defective probe in the garbage. What will you buy next? A digital oil pressure gauge? You'll likely rear end somebody starting at that voodoo gauge too.
Ignorance is bliss! Just look at my life. Lol
Good luck, OP.
Tom

 

like the good doctor said - the bottom of the oil tank

it needs to be in the big puddle to read whats in it

 

Genuine Harley-Davidson Original Equipment Manufactured for or by Harley-Davidson for use on its products. Granted the 1.5" Micro gauges are obsolete as are the bracket and the mount but all pieces are NOS.

If I walked into a dealership and had them bolt on a few parts out of their catalog I wouldn't consider that as having something "different" or unique. I've been tracking down this stuff for almost a year and I still need one more item. If it was easy it wouldn't be worth the time.



Actually I don't care about the temperature of the oil in the bag. If I did I would have jut shoved in one of those thermo dipsticks. Nah that's too easy. I already know that the oil in the tank is 30° to 40° cooler than when it came out of the engine because it's been through the cooler. I want to know how hot it's getting when it's in the engine. I'm not really worried, I just have a thing for gauges.

 

Actually I'm looking for 1.5" Micro Volt Gauge, #74507-04 to fill that third hole.

 

I boiled the water in a coffee mug and I'm sure I lost a few degrees going from the kitchen out to the shop. All I really was looking for was to see that the needle would move. I thought about the air flow thing so as you can see in pic #3 I have the sensor wrapped with a piece of rubber hose. Tomorrow I will make a rubber cover for the fitting itself.

 

Just because Harley made it doesn't make it OEM for your bike.
That thing was never Original Equipment Manufactured for a softail.

That said here comes the fun.
As both the Doc and John have said you need an oil bath to make that thing work so why not use a bigger connection to give the sending unit the bath it needs to work?

It's always a challenge getting parts to work on your bike that were never supposed to be there.
Trust me!!!!
Been there done that!!