oil temp in tank vs at sensor

[jwakil]

I'm trying to figure out if my temp sensor/gauge are measuring accurately. If I measure the oil temperature in my oil tank, I would imagine it should be a lot cooler than at the temp sensor on the engine, right? Anyone know approx temp delta expected? I guess the best measurement would be to take out the temp sensor and stick a thermocouple in the hole, right after engine shut down.

[Joe Bob]

nope....should be close.......

[DW SD]

The temp in the tank is cooler, as it has been through the oil cooler. I'd guess 5 to 10 degress different.

Best way to calibrate your gauge though is drop in a pan of boiling water. Extend the ground and the lead to the sensor and drop it in a bucket of boiling h20. will be right at 100C or 212F

Doug

[uwanna]

As shown by the chart below, the return hot oil from the tank travels thru the on engine oil cooler (via thermostat) before running thru the motor and bearings. (thus being heated again). The scavenge pump then returns the hot oil to the tank. Therefore, on a 911 without a front fender cooler, the returned oil in the tank will be very close to engine oil temp. If you have a front cooler, the oil in the tank will be close to engine temp till the Aux oil thermostat opens to the front cooler.

[jwakil]

Originally Posted by DW SD

The temp in the tank is cooler, as it has been through the oil cooler. I'd guess 5 to 10 degress different.

Best way to calibrate your gauge though is drop in a pan of boiling water. Extend the ground and the lead to the sensor and drop it in a bucket of boiling h20. will be right at 100C or 212F

Doug

I didn't think about the water method. Would the engine have to be on to test or would just turning key to ACC activate the guage?

[KTL]

Some racer or engine builders want to know the temp in the tank. For instance SmartRacing puts a bung in their front mounted oil tank to allow you to gather this temperature. But from another perspective, you want to know what your peak temperature is, which is at the source of the heat- the engine.

To check the delta from tank to engine you are correct. Just remove the oil tank cap and sticking your thermocouple in there. If you think the temp sender is inaccurate, yes you can simply dunk the sender in the boiling water with the key on and you'll get a reading.

[MBruns]

I like to see what the temp of the oil is before the cooler on race engines, not a bad idea to have a sender in the tank as well, it will show how effective the cooler is.

Mike Bruns JBRacing.com

[jwakil]

Well, today I attempted the sensor validation with a cooking thermometer and some heated oil. I put a wire extension on the sensor wire, and grounded the sensor housing with some jumper cables, that allowed me to dip the measuring end into the heated oil. Although its pretty hard to get precise with the guage that has no numbers on it, based of of the 90C (195F) and 120C (248F) lines I believe the guage was reading the peak temp fairly precisely. But what I did notice was that the response time, especially on cool down, was pretty slow. If I pulled out the sensor from the oil, it took quite a while for the guage to go down. Heating up was quicker (at least it seamed to me). Anyway, I think there might be times when the oil is cooling down and the guage is still reading high. I had noticed when I'm driving that once the temp reaches its peak during stop and go, it kind of stays there even when I get on the highway. Never the less I was hoping the sensor was reading higher temps period, which would have made me feel better. I've tried everything else to lower the temps with no success.