How hot is it

[niner11]

Before I spend any big money on trying to get my sc to run cooler I bought a digital temp probe. The question is how close is the oil temp in the tank to what the sender would be reading on the chain cover.
I'm on the road so I don't have anything to look at right now. Just wondering if the engine oil cooler cools the oil before it goes to the tank or just before it returns to engine. The car has a factory loop also. Trying to see if the gauge in the dash is accurate. Thanks, Chuck

[Randy Webb]

I dunno, but there are two considerations -- one is accuracy and the other is that the oil as a result of the design may be a different temp in the two locations.

When the oil flow is faster it will be more likely to be the same temp. at both places, IF faster oil velocity is not correlated with heating and cooling of the oil. BUT it probably is correlated - higher car speeds will cool the oil and higher engine speeds or load (related to higher car speeds) will heat the oil - both will in turn increase flow velocity.

This why people get engineering degrees and PhDs in this stuff....

I think the thing for you to do is to test the temp sensor it self and see if it is accurate. Remove it and do that. That is the simple way to solve the problem.

[RoninLB]

Originally posted by niner11
Trying to see if the gauge in the dash is accurate. Thanks, Chuck

if you have the numerical reading on the ga ?
set up a test in boiling water for sender and ga

[niner11]

Pretty sure its the gauge but I thought I'd get a few opinions about the differing oil temps taken from the tank or sender locations. The sender I have is the correct one and was replaced about a month ago but my gauges have been converted to white background by the PO. I have been told that the tach is off and I know that the fuel level is incorrect. Would not be a long stretch to think that the needle pointer on the oil temp was installed incorrectly as well

[Grady Clay]

niner11,

First a question: What is your new temp sensor like? Is it a flat piece? Will it go under a nut or screw? Can you get other sensors?


OK, you have two projects:
First is to calibrate your dash temp instrument.
Second is to determine the functioning of your oil system.


Find a way to attach your new temp sensor where it will read the oil temperature as close to the factory sender as is reasonable. You want to be measuring the same temperature of oil with both systems.
Make a blank (removable) clear decal for your dash instrument. Over the course of a few days, mark the decal with your digital readings and keep a log of corresponding digital measurements and your analog instrument indications.
You now have a calibrated temp gauge.



The functioning of your external oil system is more adventuresome. I think the two most important things are confirming the proper functioning of the external thermostat and the effectiveness of your front cooler.

I would do the front cooler measurements first. You want to measure the temperature of the front cooler oil pipes, both going to the cooler and the return. I would do the measurements at about the rear of the passenger door, just where the pipes turn and go forward under the door. You do not want to do the measurements right at the thermostat.
If you have a sensor that can be safely squashed, the screw-type hose clamp method works great. Fit a clamp loosely around each pipe. Tale an old top from an aerosol spray can and cut it into two strips about 10 mm X 30 mm. Clean the oil pipe with some Scotch Brite, a small area only where you plan to put the sensor will do.
Put the sensor next to the oil pipe, cover with the plastic, slide the clamp over both, and tighten the clamp. The plastic is to insulate the sensor from the clamp and the outside air otherwise your measurements will be low. A little grease between the sensor and pipe will improve the heat contact also.

Drive the 911 in a situation where you are sure it will get as hot as it can. Hot day, A/C on, fast, up hill, etc. Keep track so you can repeat best possible. You want to record the dash instrument indication, the digital readout, outside air temperature, and time-of-day. Have a passenger log the data, say every 10 seconds.

Change the location of the sensor to the other oil pipe and repeat the experiment. You can now see why having multiple sensors is a big benefit.

To do a very through study, I would use a data-logger and five sensors. The sensors would measure temperature at; 1) the oil coming out of the engine, 2) oil going to the front cooler, 3) oil returning from the cooler, 4) oil in the sump tank, and 5) oil at the factory temp sender.

With a single sensor, some patience and a good helper, you can get reasonably reliable data. Like any experiment, you want to repeat it several times to confirm your measurements.

You are not competing with NASA. All you want to do is determine the proper functioning of your external thermostat and have a base-line to go by if you change your front cooler.

Best,
Grady

[RoninLB]

Originally posted by Grady Clay
You are not competing with NASA.

maybe not.. but it probably could w/ your info.

[niner11]

Grady, thats good stuff, thanks. I'll rig up the digital probe to several different points on the oil system when I get home. The trick will be to find a location that is representative of the factory oil temp sender. Have a few threaded "caps" that screw into the chain cover housing left over from the tensioner update kit. Might be possible to drill the center of one and rig a probe into it for an accurate reading. Just for grins I got a temp or 230f at the tank after seeing the oil temp gauge at its peak in hotlanta.

Unless I find a problem with the gauge or oil cooling system that shows the car is running cooler than I suspect an Elephant carrera style cooler is in my future. Right now it only has he "trombone" factory set up. Chuck