Under Trunk Temp., Addition to Oil Cooler Thread. Options

[Olympic 914]

So on the Oil Cooler thread the suggestion was made to place a thermometer under the trunk to check the temps to determine possible difference for cooling efficiency.

I don't know if anyone had done this before. So I broke this off into a new thread for future reference.

One of the Oil Cooler threads

http://www.914world.com/bbs2/index.php?showtopic=347075

So yesterday I did this.

Using a Wifi endoscope taped to a magnetic tool holder with a thermometer.

Placed parallel to the Setrab oil cooler to sample the air temp without the fan blowing directly on the thermometer










And went for a drive. My GF rode along to monitor the temps and take notes.

The outside temp was 80 rising to 85 yesterday.

Idling in the driveway the temp rose to 125, after 2 miles of two lane roads 30mph it had dropped to 120.

at 4 miles stop and go it was still 120, Oil temp 200 CHT 340

onto a two lane road for 11 miles with speeds from 30-50 mph air temp was between 118 + 120 deg Oil temp 212 CHT 322

at this point I stopped for 2 minutes to mimic sitting at a long light or in traffic.
the air temp rose to 140 deg Oil temp 210 and CHT 337

Pulled onto 4 lane and accelerated up to 70 mph. After 1/2 mile the air temp had dropped to 125deg oil temp 209 and CHT at 370.

mostly level with some slight grades.

Turned around at 23 miles

Air temp holding at 125 deg Oil temp 213 CHT 330

The battery was low on the endoscope and I had turned it off on the way back, and when I turned it back on I discovered that the duct tape had loosened and I lost my thermometer.

My setup is a 2056 9590 cam Djet. , Oil cooler is Setrab 119 fanpack 180 deg oil thermostat and 190 deg sensor for the fan. Exhaust is SS HEs and a Triad muffler.

When running in normal summer heat the fan runs constantly.

If any one else decides to do this Please add your results here.

Tom

[GregAmy]

Test loop: my home is 5 minutes from I-91 in Middletown CT so I left the house and headed for the highway. Initial direction was southbound, which has a gradual decline to New Haven and Long Island Sound. Very light traffic.

As I started out I noticed something that surprised me: the bottom side of my cooling duct was baking. This duct extends downward between the transaxle and the right exhaust and ends roughly below the bottom of the heat exchanger. And it's close.

Recall that the oil cooler has a physical thermostat, which opens at around 180F. The fan does not come on until 220F. So until the thermostats kick in, these first two probes are roughly measuring actual air temperatures in between the heat exchanger and transaxle, and at the top of oil cooler near the trunk.

And it was baking.

It took a bit for the oil temp to come up to speed, but before the fan kicked on I was seeing nearly 200F at the bottom of that duct with 120F at the trunk:



The front under-trunk area and engine compartment wasn't too bad at that point:



Once the thermostat fully opened and the fan finally kicked on the temperatures inverted. What was surprising was how much higher the forward engine probe got:



Long story short, once I had been in highway cruise for about a half hour, everything pretty much stabilized. Oil temps were around 214F with the fan constantly on.



Here's the graphs for all four. You can distinctly see where the duct was baking until the fan kicked on, and how things stabilized. You can also pick out where I exited the highway and sat a bit at the light before reversing course.
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