Poor Results With Oil Cooler Door

RFazio · #1 12-13-2009, 05:34 AM

I installed my new Vans oil cooler door and went for my first flight in my 6 with it yesterday. It was in the 30s and 24F at altitude. The oil temp got up to around 155F. I have the door in front of the cooler and the cooler is mounted to the back of my baffles. I had the door completely closed. I was not happy with the results. I'm looking for any fresh ideas on how to get my temps higher. Some fellow RVers suggest wrapping the entire cooler with some kind of insulation, thinking the outside of the unit is radiating heat. I also think the back side of the cooler being open to air rushing around behind the engine is part of the problem. I was thinking of totally block off the back side just to see what happens to the temps. Thanks in advance for any ideas.

DanH · #2 12-13-2009, 06:26 AM

Installing a 1/4 turn ball valve in one of the lines would be an interesting experiment.

L.Adamson · #3 12-13-2009, 07:48 AM

Quote:

Originally Posted by RFazio

I installed my new Vans oil cooler door and went for my first flight in my 6 with it yesterday. It was in the 30s and 24F at altitude. The oil temp got up to around 155F. I have the door in front of the cooler and the cooler is mounted to the back of my baffles. I had the door completely closed. I was not happy with the results. I'm looking for any fresh ideas on how to get my temps higher. Some fellow RVers suggest wrapping the entire cooler with some kind of insulation, thinking the outside of the unit is radiating heat. I also think the back side of the cooler being open to air rushing around behind the engine is part of the problem. I was thinking of totally block off the back side just to see what happens to the temps. Thanks in advance for any ideas.

Interesting, because my first flight with the cooler door & the same temps you're experiencing, gave me constant temps between 185-195 degrees in cruise, and up to 220 in a sustained climb with the shutters fully shut.. Did you install a washer or two between the cooler & shutter? If not, the shutter doors will bind, because the cooler fins push against the center of the shutter. In fact, I can operate the shutter from the cockpit, and the temps will easily go up & down.

edit: P.S. -- I put weather stripping between the washers to fill the gap.

L.Adamson ---- RV6A/ 0360/ Hartzell CS

L.Adamson · #4 12-13-2009, 07:50 AM

Quote:

Originally Posted by DanH

Installing a 1/4 turn ball valve in one of the lines would be an interesting experiment.

Larry Vetterman (the exhaust pipe maker) has something along those lines.

lostpilot28 · #5 12-13-2009, 09:59 AM

Hi Richard,
I mentioned this in the other post about the oil cooler shutter, but I would suggest you verify the other possible causes for low oil temps before proceeding. I had the exact same thing happen, with the same outside air temps as you (my oil reading was hitting 150 F max), then I discovered that my EFIS setup was wrong.

What kind of gauges are you using to read oil temp? Have you tested the sending unit, or replaced it? Possibly check the wiring, the oil pressure setting, and the location of your sender. The amount of oil in your sump can affect it (slightly), too.

DanH · #6 12-13-2009, 10:04 AM

Quote:

Originally Posted by L.Adamson

Larry Vetterman (the exhaust pipe maker) has something along those lines.

Yes. As I recall he removed the vernatherm, capped its mounting hole, then installed a 69436 spring and 62415 plunger under the 62417 plug. The addition of a ball valve in the oil cooler line (rigged for cockpit control) gives him authority over how much oil flows to the cooler, zero to full flow. Pump output with the valve closed merely pushes up the 62415 plunger and oil flows through the old vernatherm hole.

Smart stuff, with perhaps one possible caveat. Consider cruise flight in very cold conditions with the above valve closed. There is no oil flow within the cooler body but it is exposed to airflow. If the airflow is cold enough the oil may jell in the cooler. A subsequent attempt to restore oil flow through the cooler (by opening the valve) may not work.

True? Worth worrying about? I dunno.

Kevin Horton · #7 12-13-2009, 05:11 PM

It seems quite strange that the oil temperature was that low if the oil cooler door was completely closed. The first thing I would do is confirm that the door does completely close. The second thing I would do is pull the oil temperature sender and pop it in some boiling water to see what the reading is.

RFazio · #8 12-15-2009, 08:19 AM

I have no reason to doubt my oil temp gauge. In the summer my temps are right in the middle of the green, 180 to 195 or so. Last winter I had the cooler completely blocked with a thin sheet of aluminum. The temps were about the same as they are with the shutter. In the spring when we started getting warmer days my temps were going up. On a 70 degree day with the cooler blocked it started getting up into the highest range just over 200. But I like your idea of checking the temp gauge, this way I'll eliminate the possibility of the gauge just being off. Then I'll go from there. Thanks

jjconstant · #9 12-15-2009, 10:16 AM

Would wrapping the oil filter in some sort of insulation help? Could it be behaving like a big heat-sink?

Jeremy Constant
RV7A- prepping for first flight!

Steve Sampson · #10 12-15-2009, 11:47 AM

Richard, your experience is not unlike my own, with a -4. I still see pretty low oil temps but have rather given up fighting them. Partly the problem is I tend to run around on quite low power; perhaps 55%. You can see my experience here. A warmer day (44F on the ground and 33F at altitude), and I do also have a hole, perhaps the size of a dime, in the blanking plate.

But I do have the cooler and filter wrapped up in that firewall insulation stuff to stop the heat escaping. On a -4, my experience is not so atypical though.

Normally, to practice slow flying AND to get the oil temps up I slow right down - 60mph - for a few minutes, nose high, just before I enter the cct. It has an immediate effect on oil temp though I curtailed it before normal on the flight shown in the graph above. It peaked at 172F, but had settled after the climb at about 145F. With the nose high, even though the power is low I think the airflow through the engineo decreases dramatically, hence the temp rise. I can only assume that the pressure rises on the outlet significantly.

I am confident in the vernatherm and instrumentation because it behaved just like this last winter but in the hotest days of summer you could see clearly on the graphs the vernatherm doing its job at the right temp.

Perhaps one day I will get around to reducing the cowl exit, but I think it would have to be a variable mechanism.