IO360 High Oil Temps

[MarkW]

Seems like one of two things would happen.
Added airflow through new oil cooler exterior vent would add pressure to the exit increasing overall mass.
Or mass stays the same by reducing original inlet volume = higher CHT's.

[DanH]

Originally Posted by MarkW

Seems like one of two things would happen.
Added airflow through new oil cooler exterior vent would add pressure to the exit increasing overall mass.
Or mass stays the same by reducing original inlet volume = higher CHT's.

Exit is the throttle. Added inlet area would add pressure, but it's easily offset by shrinking exit area, which limits mass and increases velocity, a cooling drag reduction.

[FasGlas]

One thing to add to this hot oil discussion is, the oil coming out of the cooler is mixed with the very hot oil being pumped back to the filter adaptor, where most engine have the temp probe. I have three sensors that monitor temps at: The mixed oil (on the filter adaptor), in the sump at the screen just as the oil goes up the to the pump and on the output of the oil cooler (SW10599). On a warm SoCal day I'll show about 203F at the adaptor, 230F at the sump and 165F at the cooler output. This shows that the cooler is removing 65F from the sump oil, but when mixed at the adaptor the temp gains 40F for the 203F most monitors indicate. Adding additional oil coolers would lower the cooler output temp but the results may not be as drastic is you might expect. Less volume of oil would flow through the cooler(s) (path of more resistance) then flowing from the pump into the engine (least resistance). This is why adding a few more rows on a cooler shows little to no difference in cooling. The temp differential verses flow paths is not a big help. And, as mentioned earlier in this thread, the second cooler in series is less efficient then the first cooler. With all the said maybe the best approach is to get the right sized cooler and make sure it's flowing the required air efficiently. Obviously the hotter your flying area the more cooling you need.

[Randy]

Fasglas,

Thanks for posting that data. It makes me very curious to learn more about just what is going on with my oil temperatures before putting a second, or possibly a different oil cooler in my plane.

Since I have eliminated the vernatherm and installed the Lycoming "oil plunger assy", according to the schematic that Dan sent, it does not appear that I have higher temp oil from the sump mixing with the cooler oil from the cooler, unless of course the oil pressure should overcome the spring tension of the plunger which I understand would be 100 PSI or so. Can anyone verify?

Writing that statement has me wondering if the increased pressure drop of my Meggit 8432R could still be causing the mixing you refer to.

I am curious what led you to measure your oil temperature in three locations as you have done. Were you experiencing oil temp problems. If so did you make some changes to resolve the problems.

Thanks again for posting your data.


Randall

[DanH]

Originally Posted by FasGlas

One thing to add to this hot oil discussion is, the oil coming out of the cooler is mixed with the very hot oil being pumped back to the filter adaptor, where most engine have the temp probe. I have three sensors that monitor temps at: The mixed oil (on the filter adaptor), in the sump at the screen just as the oil goes up the to the pump and on the output of the oil cooler (SW10599). On a warm SoCal day I'll show about 203F at the adaptor, 230F at the sump and 165F at the cooler output. This shows that the cooler is removing 65F from the sump oil, but when mixed at the adaptor the temp gains 40F for the 203F most monitors indicate.

That's a fascinating set of measurements. I'm serious. Which oil filter adapter do you have?

Here's an AC adapter:

[Webb]

Check your engine ground strap. Corrosion or a loose strap can change the resistance and cause the reading to be inaccurate.

[FasGlas]

I'm using a Lycoming filter adaptor with a Lycoming Vernatherm, like most everyone uses. I didn't set out to monitor all these oil temp points but since I have an MGL iEFIS setup I can install many extra sensors and write gauges for them. So I figured I'd monitor temps that some pilots are curious about. I'm my case I made and installed temp probes at: Oil sump, oil cooled out, cowl behind the baffles, left and right Pmags. Using LM35x temp sensors and my MGL RDACs it's a simple installation. As it turned out I was able to see the cooled oil mix back with the sump oil at the adaptor probe point. Just a bit more information to ponder. And before anyone asks, I recently sent in my cooler and Vernatherm to Pacific for overhaul and test. One other test I haven't gotten to yet is connecting my manometer to the in and out of the oil cooler to see the pressure differential. More information I probably don't need.

[DanH]

Originally Posted by FasGlas

I'm using a Lycoming filter adaptor with a Lycoming Vernatherm, like most everyone uses.

Ok, so that's the AC-style adapter pictured above, right?

Your numbers say the vernatherm arrangement isn't doing as we've been taught...but I think I can see how it might happen. Let me get an adapter in hand...

[DanH]

Originally Posted by Randy

Since I have eliminated the vernatherm and installed the Lycoming "oil plunger assy", according to the schematic that Dan sent, it does not appear that I have higher temp oil from the sump mixing with the cooler oil from the cooler, unless of course the oil pressure should overcome the spring tension of the plunger which I understand would be 100 PSI or so. Can anyone verify?

Sorry Randy, missed your question. You're correct...the plunger should fully block the center hole in the adapter pad, the direct route from the pump.

[6 Gun]

If your not running your vacuum pump and the housing for it is still there make sure the drive gear is in the housing or you will lose a lot of oil pressure there.
Bob