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Oil Temp

Manchu16

Active Member
Starting to get cooler here in the SE. My Carb'ed O-320 normally runs about 150-155 F during the summer with the oil cooler vent open. It was a 50F OAT today and with the cooler vent shuttered (Back side of the cooler), I could barely hold 150F. I have two temp probes (Vans and EI Engine Mon). They are within 5 F of each other, so pretty confident on the temps.

Thoughts on how I can warm up the oil without driving my engine temps through the roof?
 
Starting to get cooler here in the SE. My Carb'ed O-320 normally runs about 150-155 F during the summer with the oil cooler vent open. It was a 50F OAT today and with the cooler vent shuttered (Back side of the cooler), I could barely hold 150F. I have two temp probes (Vans and EI Engine Mon). They are within 5 F of each other, so pretty confident on the temps.

Thoughts on how I can warm up the oil without driving my engine temps through the roof?

I'd focus on the pressure issues first. I responded to that post. Shutter in front of cooler works better than behind. I only get 155-160 in the winter (no shutter). Engine hasn't rusted or blown up yet.
 
Now that the oil pressure issue is fixed, off to the oil temp issue. I know it is not the same issue as the oil pressure, bad gauge, since I have two discrete sources agreeing.

Yes I have a vernatherm, not the bypass valve. I didn’t do the boiling water test, but I did confirm when cold it is in the retracted position. So at a minimum I have oil going to both the cooler and the sump when cold. I guess if the vernatherm opens before the 180 mark, I could be cooling the oil early.

I taped the entire front of the cooler with metal tape and confirmed the back louvers were closed on the cooler. Oil jumped up to a peak of 163 with OAT of 67F at cruise.
 
Found it

From the top plenum, I have the oil cooler than the oil cooler shutter on the back side. For S&G I flew the airplane and measured the oil temp with the shutters closed, 146 or 79 degrees hotter that OAT.

I flew with the shutter open on the same flight after 10 mins to allow temps to stabilize. 144 or 81 degrees hotter than OAT.

I then landed and removed the shutter completely. 146 or 81 degrees hotter than oat (temp climbed by 2* between tests)

I placed the shutter infront of the oil cooler and flew it the next day. I had to modify the lip of the baffle to allow the shutters to sit flat.

Cooler shutter open 162 or 93 degrees hotter than oat (remember next day, but about the same time and we had stable weather all week.

Cooler shutter closed 188 or 119 degrees hotter than OAT.

So for me it seems like having the cooler shutter on the back side of the oil cooler is about as effective as not having one.

The cooler shutter on the front is good for about 20 degrees of oil temp. YMMV, but was surprised how useless the shutters were on the back of the cooler.
 
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