Oil Pressure/Temp Issue

[AZBearhawk272]

Well........ my neck goes out a little bit here.
Reference point as IO-470D in my Bearhawk.
There does not appear to be a vernatherm which controls the amount of oil thru the cooler as a function of oil temp in this installation.

On Continentals it is in the oil cooler base adapter plate which is removed in this installation.

Continentals lube system is a bit different than Lycs.
The lube oil pumps are larger volume lower pressure.
Continentals can be quite happy at 35 psi all day long.

The Continental pump has a pressure set point adjustment and a relief valve within the pump housing.

Your numbers indicate that most likely you are getting adequate air and oil flow through the cooler.

The vernatherm will create some flow restriction which will cause the oil gallery pressure to rise. Then it will modulate the bypass flow as a function of temperature.

So most likely your installation will require an orifice in the line supplying oil TO the cooler with free flow back to the sump pan. This should raise your overall pressure. Provided the set points at the pump are correct. It they are too low then the oil bypass will happen at the pump without ever taking the journey to
the cooler. And the orifice will have little to no effect on the oil pressure.....

The engine OH manual has good description of the circuit and schematics. From my understanding of the system The adapter block at the front of the case should have been machined to house the vernatherm and not just be a hose takeoff. Possibly the airboat guys
have a block with vernatherm........

Aircraft Specialty Services might just be able to point you in the direction of an adapter.......

Info worth the price of admission...

Kevin D
# 272

[BravoGolf]

I don’t have a lot of experience with Continental engines, but here is something from the Operating Manual for the R (and other model) 470s.

3. INSTRUMENT INDICATIONS
a. Oil Pressure: The oil pressure relief valve will maintain pressure within specified limits if the oil temperature is within the specified limits and if the engine is not excessively worn or dirty. Fluctuating or low pressure may be due to dirty oil passing the valve.
b. oil Temperature: The oil cooler and thermostatic control valve will maintain oil temperature within the specified range unless the cooler oil passages or air channels are obstructed or the thermo valve held open by solid particles in the engine oil. oil temperature above the prescribed limit may cause a drop in oil pressure and will reduce the lubricating property of the oil permanently, leading to rapid wear in moving parts.
c. Cylinder Head Temperature: Any temperature in excess of the specified limit may cause cylinder or piston damage. Cooling of cylinders depends on aircraft baffles being maintained properly fit to the cylinder heads and barrels and other joints in the pressure compartment being tight so as to force air between the cylinder fins. Proper cooling also depends on operation practices. The recommended power setting (RPM and manifold pressure) should not be exceeded for long periods. Fuel and air mixture ratio also affects cylinder temperature. Excessively lean mixture causes overheating, even when the cooling system is in good condition.

perhaps a first step would be to change the oil and make sure it’s serviced with the appropriate viscosity oil. Unless you have already serviced it after purchasing the airplane. Fly it a couple of hours and see if that makes any difference. You haven’t mentioned if your CHTs are also running high during climb. As you level out and accelerate the improved air velocity lowers the oil temp and probably your CHTs. Your oil pressure at cruise is at the lower end of acceptable pressure.

Here is the Operating Manual I referenced, it may not be your exact model but it does cover the 470-R.

https://www.csobeech.com/files/TCM-IO470-Operation-Manual.pdf

i hope this is helpful

[BravoGolf]

I forgot to mention your oil temperature during climb is at the high end of the limit. This might have as much to do with baffling as anything else. Perhaps to aid in the diagnosis you could post some climb performance numbers. Is this only during a sustained climb to altitude or does it heat up on any climb? What is the climb attitude, pretty nose high? While the baffling won’t necessarily fix everything, fixing any leaks and the oil/filter service is a relatively inexpensive start to troubleshoot your pressure/ temperature issues.

[huntaero]

Hi Pitch what size of hose do you have to the oil cooler maybe they are too small not allowing enough oil to pass thru the cooler, on my IO-540 out of an Aztec has 1/2 in hoses. There is also a couple 90 degree fittings in your system which causes more restriction than a 45 degree fitting.

[huntaero]

The continental oil coolers come in different lengths ref McFarlane Aviation Products FAA-PMA Replacement Aircraft Parts so maybe a shorter oil cooler may correct the issue.