C206T high oil temp

[gasmonkey]

I am currently flying a T206H. The analogue oil temp is consistently high 245, at cruise with cowl flaps open. Even with low OAT. Other gauges are all in the low green. Oil pressure in green too. EBM have TIT, CHT oil temp all normal. I had the gauge and the sensor replaced. Anyone else had this problem? Advice please.

[captjns]

have your ensure that every item from the panel to the oil tank are Cessna Approved parts, per their Mx Manual? Have you been present when the mechanic performed a bench test of the gauge and probe too?

[gasmonkey]

I have. The analogue sensor is before the oil cooler and the digital one after. Pilots/LAME have suggested the the problem is with the location of the sensor and to ignore it and keep the oil temp below 180 on the digital gauge. That makes me a little nervous. Before I have the oil cooler removed and flushed I would like to know if anyone else has had similar problems

[Typhoon650]

I'd consider an oil analysis. It will be able to determine if the oil is indeed being operated past it's optimum temps.
On an air cooled engine (especially a turbocharged one which keeps turbocharger bearing temps under control with oil cooling) cooler oil is definitely better.
Another option may also be a cheapo electric temp sensor jerry rigged on the cooler for a flight.

[Machinbird]

How about oil cooler problems causing high temp problems?
Damaged fins, sludged up oil coolers, and stuck vernatherm valves can cause high oil temp.

Try this link for some pointers.
Oil Temperature Control Systems

[Octane]

Is there the correct quantity of oil in the sump? i.e. is the dipstick reading high, is it the correct dipstick?

[gasmonkey]

My suspicion is the vernatherm or a blocked oil cooler. Oil temp before cooler is 245+ and after 155!

[Typhoon650]

That would indicate the cooler is doing it's thing. So why is the engine heating the oil so badly is the question
.

[Machinbird]

That would indicate the cooler is doing it's thing. So why is the engine heating the oil so badly is the question

The large difference in temperature in vs temperature out could also be an indication of low flow across the cooler. Without knowing what is normal, it is difficult to troubleshoot from outside.
The engine's ability to heat the oil is finite unless you have a bearing beginning to fail.
If it was my aircraft, I think I'd be getting my hands dirty about now.

[roulishollandais]

Originally Posted by Machinbird

If it was my aircraft, I think I'd be getting my hands dirty about now

Your aircraft will be happy
When I dropped jumpers with the C206 I had to control every cylinder head temperature.

[gasmonkey]

Pulled the vernatherm . Wasn't seating correctly. Replaced. Oil temp pre cooler now 190 and post cooler 170. This after climb to 7500 at 80kts. Oil pressure also higher. Looks like problem solved. Thanks for all the replies.

[noughtsnones]

From another life; faulty Vernatherm devices were twice (eventually) rooted out as cause of strange fuel delivery behaviour, i.e. downstream of fuel/oil heat exchangers.
Pesky things, these valves that move (or stop moving) without telling the software!

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[Lumps]

If you haven't already, replace that oil. It would be not so good anymore. I've had two oil pumps slooowly let go on me and one thing that became evident was how good oil is until it's about 10 hours old, then it starts to deteriorate. I'd say the stuff that had been cooked in that motor is past its prime!

[roulishollandais]

Overlooking initial troubleshooting

Originally Posted by Machinbird

Try this link for some pointers. Oil Temperature Control Systems

Thank you for that excellent link. It showed me that we emphasized too much the cylinder head temperature, only useful for us to protect the cylinder from temperature shocks in dropping skydivers work, flying mostly max power to climb and zero power to descent.

That article from AVweb shows it is important "to do this stuff long before any problem become apparent" , to "take time", to "consider the system as a whole at each step", to be "methodical" with "attention of detail". Excessive oil temperature may be very dangerous in flight not only a problem of saving time and money.

Good lesson from Old and Wise-Timer way of working.

It is easy to have seemingly good stats of incidents and accidents with mostly new aircrafts as A is claiming every day but probably maintenance Teams have not a better formation than push-button pilots. Airlines will have to pay a little later more superficial methods (replace some electronic card, and other stuff as they are doing on modern cars..).
I remember the AP trim alarm light flashing when starting IAS descent with excessive speed of our MD83 : "if it stops it is not a problem" said the Chief Pilot . But flight after flight wires length increased dangerously. Happily we had no rupture, but one day , in pitch, the plane crossed the 3000 FT Armed Height and descent clearance descending still 1000 FT/min, and in roll another day it finished with a Dutch Roll, with Passengers on board, of couse. The Chief Pilot was sure the pilots did not need why that crazy light was flashing 5-10 seconds at TOD every flight...

[Machinbird]

Pulled the vernatherm . Wasn't seating correctly. Replaced. Oil temp pre cooler now 190 and post cooler 170. This after climb to 7500 at 80kts. Oil pressure also higher. Looks like problem solved. Thanks for all the replies.

That is what PPrune is for. Glad to see that you are pro-active in your maintenance approach.
I agree with Lumps on his recommendation.

[StanleyMedic]

After reading this I was worried about my Vernatherm. The oil temp generally touches redline while all other values are within normal range. Removed the oil temp probe....put in a pan of oil with two real thermometers and heated. The probe was reading +35F. Easy replacement.