Hot oil Temp M 20J

[ltdoyle]

I have an IO-360-A3B6D that incurred a massive crankcase crack. It was disassembled and re assembled in a yellow tagged overhauled case and reinstalled into the airplane.  Ever since, the oil temperature gauge “pegs” out on every flight. It starts and runs fine.  The cylinders were sent off and “nuChromed” and have excellent compressions.

I removed the Rochester temperature sensor and put it in hot oil with a thermometer.  I have OEM analog gauges, but they appear to be reasonably accurate.

I removed the vernatherm and placed it in hot water.  It expanded accordingly and appears fine.  I endoscoped the vernatherm housing and the seat looks good, no noticeable nicks or anomalies.I removed the oil cooler and sent it off and had it overhauled, and checked the oil lines for any obstructions or kinks. I have also reversed the oil lines to see if that made a difference.

So far, nothing I have done has remedied the hot oil temperature.  I am open to suggestions.  Also, I know the vernatherm expands when hot, but how does that open the oil cooler lines?  Does the seat move, and if so, could something be preventing it from opening up?  

All help appreciated!

[Slick Nick]

It’s likely an issue with the gauge. 

[ltdoyle]

Possibly, but I heated oil in a pan to 200 F and the gauge was reporting pretty close to where 200F would be. Oil pressure drops from 90psi to about 65, so I think I am getting hot…

[PT20J]

2 hours ago, ltdoyle said:

Possibly, but I heated oil in a pan to 200 F and the gauge was reporting pretty close to where 200F would be. Oil pressure drops from 90psi to about 65, so I think I am getting hot…

Given those two data points, it sounds like a real issue. Are you sure that the oil cooler lines are connected properly? What does the overhauler say?