On Jun 9, 9:06 am, Blanche wrote:
I was seeing oil temps in the red, oil pressure ok but I still landed
immediately. Turns out the wire on the oil temp unit on top of the
engine (don't know what that is) was loose. Correct wrench to remove
the nut, washer and wire. Clean everything. Replace. Tighten correctly
(yes, an A&P was there - next door hangar). No more problem with
oil temps.

The easiest & cheapest fix I've ever had.

Rising oil temps with electric gauges can sometimes be blamed on
a poor engine grounding strap or alternator ground cable. If there's
resistance between the engine or alternator and the airframe, the
electricity looks for other paths and can find a small one via the oil
temp sensor (which is screwed into the oil filter adapter and is
thereby grounded), through the sensor and up to the gauge, through the
gauge to the bus. The electron flow is in the same direction as the
gauge's normal flwo from the sensor and so any additional flow will
cause a higher gauge reading.
I would suspect a ground connection that is losing its
effectiveness as it heats up. Back of the alternator, ground strap at
the engine or even on the mount, alternator ground at the firewall.
Clean and tighten them. And then run a small wire from some small bolt
on the engine accessory cover near the temp sensor, through the
firewall and to the gauge backplate. That's a Cessna fix for the
issue.

Dan