Hello
Just a few questions i want to ask.
What does it mean when a Cessna 172 Oil Temperature is reading high and the Oil Pressure is reading low? And how do we remedy it.
Same question but Oil Temperature Reading Low and Oil Pressure is reading High.
Another question would be what is the difference between a Center Zero Ammeter and a Left Zero Ammeter and what happens if it's Below or Above the line.
Will be doing my PPL Practical Test this Tuesday.

Much Appreciated

There are three logical reasons why oil temperature could be high.

1. The engine is overheating because of some unrelated problem and that extra heat is being transferred to the oil. A common cause would be a long period of high power operation at low speed such as a climb to very high altitude at low IAS. Also, a malfunction such as detonation or pre-ignition could be the cause.

2. An engine malfunction is not occuring, but the rate at which heat is being carried away from the oil is being reduced because of a problem with the oil cooler. Depending on where the oil cooler is situated, an obstruction in the duct that carries cooling air to the cooler could be the culprit.

3. There is nothing wrong with the engine or the oil cooler, but there is too little oil in the sump. If oil quantity is below the minimum on the dip stick, that smaller quantity of oil must carry the same amount of heat away. It becomes too hot [if you half-fill an electric jug, it boils much more quickly]. Hot oil has lower viscosity so oil pressure is likely to drop.

To understand the difference between the centre zero ammeter and the left-hand zero ammeter it is necessary to consider where they are situated in the system.

A centre zero ammeter is connected to the battery circuit between the battery and the bus bar. It should normally show a slight charge and is not affected when various items are turned on or off. It shows only the amount of current [amps] flowing to or from the battery.

A left hand zero ammeter is connected to the alternator circuit and it shows the total output of the alternator i.e. the total demand of the system. It does respond when various electrical loads are turned on or off.

It is unusual for one aircraft to have both types of ammeters except for some types with a dual scale that allows the pilot to select either the battery circuit 'BAT' or the alternator circuit 'ALT.'

Thank You Bob!!
This will help me !