Mark99GT

Ok, can someone explain to me what exactly the oil pressure is a measure of? I know it is the internal pressure in the engine. But where is it measured? What are the causes of low oil pressure? Can oil pressure be affected by top end components? I hear referenecs to main bearing failures and subsequently low oil pressure, how does that work? These may be stupid questions, but I dont know the answers...thanks...

Colorado_Mustang

Oil pressure is how much resistance the oil is facing when being forced through the engine. Generally, it's measured at the output of the oil pump, but can be anywhere in the engine. The specifications for the engine's pressure will take into account where the pressure is being measured from.

Large clearances in the bearings, light weight oil (broken down oil, or just lighter weight than the clearances need), bad oil pump, or a plugged oil filter can all cause problems with oil pressure. Since the crank bearings are usually the first bearings to receive oil, they will have a big affect on the pressure your pump needs to put out.

Mark99GT

ok, thanks for the reply. Can you tell me about oil pressure and the top end? What will low oil pressure do to the top end? Can components in the top end cause low oil pressure? thanks

Colorado_Mustang

Low oil pressure won't allow a sufficient amount of oil to get to the top end, which accelerates wear. Top end components can affect oil pressure, but their contribution is very small in comparison to the bottom end.

Of course, there is an exception. There are engines that measure the oil pressure after the crank, in which case the top end directly controls the oil pressure.