Contents: Low oil level ⇓ Clogged oil filter ⇓ Liquid or diluted oil ⇓ Oil pump pressure relief valve stuck…⇓ Damaged oil pump oil pickup tube ⇓
Oil pressure can be low for several reasons that do not require engine repair. These include the following: low oil level; the oil filter is clogged; liquid or diluted oil: the oil pump pressure relief valve is stuck in the open position, the oil pump oil intake tube is damaged.
Low oil level
Checking the oil level is necessary before deciding to repair the engine. When the oil level is low, the oil pump pickup tube has difficulty drawing in enough oil to maintain proper pressure in the engine's lubrication system. Low oil pressure under these conditions is a small evil compared to the damage that low oil pressure can cause. Probably the best preventative measure in this case is to check the engine oil level at least once a week and add oil as needed.
Clogged oil filter
The simplest or most obvious reason for low oil pressure is a clogged oil filter. Unfortunately, there is no way to say for sure that this is usually the result of carelessness or mistakes. If the oil has not been changed during the time the engine suffered from low oil pressure, the oil and filter should be changed.
Liquid or diluted oil
The idea of buying oil that is too thin (i.e. with low viscosity), pretty stupid. If you are using oil that was purchased with a car engine oil chain, it is almost impossible to purchase oil that will itself cause low oil pressure. Some people may disagree with the statement that using thick, high viscosity oil will cause high oil pressure. This is often true. However, if the engine lubrication system, oil pump and bearings are in good condition, even low viscosity oil will be able to provide the required oil pressure.
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Diluted oil is another matter. Oil becomes diluted in several ways. Perhaps the most common method is the one described below. When the engine is running, especially after starting, some of the exhaust gases escape past the piston rings and enter the engine crankcase. These gases contain some amount of unburned fuel. Unburned fuel dilutes the engine oil. This dissolved oil can cause low oil pressure. But an even more critical phenomenon can occur, which is that unburned fuel, combined with moisture in the crankcase, can form an acid that can damage bearings and their surfaces long before the low oil pressure caused by its dilution can damage the engine.
Another way: Engine oil can become diluted by engine coolant (coolant). If the cylinder head gasket starts to leak, or if the cylinder head or block cracks, coolant can leak into the combustion chamber and/or crankcase and dilute the engine oil.
While low pressure due to diluted motor oil can be diagnosed by simply changing the oil, the question is: does the engine need major repairs due to a problem caused by diluted motor oil? Another question is: how much damage has been caused by diluted motor oil? A simple oil change may increase the pressure, but the engine may already be damaged and this damage must be repaired before it becomes catastrophic.
Oil pump pressure relief valve stuck open
All engines are equipped with an oil pressure reducing valve in the oil pump. The valve's job is to limit the oil pressure to a level that prevents the oil filter from turning into a shrapnel grenade. Occasionally the relief valve will stick open, allowing oil to be pumped by the oil pump and returned to the oil pan. This fault is very difficult to diagnose and may require a complete engine overhaul.
If time is not critical, remove the oil pan and install a new oil pump. While it is possible to repair the relief valve, there is little point in removing the oil pan and doing the repair "just in case."
Damaged oil pump oil pickup tube
When the oil pump is removed during the installation of a new pump, check the feed pipe for possible damage. If the tube is cracked or loose, the oil pump will not be able to suck oil from the oil pan. This will cause low oil pressure. Before replacing the oil pump, make sure the feed pipe is in good condition.