It is incredibly important to have oil running through the moving components of an engine to keep it running smoothly and to prevent it from overheating and causing other issues. Low oil pressure is not good, because it can prevent oil from getting to the appropriate passages and parts of an engine that need lubrication. But, unusually high oil pressure can be equally as bad since it can signal other potential problems that should be addressed when symptoms exhibit themselves.
The most common cause of high oil pressure is a clogged oiling system, although there are several more. Some signs and symptoms of high oil pressure include the oil gauge indicating such, oil leaks, and high crankcase pressure. Unfortunately, unlike many other vehicle issues, including low oil pressure, there are relatively few signs and symptoms of high oil pressure.
What Causes High Oil Pressure?
There are many more causes of high oil pressure than there are signs and symptoms. Fortunately, many of them are easily fixable if the issue is found and rectified quickly. Like excessively low oil pressure, consistent high oil pressure can spell disaster for your engine if left unrepaired.
Clogged Oiling System
Any part of a vehicle’s oiling system – all the pipes, passages, and channels – have the potential to become clogged. This mainly happens over time as age takes its toll on any components and buildup becomes inevitable. However, it could also be caused by debris from various other areas and issues that occur over the life of the engine.
Many modern oils have chemicals built within their formulas to try and prevent this, but dirt, grime, and even other things like shards of metal or tiny pieces of rust have the potential to assist in clogging a vital passage. You can think of it as restricting water flow through a hose with your finger or blowing through a straw.
Learn More: What Happens If You Don't Change Your Oil
Dirty Oil Filter
An excessively dirty oil filter, or one that is damaged and not working correctly, is one of the potential enablers of a clogged oiling system. The filter is designed to remove particles from the oil that eventually reaches vital engine parts, but a damaged or excessively dirty filter will not be as effective or will not function at all.
Learn More: Types of Oil Filters
Incorrect or Bad Oil
Oil has different viscosities – the thickness or “thinness” of a fluid – depending on the type. Using the wrong type of oil or using bad oil has the potential to increase pressure within the oiling system. This is especially true if you use an oil that remains too thick for your particular vehicle as the engine heats up, but bad oil can cause high oil pressure regardless of the type.
Faulty Oil Pressure Sensor
The oil pressure sensor communicates the pressure to your vehicle’s sensor. If it detects unusual pressure, it will show false readings on your gauges. If the sensor is broken, it may show information that is not true. For this reason, a faulty sensor may not actually cause high oil pressure, but it may indicate that your vehicle has high oil pressure when it does not.
Faulty Relief Valve
An oil pressure relief valve regulates the oil pressure within the oiling system by expanding and contracting to allow excess oil to run back into the sump when necessary. Like most other things, it can get clogged or fail. When it does, it cannot allow excess oil to be rerouted through the pump and high oil pressure occurs.
Faulty Oil Pump
Most of the time, a faulty, worn out, or damaged oil pump will create a low oil pressure condition, but high oil pressure could be caused by an old pump with worn bearings. Of course, an oil pump that completely fails may cause no oiling at all. Most modern oil pumps are part of the timing assembly, run by the crankshaft rotation. This often means that complete failure of the oil pump is often a result of an additional engine failure.
Inappropriate Engine Temperature
Oil heats up as the engine heats up. As mentioned before, oil viscosity varies with temperature and is designed to work in different temperatures. If your engine is failing to heat properly, the oil will also fail to reach its maximum efficient viscosity and could be thicker than it should be. This causes the oiling system to work harder to push oil to the appropriate channels, and it increases the system pressure.
Common Signs and Symptoms of High Oil Pressure
Unfortunately, high oil pressure, though not as common of an issue as some other problems, is harder to diagnose than many other issues due to the lack of clear symptoms.
There are three main symptoms of high oil pressure, but a professional may likely have to assist with testing the oiling system if you suspect high oil pressure is present.
Oil Pressure Gauge or Light
Most vehicles are equipped with some kind of gauge or warning light when oil pressure becomes too low or too high. Gauges are much easier to read and keep track of since they show the exact pressure at any given time. Oil pressure lights simply illuminate when an irregular pressure is detected. Either way, a gauge or light is the first sign of a high oil pressure problem.
Everything in your vehicle is designed to function within certain parameters, and when your oiling system experiences pressures beyond the upper levels of those parameters, they begin to fail. This is common at attachment points, seals, and gaskets. Oil pressure that is too high over a long time will cause leaks throughout the system and potentially onto the hot engine, posing an additional problem.
High Crankcase Pressure
The crankcase is the part of your engine that houses the crankshaft and other vital moving parts. A professional mechanic will most likely have to assist with crankcase pressure testing, but it can be a good way to diagnose high oil pressure if it is suspected. Elevated crankcase pressure can be a sign of other engine issues, but this too has a sensor that can trip the check engine light if abnormal values are detected.
Potential High Oil Pressure Repair Costs
After diagnosing the reason for excessively high oil pressures within your vehicle, the cost of fixing the issue can vary quite a bit. Something like a replacement oil filter or even draining and flushing the oiling system after using incorrect or bad oil can be as little as $20 to $100 to repair depending on if you do it yourself or take your vehicle to a shop.
A replacement oil pressure sensor is also not that expensive since it is generally easier to access than the pump and relief valve. A new sensor can be as little as $120 with labor costs generally remaining under $100.
Larger issues like having to replace an oil pump or an oil pressure relief valve will be more expensive since this usually requires having to dig deeper within the engine to access these parts. Replacing these parts usually requires removing the front or bottom of the engine, sometimes requiring the removal of other large vehicle components to even access the engine.
In the worst-case scenario, oil pump replacements can be up to $2,000, mostly due to the labor costs involved in accessing hard-to-reach parts. An oil pump itself is usually much cheaper than the labor costs incurred. Finding and fixing a blocked oil passage can also be expensive if the location is unknown and several hours of work are involved with removing parts to find where the blockage exists.
Having excessively high oil pressure in your vehicle is not as common as having low oil pressure in your vehicle, but it does happen, and it can be just as bad. Clogged oil channels, a bad oil pump, the wrong kind of oil, a dirty oil filter, or a bad pressure relief valve can all cause high oil pressure. Unfortunately, your oil gauge, oil leaks, and increased crankcase pressure are the only real signs of high oil pressure. Additionally, depending on the issue, the repair cost can vary from $20 to well over $1,500.