In the early days, oil was delivered to an engine’s components much differently than it is today. The first engines were lubricated with drip feed systems, which dropped oil into all its moving components, and on ships, there were workers known as “oilers” who filled up pots of oil above the moving parts.

Since the beginning of the 20th century, however, internal combustion engines began using a force-feed system, in which oil is pumped around, or forced, to the engine’s many parts. Engines today use a completely forced-feed lubrication system, and a critical component of this system is called an oil pump.

The oil pump is the heart of a lubrication system. The pump sucks up oil from the oil pan and forces it through the engine’s oilways — then, the oil drips back into the sump and gets recirculated. The oil pump is absolutely necessary for an engine to function and, if it malfunctions, it will lead to a costly engine failure.

In this handy guide, we’ll explain what happens during an oil pump failure. You’ll also learn to recognize the signs of a malfunction and understand their causes, so you can care for your boat’s engine.

Oil Pump Failure — What It Is and What You Need to Know

The purpose of the oil pump is to pressurize oil and circulate it to all moving parts of an engine. If an oil pump fails to do this, the moving parts of your boat’s engine cease to function properly — which is why oil pump failure is such a serious issue and why it’s so important to understand what can cause it.

Common Oil Pump Failure Symptoms

So, what happens when your oil pump goes out? Marine engines are complex machines — each part serves a purpose, and when one part stops working, other parts follow suit. When several parts begin to fail, your marine engine may show a wide variety of symptoms, making it difficult to pinpoint the root of the problem.

There are many warning signs when it comes to oil pump failure, the most common of which include:

The engine or oil light indicator begins to flash: This is the most common first symptom of an oil pump failure, although it doesn’t necessarily mean the oil pump has failed. The oil light typically means that oil pressure is low, which is a common symptom of an oil pump failure, but it can also mean there’s a leak or the engine is burning oil. You may be able to solve this problem by simply checking the dipstick and, if the oil is low, adding some more. If you do this and the light does not turn off, check for other signs.

The oil pressure is low: An inferior oil pump will be unable to pump oil properly through the system, resulting in low oil pressure that may cause significant damage to the engine.

The hydraulic lifters are noisy: Hydraulic lifters are critical for your engine to operate properly and must be properly lubricated. If the engine is running normally, the lifters are practically silent, but if the oil flow is cut off, they’ll start to make noise. Replacing these lifters is extremely costly, so lubricating them adequately is of the utmost importance.

The valve train is noisy: This component may also make noise if the oil pump starts to fail. Just like with the hydraulic lifters, keeping this part well lubricated will keep it operating quietly. The valve train includes the seals, pushrods and valve guides.

The temperature of the engine increases: The oil that is pushed through your engine helps to cool your engine by lubricating its moving parts. Without sufficient oil, the parts will begin to rub against one another, increasing the overall temperature of the engine. If this happens, the heat light should turn on to alert the operator of the issue. Overheating of the engine should be addressed as soon as possible, as this problem can lead to much more serious issues.

The oil pump itself is noisy: Although this problem is less common, it has been known to occur. If your oil pump is making noise, you will hear a loud whirring or whining sound, which is due to the wearing down of the internal gear mechanism.

Experiencing an oil pump failure is not very likely, but if you notice any of the above symptoms, there is a good chance your oil pump has failed. In this case, it is highly advisable that you have your engine checked immediately.

10 Causes of Oil Pump Failure

Since marine engines are so complex and inter-connected, there are a myriad of problems that could cause your oil pump to fail. Identifying these issues and fixing them is key to keeping your marine engine running smoothly.

Various issues can lead to oil pump failure, but the most common causes are:

1. Low Engine Oil Levels

If you don’t have enough oil in your engine, you may have a problem. There must be enough oil in the engine to properly circulate through the engine and enough to adequately coat all of the required surfaces. If the level isn’t high enough, the pump will be forced to deal with the additional friction resulting from insufficient lubrication. This will cause some mechanical problems, including warped pump components, which eventually will lead to complete failure of the pump.

If you decide to add oil yourself, make sure you are following all of the specifications recommended by the manufacturer. Refer to your engine manufacturer’s manual to find out what type of oil they recommend for your engine.

2. Infrequent Oil Changes

If you dread oil changes, we completely understand — to many people, they feel like a near-constant chore, and buying new oil and filters can be quite an expense. However, we cannot overstate the importance of staying on top of your oil changes, as they’re absolutely necessary for keeping your engine’s oil fresh. If you’ve ever performed an oil change yourself, you’ve likely noticed that the color of the oil coming out of your engine is nothing like that of the new, clear oil that you pour in.

When oil makes its way through your engine, it collects sludge, grime and debris from the wear and tear of the engine’s moving components. All of these things accumulate in the oil and keep it from lubricating the parts properly. Instead of protecting the parts against wear, these particles actually cause the parts to wear down even more — particularly the oil pump.

3. Wear and Tear Over Time

This issue applies to almost everything mechanical, and oil pumps are no exception. Regardless of how high-quality your oil pump is, it won’t last forever and will eventually give out due to unavoidable wear and tear. Even if it doesn’t fail completely, at some point, it will cease to perform optimally and will have to be replaced, so your engine can regain its proper function.

4. Engine Sludge

Engine sludge is a substance that forms on and around a motor when the oil starts to break down. When there’s engine sludge on your engine, this means the oil cannot lubricate your engine’s moving components properly.

Here are some tips to help you identify engine sludge:

1. Crank the engine: Check if the engine light is on. Also, look out for the oil change notification light. Either one of these could signify engine sludge.

2. Turn the engine off: Walk over to the engine and inspect it.

3. Check for warning signs: Look for signs of engine sludge or oil splatter on the engine’s exterior. Generally speaking, engine sludge has the appearance of dark, thick oil and forms in tiny clumps. If you notice any engine sludge on your engine’s exterior, chances are you’re dealing with engine sludge.

4. Check the oil pan: Take the oil cap off the oil pan and take a look inside. You might have to use a flashlight to see it. If everything is normal, the oil pan’s contents should look clean. While the parts and walls should be covered in oil, they still should look metallic silver underneath. If your oil pan has any hint of sludge, this means there is sludge in the engine.

5. Oil Contamination

Oil contamination refers to when anything besides oil makes its way into your oil. This often happens if the oil is not changed regularly, as oil that stays in your engine for too long will pick up too much debris. However, oil can also be contaminated in other ways — for example, other fluids can make their way into your oil, such as your fuel. Contaminated oil can seriously harm your oil pump.

6. Open Bypass Valves

If your engine oil bypass valves have been set to “open,” your oil pressure may be lower as a result. Open bypass valves are often caused by debris in your oil, which can consist of dirt or shavings from the camshaft, pistons, crankshaft or other internal hard parts of the engine that have been damaged. This problem can be solved by removing each of the oil bypass valves and cleaning out any debris. It’s also a good idea to clean the bypass valve bores. Once you’ve cleaned the bypass valves, you should then change the oil and the oil filter.

7. Malfunctioning Oil Passages or Oil Lines

An open oil passage or oil line, whether it’s disconnected or broken, will cause the pressure of your engine oil to decrease. The engine builder should inspect the oil passages for wear and debris. In some cases, oil galleries may not be lined up to allow the oil to flow normally. Inspect the oil lines and make sure they’re hooked up correctly and that there are no tears in the line.

A damaged or missing piston cooling nozzle could also be the cause. A piston cooling nozzle serves to cool a piston by directing oil to its bottom and also lubricate the piston pin. Installing this nozzle incorrectly, restricting its normal movement or breaking it can cause the piston itself to stop working.

8. Restricting the Oil Suction Tube

In the oil suction tube, there’s an inlet screen that can become damaged or clogged. This restriction will lead to cavitation and cause the engine oil pressure to go down. To solve this problem, inspect the oil pickup tube’s inlet screen and take out any materials that could be restricting the flow of oil.

Low pressure of the engine oil could also be caused by the oil pickup tube sitting improperly and sucking in air instead of oil. Take a good look at the oil pickup tube’s joints and see if there are any cracks, damaged O-Ring seals or alignment issues. We recommend you remove the oil pan to access the oil pickup tube.

9. Incorrect Bearing Clearance

If there is too much clearance for the engine bearing, this could cause the oil pressure to decrease. Examine the components of the internal engine where the bearings are and make sure they’re in good shape. If they’re worn, we recommend you replace them or have them repaired.

10. Improper Installation

If the oil pump fails immediately or soon after it’s been replaced, there’s a good chance it has been installed improperly. Installing an oil pump correctly can be a little tricky — from giving gear enough backlash to shimming the pump properly, it is easy to make mistakes that will lead to failure of the pump.