The Mystery Of Pressurized Oil Pans: Solved!

The oil pan is not under pressure, but the oil itself is. The oil pan is simply a reservoir for oil, which the pump pulls from. The oil pressure measurement is taken from the head or the block itself. The oil pan can be under suction, and there is also crankcase pressure. The oil pan will only hold as much pressure as the dipstick will hold.

The oil pan is not under pressure

The oil pan is simply a reservoir for the oil, and the pressure comes from the pump. The pan is not pressurised, and if it were, the dipstick would pop out. The oil itself is under pressure, but not the pan. This is why oil pans are designed to control oil slosh, with deep sumps or baffling, to prevent the pickup from becoming uncovered and sucking air.

Oil pans can be under moderate heat and minimal pressure from the crankcase, but this is not the same as oil pressure. The oil pan is not a pressurised component, and the oil pressure measurement is taken elsewhere.

Oil pans can leak

Secondly, impact damage can cause a leak in the oil pan. This is more likely to occur in cast aluminium oil pans than stamped steel pans. The impact will usually create a hole or crack in the pan.

Other potential causes of an oil leak include a compromised oil drain plug and/or its threads, or a punctured oil filter.

Symptoms of a leaking oil pan include a puddle of oil under your vehicle, a greasy oil pan and exhaust system after driving, low oil levels, and a burning smell coming from the engine compartment.

It is possible to drive with a cracked oil pan, but it is not recommended as it can be detrimental to your engine's health. If you need to drive before replacing the pan, ensure you top up your oil frequently and do not exceed the 10-mile mark.

Oil pans can be resealed

To detect an oil leak, begin by cleaning the engine with a degreaser and follow the trail of external oil to its highest point. If the evidence leads to the top of the oil pan, the solution will be more labour-intensive.

A service manual can be a valuable resource when removing the oil pan. Other parts and brackets might need to be removed first to access the pan and its bolts. The manual will also describe vehicle-specific procedures, such as if the crankshaft needs to be rotated before the pan can be removed.

• Clean off old gaskets or sealing material and the oil pump pick-up screen.
• Install new gaskets, seals, or sealing liquid.
• Add engine oil and replace the oil filter.
• Torque the oil pan bolts to the manufacturer's specification.
• Refill the engine with the correct amount of fresh oil.
• Start the engine and check for leaks.

It's important to note that the procedure may vary depending on the vehicle, and in some cases, it may be necessary to remove the entire engine to access the oil pan.

Oil pans can be replaced

If you notice any of the following signs, it may be time to replace your oil pan:

• Illuminated warning lights on your dashboard, such as the oil pressure or check engine lights.
• Low oil levels.
• Oil leaks that leave trails or puddles under your vehicle.

Replacing an oil pan can be a DIY project, but if you are not confident in your automotive skills, it is best to leave this task to a professional. The cost of replacing an oil pan can vary depending on the year, make, and model of your vehicle, ranging from $20 to $1000.

• Jack up your vehicle and place jack stands at the appropriate points to support it safely.
• Drain the oil by removing the oil filter and drain plug, allowing the oil to drain into a pan.
• Remove the oil pan bolts, leaving one at each corner loosely in place. You may need to gently tap or pry the pan away from the engine block. Once the pan is loosened, remove the remaining bolts and carefully take out the oil pan without damaging the oil pickup located within.
• Clean the area on the lower engine block where the oil pan attaches, as well as the oil pan itself.
• Remove the old gasket material from the oil pan and engine block mounting surface. Clean and dry both surfaces.
• Apply a thin film of rtv to the oil pan mounting surface and let it set for a few minutes. Then, install the new pan gasket, following the directions on the rtv package.
• Insert the oil pan bolts by hand to start, then torque them to the manufacturer's specifications to avoid distorting the oil pan and causing future leaks.
• Reinstall the oil pan drain plug and new oil filter. Fill the engine with the recommended oil.
• Check for any obvious leaks before lowering the vehicle. Start the vehicle and let it run for a minute, then turn it off and check the oil level again. Top off if needed.

It is important to maintain proper engine oil levels and change your oil at normal intervals to ensure the health of your vehicle and its engine.

Oil pans can be baffled

A baffled oil pan will have compartments separated by a hump, with the oil pump located in the shallow compartment, and the oil pick-up in the deeper one. The compartment where the oil pick-up is located is designed to trap oil. It is cordoned off with trap doors that only open inward, allowing oil to enter but not exit.

The size of the trap doors is important. They should be as large as possible without interfering with each other or the pickup. The openings in the baffles should be slightly smaller than the doors so that they seal when the oil slings against them due to g-forces. It is also important to limit how far the doors can open so they don't flip up the wrong way or touch each other.

Another feature of baffled oil pans is a scraper. As the crank spins, beads of oil are flung around the inside of the engine. The scraper catches most of these, preventing the oil from going up into the cylinders and returning it to the pan.

Frequently asked questions