Oil Pan

Stephen Fogel
December 10, 2019

Mounted to the bottom of the crankcase, the oil pan is a reservoir where engine oil is stored and drawn from.

Your oil pan is located at the bottom of the engine. Its primary function is to hold your engine’s oil supply. When your car is not running, all of your oil drains out of the engine and finds its way, with the aid of gravity, back into your oil pan, which is usually at the lowest point of the engine. The oil pan is sealed to the bottom of the engine with a gasket placed in-between.

Once you start your engine, the oil pump continuously sucks the oil from the bottom of the oil pan, and then distributes it to all the parts of the engine that need lubrication and cooling. This includes the valves and the camshafts, the pistons as they go up and down inside the cylinders, and the crankshaft, which sits right above the oil pan. This nonstop flow of oil, from the oil pan throughout the engine and back to the oil pan, continues until you shut off the engine.

Your oil pan is also where the oil drain plug is located. This is a bolt that is removed when it is time to change your oil at the recommended intervals. The plug is unscrewed to allow the oil to drain out of your engine. Once the oil has been drained, the plug is tightened, the oil filter is removed and replaced with a fresh one, and new oil is poured into the engine.

What are the signs of a bad oil pan?

A bad oil pan is important to watch for, because of how important your engine’s oil supply is. Losing your oil because can result in the destruction of your engine, and that will mean a very expensive repair bill. There are several symptoms of a bad oil pan. Let’s check them out:

  • You notice oil leaks on the ground under your vehicle: Leakage of oil onto the ground is a common symptom of a bad oil pan. Using a flashlight, try to see where the leaks are coming from. If it appears to be leaking from the area around your oil pan, and you also see oil on the oil pan itself, this could indicate a bad pan. Another possibility is that the drain plug might be loose or damaged. Before you start your car, check the oil first, to be sure that there is an adequate supply of it in the engine.

  • You see physical damage on your oil pan: Your oil pan is often the lowest point on the underside of your car. If your car bottoms out on a deep dip, or hits a very large pothole, the oil pan can get damaged. Depending on its construction, your oil pan could get dented or even cracked, which can cause some or all of the oil to leak out. If this should happen to you, do not drive your car; have it towed to the repair shop instead.

  • You oil level is low: If you have been practicing good car care, then you know that you should check your oil regularly. If you have been doing this, and you notice a sudden or steady loss of oil when you check it, you could have a bad oil pan, which is allowing an oil leak. Some oil leaks are very slow, or only drip when the car is running, leaving no traces when you park. If you don't check your oil regularly, or your car does not have an oil dipstick, then you may be alerted to a low oil condition by a dashboard warning light. Top up the oil and keep track of whether the light comes on again. If it comes on soon afterwards, get your car into the repair shop, so that the source of the leak can be found and fixed.

  • You see smoke coming from the engine: A bad oil pan can allow oil that leaks out to be deposited onto the hot exhaust system. The high exhaust temperatures then cause the oil to burn, creating smoke. If you notice smoke coming from under your hood, pull over as soon as you can, shut off your vehicle, and get everyone out of it. For your own safety, make sure that the smoke is not coming from anywhere else but your exhaust. Call your mechanic, and have this issue repaired as soon as you possibly can.

  • Your engine overheats: This is the worst-case scenario. If you lose enough oil because of a bad oil pan, the moving parts inside your engine will receive insufficient lubrication and cooling. Friction increases, and internal engine temperatures will rise, which can lead to catastrophic engine failure, if you don’t catch it soon enough. Pull over immediately and shut off the engine, to let things cool down. Do not open the hood to check anything before the entire car cools down, as you could burn yourself badly. Call your mechanic for advice on what to do next.

Should you drive your car with a bad oil pan?

It’s not a good idea. This is because a small leak can quickly turn into a big one, risking serious engine damage. The best course of action is to have your bad oil pan checked out by a mechanic, who will let you know the exact severity of the problem, and the best way to deal with it.

How do you fix a bad oil pan?

Your mechanic will first do a visual inspection of your bad oil pan to diagnose the source of the problem. It could be;

  • A loose drain plug
  • A leaking gasket
  • A cross-threaded or overtightened drain plug
  • The oil pan itself has been damaged from a road impact

Depending on the cause, the appropriate repair can be made. A loose drain plug can simply be tightened. A leaking gasket can be replaced, once that the oil pan is removed. A cross-threaded or overtightened drain plug (usually caused by a mistake during a previous oil change that causes leaking around the threads) can be fixed by re-tapping the drain plug opening to make new threads, and using a new drain plug that fits.

If the oil pan can be repaired, it can be removed, fixed, and reinstalled. If it has been damaged beyond repair, it will need to be removed and replaced with a new one.

For everything but the loose drain plug, the repair process goes like this:

  1. Drain the oil from the engine.
  2. Remove the oil pan from the bottom of the engine.
  3. Repair and/or replace the defective parts.
  4. Reinstall the oil pan, using a new gasket.
  5. Fill the engine with fresh oil and check for leaks.

Can you replace a bad oil pan yourself?

If you have good automotive mechanical skills, have dealt with this type of repair before, and have access to a lift, you may be able to replace an oil pan by yourself. Be aware that on some cars, the oil pan sits on top of the car’s chassis, rests on a subframe, or is blocked by the exhaust system. This could require lifting the engine up to get access to the bad oil pan, removal of the subframe, or unbolting the exhaust system. Now it’s a complicated job. This is not a low-effort DIY project, so it’s usually much better to leave this one to the professionals.

Stephen Fogel

About the Author

Stephen has been an automotive enthusiast since childhood, owning some of his vehicles for as long as 40 years, and has raced open-wheel formula cars. He follows and writes about the global automotive industry, with an eye on the latest vehicle technologies.

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