What Causes an Oil Pan to Leak?
There are some common causes for a leak from the oil pan: one would be a worn-out gasket and another might be impact damage. A third reason the oil pan can leak would be that the oil drain plug and/or its threads are compromised.
The pan itself may leak if it sustains impact damage from an accident or road debris. This is far more likely if the oil pan is cast aluminum than if the oil pan is stamped steel. In such a scenario, the damage will usually create a hole or crack in the oil pan.
Worn or Damaged Oil Pan Gasket
In many cases, the oil pan gasket will simply wear out over time and begin to leak around the edges of the oil pan. Be careful about condemning an oil pan, because oil can come from other places, gather around the gasket, and make it appear that the oil pan is leaking. The oil pan bolts on pans with cork gaskets can sometimes be torqued (gently) to mitigate an oil pan leak.
The oil pan gasket is sandwiched between the engine block and the oil pan. The gasket acts as a seal, preventing oil from leaking from between the two components. Some oil pan gaskets are silicone and come as RTV in a tube or a caulk cartridge, even if you buy the OEM gasket from the dealer.
Oil Pan Gasket Leak Symptoms
The symptoms associated with a leaking oil pan are fairly straightforward.
Puddle of Oil Underneath the Car
Engine oil dripping or pooling beneath your car can indicate a leaking oil pan or pan gasket. Of course, there are many other places your engine can leak from, so you’ll need to do some troubleshooting to determine the source of the leak.
Greasy Oil Pan and Exhaust System Where Oil has Blown Back While Driving
Buy a couple of cans of brake parts cleaner and some white foot powder spray. Put on some safety goggles or a full face shield. Keep your mouth shut while cleaning, along with some nitrile gloves, with the engine switched off (not running), wash the entire oily area as good as you possibly can with the brake parts cleaner and allow it to dry (this won’t take long).
Next, spray white foot powder or equivalent all over the suspected leak area as if you were spray painting it. Get ready with a bright light, and start the engine (stay clear of moving and hot parts!).
Usually you’ll spot the leak right away. CAUTION: Don’t ever get underneath any car unless you have it safely and properly supported! Some pickup trucks sit high enough that they don’t have to be raised for this.
Low Oil Level
A low oil level can also indicate a leak—potentially from the oil pan. Engines can leak oil from many locations, plus they can also burn oil. As such, you’ll need to do some homework before condemning the oil pan and/or gasket.
Smoke/Burning Smell Coming Out of the Engine Compartment
Smoke coming from under the hood is always a bad thing. An engine oil leak is one of several reasons why you may see smoke.
There are cases where the oil drips onto the hot exhaust, causing the oil to vaporize almost instantly. This isn’t something that happens due to an oil pan leak, however, unless the leak is bad enough that the oil blows back on the exhaust while driving.
Why Do Oil Pan Leaks and Leaks in General Happen?
Everybody knows combustion engines use oil, and unless you’re driving a race car with a “dry sump” system, you’ll have an oil pan, and every oil pan has a gasket of some kind.
In the oil pan, there’s a deeper area where the oil pump pickup tube (complete with a screen to prevent solid material out of the pump) will be submerged in whatever oil is available there. There’s also a baffle just above the deep area of the pan to mitigate oil sloshing so the pickup tube will always have oil available to send to the pump.
Oil can leave the engine by way of the piston rings and/or the valve stem seals so that it exits the engine through the exhaust system and out the tailpipe. It can out of the engine past hard oil seals, out of a failed oil pressure sending unit or from a breached oil cooler or a loose oil filter, and finally, it can get out of the engine because of bad gaskets. One way or another, if the oil supply within the engine is sufficiently depleted, well, we all know what that means. It’s bad news.
Seals, oil sending units, the oil filter, and the oil cooler have pressurized oil feeding them. Overhead cam engines have a pressurized oil feed through the head gasket to the cam bearings, and so the head gasket on those engines can develop a pressurized oil leak.
Oil pans and valve covers have gaskets to contain splash oil. Like the pressurized leaks, the oil pan makes a mess around the leak point, sometimes so that it drips out from under the car. This makes a mess of your driveway and tends to kill grass if a car is parked there.
How to Fix an Oil Pan Leak
In most cases, to fix a leak from the oil pan area, you need to either replace the gasket or the oil pan itself.
But there are some instances where you could get lucky by employing an easier fix.
Oil Pan Leak Quick Fix
NOTE: This may be a tough job. If you feel like you’re not experienced enough to pull this off yourself, take your vehicle to a professional.
Each time your car gets an oil change, the oil drain plug is removed and reinstalled. Because the plug is removed and reinstalled so often, the threads can stretch and the gasket can become worn so that it becomes the source of a leak.
Sometimes, to fix the leak, you may need to replace the drain plug with a new one and/or install a new gasket.
Important note: If the oil drain plug is difficult to remove after initially breaking it loose, get the right plug and replace it. Most oil drain plugs come with gaskets, but if all you need is an oil plug gasket, you can buy an inexpensive blister pack of assorted drain plug gaskets. Some people replace the drain plug every other time the oil is changed – it’s cheap – but you need to buy exactly the right drain plug – one size does NOT fit all.
Oil Pan Gasket Leak Repair
Typically, to fix a leak from the oil pan area, you’ll need to replace the oil pan or gasket. Usually the oil pan won’t need replacing unless it’s damaged externally or has oil drain plug threads that have been destroyed – this happens on aluminum oil pans over time more than on the stamped steel oil pans.
It’s important to note that, on many vehicles, other components must be removed first to gain access to the oil pan. In some instances, the entire engine must be removed from the vehicle to get to the pan. Front Wheel Drive vehicles may simply require the removal of exhaust or frame parts; rear wheel drive vehicles may require engine hoisting or removal. It’s best not to even try those at home. Make sure to consult the repair manual for your vehicle before digging in.
The following is a general outline for oil pan replacement on a vehicle that offers direct access to the pan.
1. Prepare the vehicle
Make sure the vehicle is parked on a level surface, set the parking brake, and chock the rear wheels. Then, safely raise and support the car using a jack and jack stands. Do NOT support the vehicle with a hydraulic jack while working under it!
Disconnect the negative battery cable.
2. Drain the oil
Place a suitable container under the oil pan. Remove the drain plug to drain the oil. Remove the container and reinstall the drain plug to prevent dripping.
3. Remove Necessary Components and then Unbolt the oil pan
After removing exhaust, frame parts, and anything else the shop manual procedures tell you to remove, locate all of the bolts holding the oil pan to the bottom of the engine block. Then, start removing the bolts one at a time.
4. Remove the oil pan
Finally, you can remove the oil pan. If it’s stubborn, tap on it gently with a dead blow hammer or rubber mallet to get it free.
5. Remove the old gasket
Remove the old gasket and carefully scrape any remaining material from the engine. Clean the mounting location on the engine with solvent—the area must be completely clean for the new gasket to form a good seal. Some engine oil pan gaskets are silicone and come in a caulking tube, which requires a good caulking gun. Silicone oil pan gaskets don’t generally leak to begin with but if you need to remove a pan with a silicone gasket, get ready for a fight – it can be very tough and you need to be careful not to damage the pan in the process.
6. Install the new gasket and the oil pan
After everything is clean, you can install the new gasket and the oil pan. Start by placing the gasket on top of the pan. Then, insert a couple of bolts through the pan to hold the gasket in place.
NOTE: Some replacement gaskets have four neat little plastic inserts than can be threaded into the pan bolt holes at each corner of the block so you can line the gasket up, snap the pan up onto the plastic inserts, and take your time doing the rest of the job; the pan will be slightly below it’s bolted up position, which enables you to line the gasket holes up and start all the bolts.
Finally, thread those bolts into the engine by hand.
Once the pan is in place, you can thread the rest of the bolts in (also by hand). Next, use a torque wrench to tighten the bolts to the manufacturer’s specification.
If you’re reusing the old oil pan, reinstall the drain plug and tighten it to specification.
7. Refill the engine with oil
Carefully remove the jack stands and lower the vehicle. Once you’ve done that, refill the engine with the correct amount of fresh oil.
Reconnect the negative battery cable, then start your engine and carefully check for leaks.
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