How To Replace Jeep 4.0 Rear Main Seal – Here Is A Effective Way

Jeep 4.0 Rear Main Seal

Damaged fuel tanks and faulty rear main seals cause most oil leaks. The rear main seal must be broken if the fuel tank is not the issue. The best way to deal with this issue is to replace it.

How to replace the Jeep 4.0 rear main seal? We’ve broken down the entire process into 8 steps. Initially, you have to disconnect the power, lift the car and drain the oil. In the next few steps, you have to remove the necessary parts and replace the seal.

The process will be easier if you have all the necessary tools in your hands. Follow this article to learn all the steps we have mentioned here.

How To Replace Jeep 4.0 Rear Main Seal?

This is a challenging process, so we’ve broken it down into eight steps to make it easier to understand. Let’s check them out.

Jeep 4.0 Rear Main Seal

Step 1: Disconnect the Power

To begin, we must turn off the power, so disconnect the battery first. The negative line should then be disconnected. It will be safer to work now.

Step 2: Lift the Car

Lift the car a little with a hydraulic jack so you have room underneath to remove the rear main seal. If a hydraulic jack is unavailable, you can use an all-terrain jack or a bottle jack. You can still work without lifting the car, but it will be more difficult.

Step 3: Draining The Oil

Now, reach for the oil tank. This is close to the rear bumper and situated behind the axle with the fuel tank partially exposed below the bumper.

Using the appropriate wrench,

  1. Turn the drain plug counterclockwise until it is loose enough to be unscrewed.
  2. Hold on to it. Otherwise, the oil will begin to pour out as you pull the drain plug away from the oil pan.
  3. Give the engine five-six minutes to drain after the oil flow has slowed to a trickle.

Step 4: Remove The Starter

Power is transmitted through the starter, which is situated between the battery and the starter motor. You must first remove the starter solenoid. And after that, remove the 13-millimeter nut which holds the battery cable to the starter. This will disconnect the power.

By removing two 9-16 bolts, the starter can now be completely removed from the bell house. Please wait until all the oil has been removed before reinstalling the drain plug.

Step 5: Removing the Oil Pan Gasket

The oil pan gasket must be removed or you will be unable to reach inside. The gasket is held in place by several studs. Some studs are larger than others,

  1. so keep track of which ones go where.
  2. Now drop down the oil pan when all the bolts are removed. Removing the oil pan is tricky because there are lots of parts nearby. 
  3. Next, once the oil pan has been out, you should be scraping the mating surface because that place is greasy.

Step 6: Removing Main Girdle

You must remove the main girdle to access the rear seal if you have an older Cherokee. This girdle is also attached to several 18-millimeter bolts, so you must remove them all.

  1. One more thing to take out is the rear main cap. The rear main is held in place by two larger bolts.
  2. After removing them, you need to hit the cap with a hammer. They will become loose, making it simple for you to remove them without tripping.

Step 7: Installing Rear Main Seal

Here is what you need to do,

  1. In order to remove the rear main seal, you need to remove the upper part of the rear main seal. It’s a bit tricky to remove, so you need to use an awl and tap it with a hammer until you reach the seal. Once you reach the seal, you have to pull it with a needle nose plier until it comes out.
  2. The old gasket should be replaced at this point with a new one because the old gasket has some damage. Additionally, the rear main seal needs to be changed. If you don’t yet have a preference, you should purchase the seal from the Fel-pro brand. They provide a great quality product.
  3. It will be challenging to put everything back together. You must insert the lower half of the rear into the rear main cap. Then, you must install the new seal in the same manner as you removed the old one.
  4. Install the lower half of the rear main seal into the main cap with the lip facing the oil or the rear main bearing. After installation, you can use any heavy-duty oil stabilizer if you want.
  5. Now it’s time to feed the upper half of the rear main seal into the engine block. Use a little piece of paper to feed the lip over the crank journal. This paper will help you adjust the lip easily.

Step 8: Start Reinstalling the Part You Removed Earlier

At this point start reinstalling,

  1. Replace the rear main cap and cover it up. Following that, you can put the main girdle back in place. Don’t forget to turn them 35 feet per pound in a clockwise direction.
  2. Now you can use the blue inserts that came with the new gasket.
  3. When it’s finished, you can reinstall the oil pan gasket.
  4. And right after that, you can install the starter. That’s pretty much it. But you can also oil the necessary parts and change the oil filter if you want.

What Are the Signs of Rear Main Seal Failure?

Rear Main Seal

There are many signs that your rear main seal is failing, but these four are the most common ones among them.

  1. A leak of oil is present where the engine and transmission are connected.
  2. Illumination of oil light.
  3. Constant oil loss causes frequent low oil lights.
  4. Oil saturation of the vehicle’s underbody.

The primary responsibility of the rear main seal is to keep oil sealed inside the engine’s rear. As a result, when this seal is damaged, the primary issue that arises is oil leakage. Besides that, you also experience low oil levels and stains left behind from your vehicle.

What Are the Causes of Rear Main Seal Leak?

Rear Main Seal Leak

Many factors contribute to these problems, but not all of them are the owners’ fault; some of them are also natural.

  • Main bearing damage or misplaced due to overrun
  • Lack of optimum oil level
  • Faulty PCV valve (PCV valve can damage in different ways, you have to know the symptoms of a bad PCV valve)
  • Crankshaft dysfunction


Here are a few queries and responses related to the replacement of the Jeep 4.0 rear main seal. Hope this has given you some additional ideas on this subject.

How much does it cost to replace the rear main seal?

The rear main seal is typically priced between $300 and $900, which is quite high. However, the installation cost is a source of concern; depending on location, the installation cost will range between $500 and $800.

Is it possible to replace the Rear Main Seal at home?

Yes, you can do it yourself by following this DIY solution. But the truth is, this transition is not very simple. You must have some prior understanding of the car and its main aspects. In addition, you have all the equipment needed to run this operation.

Can I drive with a faulty rear main seal?

Yes, you can drive your car, but it’s very risky. When the rear main seal has a problem, oil leaks are common. Oil will leak from the undercarriage and oil tank. So it will be extremely dangerous. If an oil leak occurs, it is best to call for professional assistance instead of continuing to drive.

Final Words

We must be honest and admit that this is not the simplest task. But with the right knowledge and equipment, you can replace the Jeep 4.0 rear main seal and save a lot of money.

There are 8 steps in total, and we have done our best to give you thorough instructions on what to do and how to do it. In addition to the guide, we also discussed the primary causes and signs of rear main seal failure. Try it out if you believe you can do so and have all the required equipment.

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