When you first buy an older Jeep you sometimes notice leaks, the most common is the Jeep oil filter adapter leak. This leak usually results in your starter getting covered in oil because it is directly under the oil filter—you can’t really miss it. In fact, it isn’t really the oil filter that is leaking, but rather the Jeep oil filter adapter, and more specifically, the oil filter adapter O-rings. The good news is they are fixable, and it is a relatively cheap and easy job.
To fix the Jeep oil filter adapter leak, you need to replace three O-rings inside the Jeep’s oil filter adapter. It takes just under an hour, if you know how to do it (there is a secret to doing this repair). I have personally changed the Jeep oil filter adapter O-rings three times on three different Jeeps. The project costs about $12 for the parts and about $18 for two tools (if don’t already have them). It also helps to have a set of ramps, wheel chocks, a 1” x 2’ steel pipe, some wrenches, brake cleaner or engine degreaser, red Loctite, rags or shop towels, eye protection, disposable gloves, and a catch basin or bucket.
The truth be told, I attempted it unsuccessfully two other times before I got it right. After I figured it out I did the other two Jeeps in about 45 minutes each. It is easy, once you know how to do it.
What is the Jeep Oil Filter Leak?
The Jeep oil filter leak is really the O-Rings inside the oil filter adapter. When they fail, the oil leaks out.
Why Does the Oil Leak?
The oil leaks because the O-rings, (usually the large one), are no longer acting as gaskets. What you will notice when you finally get the oil filter adapter out and open, is that the large O-ring is smashed flat and is extremely brittle.
The heat of the oil, the engine, pressure and time have caught up to the O-ring. It should be round and springy to the pinch. When it becomes flat and brittle the seal is compromised, and the leak begins.
How to Diagnose the Jeep Oil Filter Adapter Leak?
You can’t really miss the leak. The area around your Jeep’s oil filter will covered in oil. Worse than that is your Jeep’s starter will get covered in oil drippings. This will ultimately ruin the starter. If you look closer, you will see the seepage at the seams of the oil filter adapter. Once diagnosed, the only solution is to replace the O-rings.
What Jeeps Usually Have Oil Filter Adapter O-Rings?
The Jeeps that commonly have these oil filter adapter assemblies include: Jeep Cherokee (XJ) 1984-2001 and Jeep Grand Cherokee (ZJ) 1993-1998 with 4.0 liter inline six-cylinder engines. I have done this on my 1996 Jeep Cherokee (XJ) and my 1997 and 1998 Jeep Grand Cherokee (ZJ)’s. They are bone dry to this day.
Here is what you will need:
Wrenches/sockets – Rateheting wrenches are helpful
Breaker bar – To break the nut or bolt loose
Cheater pipe – For more leverage if needed than provided by breaker bar
Penetrating oil spray
Jack – If you need to raise the vehicle
Ramps or jack stands – If you need to raise the vehicle
Wheel chocks – If you need to raise the vehicle
Specialized Parts and Tools:
How Do You Change the Jeep Oil Filter Adapter O-Rings and Stop the Oil Leak?
The process is quite simple, but the secret is to drive the vehicle for about 20 minutes prior to starting the job. Yes, that is the key to the whole job. At this point, you are probably wondering why? The answer is that at the factory they apply red Loctite to the threads of the main bolt that holds the Jeep oil filter adapter assembly to the engine block. There are different level of thread locking dressing, but red requires heat the get the bolt loose. The heat generated from running the engine 20 minutes or so, loosens up that red Loctite thread dressing and will allow you to break that bolt loose to make the repair.
So, after you have driven for 20 minutes or more, carefully pull your Jeep up on to the ramps with your front tires, employ the parking brake, and place the wheel chocks behind the rear tires. Disconnect the black or negative battery cable for safety—especially since you will probably want to clean off your starter.
Consider doing an oil change when doing this job. Two reasons:
- You will have to top off a small amount of oil doing this project anyway, if you don’t do the oil change, and
- It is easier to handle the Jeep oil filter adaptor assembly without the oil filter on
It is up to you, but I highly recommend this approach.
Loosening the Main Bolt and Pulling the Oil Filter Adapter Assembly
Go under the Jeep from the right front on your back with your feet sticking out the front. Be careful, many components under the Jeep will still be hot from running it. You should see the Jeep oil filter adapter from below and will have access to fit the first tool (L-shaped T-55 Torx “star” bit) into the oil filter adapter. You want the L-shaped bit because the space between the oil filter adapter and the Jeep’s body is very tight and because you will want to put the long end into the 1” x 2’ steel pipe for leverage (using a pipe like this is called a “cheater pipe”). Once the bit is firmly in the adapter, push the pipe toward the front of the Jeep—“lefty loosy”. Push hard and it will turn. Once it turns give it another turn or two.
Once you have got it loose, switch to the smaller T-55 bit in a ratcheting wrench to speed up the loosening of the oil filter adapter bolt. It will eventually get to a point where it just spins—it can then be pulled out as whole assembly. I usually do this from the top of the Jeep’s engine bay to avoid getting oil drippings. Use a catch basin or bucket to catch any drippings.
Disassemble the Jeep Oil Filter Adapter and Remove the Old O-Rings
Once you have the Jeep oil filter adapter out of the Jeep, you can take it apart. There are three O-rings in the oil filter adapter assembly: a large one, a medium sized one, and a small one. You will find the large one is flat and brittle—it’s the culprit behind the oil leak. The other two O-rings will probably look okay—still round and soft. Regardless of their respective condition, they need to be replaced too.
Now is a good time to clean the Jeep oil filter adapter assembly. Use brake cleaner or engine degreaser. Once clean, dry all the pieces off and start the reassembly.
Reassembly of the Jeep Oil Filter Adapter
When going to reassemble the Jeep oil filter adapter, be sure to put some fresh motor oil on the new O-rings. Clean the area around the connection at the engine block with rags or shop towels. Use brake cleaner or engine degreaser if needed. Be sure to check and clean the mating surfaces if necessary. Finally, apply a little red Loctite the threads of the main, large bolt and carefully reinsert into the block. Turn the main bolt by hand to get it started and properly threaded. Be sure to realign the assembly in the same orientation it had when you removed it.
Now do everything in reverse order. Use the small E-55 bit with a ratcheting wrench to quickly tighten it, then switch to the L-shaped T-55 and the pipe to really tighten it down. Remember pull towards the rear of the Jeep now—“right to tight”.
Finishing the Jeep Oil Filter Adapter Job and Clean Up
If you took the earlier recommendation about doing any oil change, put the new oil filter on the adapter assembly and refill the oil. Then reconnect the battery wire to the battery, and then lower the vehicle off the ramps. Recheck the Jeep’s oil level and look for lacks from the adapter—tighten more if needed. Your Jeep oil filter adapter should now be good for another 100,000 to 200,000 miles.
Why is This Job Such a Pain?
Changing the Jeep oil filter adapter is a pain for three reasons:
- Tight space
- Special bit (T-55 Torx)
- Red Loctite
The tight space can be overcome by using two different Torx bits: 1) an “L” shaped and 2) a bit without the socket casing.
The special bit, Torx T-55 is a must, unless you have an older Jeep with a nut type top (I have never seen one).
Finally, the red Loctite from the factory means you need to heat it up, by driving the Jeep first.
While changing the Jeep oil filter adapter is a pain, it is a relatively easy job with the right tools, knowledge, and skills.
Is There an Alternative?
You might be wondering if there is an alternative to the Jeep oil filter adapter? Well, some people will remove the Jeep oil filter adapter and screw the oil filter straight into the engine block. While it can be done this way, I prefer to keep the system the way it came from the factory. The inconvenience of this job should only occur once or twice in the Jeep’s lifespan.
What Can be Done as Far as Maintenance?
Unfortunately, not much maintenance can be done. Once you have changed the oil filter adapter O-rings, it is just a case of waiting for the O-ring to start to fail again. The good news is that it may be 100,000 miles before that happens. Finally, you now have the tools and skills to quickly fix it