Changing the oil pan seal...

Just had an oil leak start up on me the other day, it appears to be leaking out of the back of the engine oil pan and using the little angle near the drain plug as a 'drip tip' and leaks down onto the exhaust pipe from there where it'll burn, should I worry about my Jeep blowing up?

I'm looking into changing out the seal for the oil pan so I consulted my Jeep shop manual and it says for my 1990 XJ 4.0 I'll need to remove the exhaust, the starter, harmonic balancer cover, remove the motor mount and lift the motor up, is all that really nessecary or is there a better& faster way to change it out? When I've got the oil pan down what should I clean out sludge wise?

Thanks for the help

~Zoro~

The only thing that I took loose was the head pipe because on my old motor, some jerk ran the pipe right under the pan really close, but the stuff was not an issue, even with a three inch lift and 235/75/15's. And, yes, you should clean the pan out, but lokk at what is in it before you just wipe it out. That stuff can tell you alot about the motor. By the way, go ahead and change the rear main seal, because you will probably have to pull the pan again in a couple of months, anyway ( the 4.0 has a habit of showing you something to fix, and then showing you something else to fix in the same area a little bit down the road).

Zoro said:

I'll need to remove the exhaust, the starter, harmonic balancer cover, remove the motor mount and lift the motor up,

~Zoro~

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Not the harmonic balancer, the flexplate cover. The balancer is on the front of the crank.

If the Jeep is stock height you'll have a hard time getting the pan out. Either motor goes up, or axle comes down. Above 3" it's not bad, if the suspension is at full droop. I've always been able to leave the exhaust in place, but it's tight. (4.0)

Zoro said:

Just had an oil leak start up on me the other day, it appears to be leaking out of the back of the engine oil pan and using the little angle near the drain plug as a 'drip tip' and leaks down onto the exhaust pipe from there where it'll burn, should I worry about my Jeep blowing up?

I'm looking into changing out the seal for the oil pan so I consulted my Jeep shop manual and it says for my 1990 XJ 4.0 I'll need to remove the exhaust, the starter, harmonic balancer cover, remove the motor mount and lift the motor up, is all that really nessecary or is there a better& faster way to change it out? When I've got the oil pan down what should I clean out sludge wise?

Thanks for the help

~Zoro~

Click to expand...

Is your jeep lifted? If so your pan might slide out without lifting the motor.
Another way to potentially do it is to drop the axle (might turnout to be a lot less work that way).

Do a search for "Rear Main Seal" with my moniker, and read what I've done. I've done this with and without lift, and you won't have to tear down as much as you think...

Sorry, but I just don't feel like typing it all again right now. I've covered it a few times, so you shouldn't have to look too hard.

Yea, I say change the rear main while you're there. Shoud only add about 15 minutes to the time you'll spend under your truck, and you'll be there anyhow...

5-90

If is not lifted, you might try disconnecting the sway bar links at the bar, then block the back wheels on front and back then raise the front end and set it on stands. That should give enough height to pull the pan. Set the chassis, not the axle, just leave it touch with the ground.

For the meantime is there any kind of oil additive like they have for radiators that I can add to the oil that will stop the leaking until I can get it fixed? It's draining 2-3 quarts every other day...

~Zoro~

No need to raise the motor or disconnect your suspension. I have a stock XJ and was able to get it out by letting the suspension hang. Yes, not exactly easy, but I would do it again that way. The only thing I might do different is remove teh starter this time.
BSD

It's leaking well over a quart per day now so I can't drive it anymore, I climbed underneath today &looked at where it's coming from, it appears to be coming out from in between the engine and the transmission. I noticed there's a little gap on the bottom side but on all the other sides the engine and transmission are flush with each other, is this normal?

I'm guessing that I'll have to drop the trans&transfercase just to get at the gasket so will there be any special tools required since it looks like I'll be un-doing some u-joints? Also how long shold I expect this to take and is the gasket expensive?

Now I get what they mean by Just Empty Every Pocket...

~Zoro~

Zoro said:

It's leaking well over a quart per day now so I can't drive it anymore, I climbed underneath today &looked at where it's coming from, it appears to be coming out from in between the engine and the transmission. I noticed there's a little gap on the bottom side but on all the other sides the engine and transmission are flush with each other, is this normal?

I'm guessing that I'll have to drop the trans&transfercase just to get at the gasket so will there be any special tools required since it looks like I'll be un-doing some u-joints? Also how long shold I expect this to take and is the gasket expensive?

Now I get what they mean by Just Empty Every Pocket...

~Zoro~

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Did you read any of the responses?

Did any of them mention dropping the t-case or transmission? No.

Go to jeepin.com and read the rear main seal replacement write-up. Follow it like the others said and replace the rear main while your in there.

Have fun!

You do not have to touch the trans/ x_case for this except to maybe pull the inspectiotion plate off. It is the piece of stamped steel held on by 3-4 bolts between the motort and the trans. It is not a hard thing to change the rear main seal or oil pan gasket, the shops just want you to think that it is, so they make it sound oh, so complicated. The average(?) person with a little capability can do this in about 2-3 hours. the biggest pain is getting the upper half of the rear main out, and lining up the new pieces just right so they don't leak. This means, when you slide the upper piece into place, leave a little bit of it sticking down from the block, then match your offset with the piece in the bearing cap. If you take both pieces and hold them together to make a circle, it will leak, but, if you turn the circle just a little(3/16"), it will not leak. This is looking at the pieces with the 2 halves touching on the horizontal plane. Turn it a little, and no leak. Also, when you slide the top piece into place, lube it with a little liquid dish soap. It works wonders for installation. Look in the mech. book for any pictures you may need, doesn't have to be a jeep book, as a good source for pics., look at a chevy book

I have a leak too but not that bad. I get about 10-15 drips a day. Should I change my oil gaskets now or wait until they get worse?

-CRACKER

Depends: feel like doing it now, or later? Either way eventaully you will have to change it, but if it does not get much worse, then I would let it fly for now. All of my jeeps leak a little oil ( actually, they don't leak, they just mark their territory, kind of the way that a dog marks his turf. LOL )

ren said:

Depends: feel like doing it now, or later? Either way eventaully you will have to change it, but if it does not get much worse, then I would let it fly for now. All of my jeeps leak a little oil ( actually, they don't leak, they just mark their territory, kind of the way that a dog marks his turf. LOL )

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Thanks! I will let it fly for a little while. I picked up the big seal yesterday and I just happened to ask the service writer at the dealership 'how much to install this on a '94 XJ?' and he asked me what an XJ was, a Jaguar? Go figure. Then he quoted me $500. I started to laugh and he got pissed. Oh well. I'll change it my self when I get bored.

-Cracker

Before you dive into this project, let's get our terminology straight here:

The "oil pan seal" is not a seal at all, but is a GASKET that goes between the oil pan and the bottom of the engine block. It's changed by, obviously, removing the oil pan.

The "rear main bearing seal" is a true SEAL that surrounds the rear of the crankshaft where is exits the engine block. This seal must be replaced by first removing the oil pan, and then removing the rear main bearing cap. There are good write-ups that other posters have pointed to on how to do this.

Judging by your leakage rate, you have a worn rear main bearing seal, and just replacing a gasket on the oil pan is NOT going to solve the problem.

Sorry if this is obvious to some, but I was confused by the term "oil pan seal", as there is no such thing.

while on the subject oil pan gaskets and rear main leaks you might check your oil filter mount. My 93, after changing the above mentioned, still had a leak that presented in the same place. The O-rings in side the 90 degree elbow that mounts to the block were leaking. $.90 and 10 min dry as a bone (thanks Old Man)

AZ Jeff said:

Before you dive into this project, let's get our terminology straight here:

The "oil pan seal" is not a seal at all, but is a GASKET that goes between the oil pan and the bottom of the engine block. It's changed by, obviously, removing the oil pan.

The "rear main bearing seal" is a true SEAL that surrounds the rear of the crankshaft where is exits the engine block. This seal must be replaced by first removing the oil pan, and then removing the rear main bearing cap. There are good write-ups that other posters have pointed to on how to do this.

Judging by your leakage rate, you have a worn rear main bearing seal, and just replacing a gasket on the oil pan is NOT going to solve the problem.

Sorry if this is obvious to some, but I was confused by the term "oil pan seal", as there is no such thing.

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Thank you for the clarification. I did more research and I think you are correct that it is the rear main seal. I can live with the little drips for a while until I get bored enough to fix it. I will hold onto the gasket until then.

Thanks!

The leak started to get really bad and would leak a quart an hour so I had somebody rev the motor while I watched & it turns out that it was the oil pressure sending unit, it went and was leaking REALLY bad and the oil was dripping down &catching wind as I drove so it looked like it was coming from somewhere it wasn't, replaced the sender with a bolt, good for now...

Zoro said:

The leak started to get really bad and would leak a quart an hour so I had somebody rev the motor while I watched & it turns out that it was the oil pressure sending unit, it went and was leaking REALLY bad and the oil was dripping down &catching wind as I drove so it looked like it was coming from somewhere it wasn't, replaced the sender with a bolt, good for now...

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That makes more sense. Even a badly worn out rear main seal would be hard put to leak that much oil, and similarly, a bad oil pan gasket, though it can really gush, will slow down once the level is a quart or two low. My leaky main seal, which leaves a visible puddle whenever I park and sprays enough oil behind me to make rear window wiping a joke still doesn't lose more than a quart every 500-1000 miles (better on long trips).

davelbert said:

while on the subject oil pan gaskets and rear main leaks you might check your oil filter mount. My 93, after changing the above mentioned, still had a leak that presented in the same place. The O-rings in side the 90 degree elbow that mounts to the block were leaking. $.90 and 10 min dry as a bone (thanks Old Man)

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Good point, as the 4.0 seems to leak from that spot and the oil goes & accumulates in the area between the motor and transmission so definetly check. That oil flter elbow bolt is ungodly tight though.