Why does this thing leak?

Messages
69
Location
collierville, TN
I was giving the jeep the look over today and the oil and all other fluids look good but i found something that worries me... I believe i have a slight rear main seal leak... My engine just fell out of warranty and now i have this to contend with... Ive changed a rear main on a 4.0 before but i really dont want to do it again to my jeep. What causes a rear main to leak? Are there any good "stop leak" additives that work? EEEEEERRRRRHHHHHHHHH! I need something more economical and trouble free! [Mad]
 

Al

Messages
19,200
Location
Elizabethtown, Pa
Who knows?? Lip seals depend on shaft contact and wear out either due to oil incompatability, dirt, incorrect installation,shaft runout etc. You could solve the problem (if your lucky) by going to an oil that tends to cause more seal swell. Possibly Maxlife or if you are desperate maybe Redline-being mainly an ester might help. I assume you can get to this one by just dropping the pan?? I know it still isn't pretty [Frown] Maybe Jeep adopted the Chevy philosophy of many years ago: "If the rear main leaks it must be a chevy"-seemed like it was built in.
 

higney85

Thread starter
Messages
69
Location
collierville, TN
thinking about running the auto-rx in there and tightening up the oil pan bolts (may be reason for slight leak) and maybe a 10w-40 and replace the sending unit... sound like the leak should stop?
 

higney85

Thread starter
Messages
69
Location
collierville, TN
parents said they wil help me pay for one before i go off to college in august but will most likely want to keep the jeep around for my sis to drive through HS. Ive already spent my own money rebuilding the entire jeep so i dont wanna just get rid of it and lose all i put into it. Back to topic though- the auto-rx stuff looks appealing to me and i really dont wanna install a new seal but if i gotta, i gotta. [Bang Head]
 

Patman

Staff member
Messages
21,989
Location
Oakville, Ontario
quote:
Originally posted by edwardh1: Or get a Japanese car. ALL my GM cars some bought new , leaked pans and valve covers NONE of my 4 Japanese cars over the years leaked
My mom has a 94 Probe GT (Mazda engine!) which leaked oil like crazy out the valve cover gaskets. No make is immune to leaks.
 
Messages
3,693
Location
Chattanooga, TN
IMO just keep an eye on it. Most seepages go on for years before they develope into enough of a leak to require repair, some even go away. In most cases they are not worth repairing if you look at the cost of oil versus repair. Only if it is seriously impairing the operation of the engine (possible low oil, really leaking) making a mess on the ground etc. it is not worth repairing. Keep an eye on it.
 

MolaKule

Staff member
Messages
21,699
Location
Iowegia - USA
Why does a seal leak? Two main reasons: 1. Wear on face - wear has removed enough material that pressure to hold back fluids has diminished. 2. Sludge attacks elastomers and creates microscopic cracks. As suggested by Spector and others, use some Auto-RX and only if the leak is like 1/4 pint per day or greater will you need to do a replacement. BTW, does sis like engines and wrenches? You might want to at least get her interested in the basics!
 
Messages
4,841
Location
Lakeville, MN
It leaks cause its a Jeep! My '88 Cherokee isn't leaking anything right now, but I'm sure something will start soon enough. Oh well... You may want to try one of the "high mileage" oils like Valvoline Maxlife. Some folks have reported solving leaking engines on some of these oils. Might be worth a shot...
 

higney85

Thread starter
Messages
69
Location
collierville, TN
well the sis is spoiled rotten so im sure if anything goes wrong ill haveta deal with it when i come home for visits from college or my parents will just pay to have it fixed. The leak is about 2 noticeable drops on the bottom of the bellhousing and so far (knock on wood) i havent seen any on the ground. Im thinking ill be running the 10w-40 and the auto-rx and hopefully things will be cool. [Cheers!]
 
Messages
12
Location
NJ
quote:
Originally posted by edwardh1: Or get a Japanese car. ALL my GM cars some bought new , leaked pans and valve covers NONE of my 4 Japanese cars over the years leaked
The Toyota 2.2L 4 cylinder is famous for leaks. They were used in the Celica, Camrey, and others. The cam seals harden and leak oil like crazy. I've seen as bad as 2 qts/1000 miles. The Nissan V6 motors are also known for their cam seal leaks. People talk like the Jap cars are immune to mechanical failure, that's just not the case. I've fixed many an oil leak on a Japanese motor.
 
Messages
378
Location
West Coast
1. It's a Jeep thing. The 4.0 rear main, at best, will only last about 100K before it leaks. 60K seems to be the norm though. 2. The 4.0 seems to like 15W-40 Delo or Delvac oil. Why...Idunno. It does quiet the piston slap that is common with these motors. It also keeps them very, very clean. 3. My 4.0 ZJ has leaked for about two years. About 2-3 drops per day. And still, with my one year drain intervals I don't have to add back a drop in between bi-annual filter changes. 4. I simply no longer worry about it. [Cheers!]
 
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