Jeep Enthusiast Forums banner

Leaky rear main seal on a 4.7

5K views 7 replies 3 participants last post by  Kevin616 
#1 ·
Hey gang,
I went to a car wash/quickie lube today and the guy said it looked like I had a leaky rear main seal. He tried to sell me a Lucas "stop leak" type of product. I was skeptical and didn't take the bait. When I got home I started looking at rear main seal repairs online and it averages between $600-800 to have it repaired.

I've had my wk since October and I know I'm behind in the oil change interval, but I've not needed to add any oil, nor have I heard any sounds to seem like an oil thirsty motor. This makes me think that the guy was just trying to sell me an unnecessary add-on to my bill, but I'm not sure.

I have very low miles, under 86k. Is this a common problem?
Is it an obvious thing to diagnose with just a glance?
Is the quickie lube guy just trying to sell me? (obviously, you cant see my wk, so its more a question of the odds.)

I was IM'ing Kolak today about a 2"BB and bilsteins, but if I need to do this repair, I'll have to put that purchase on hold.
 
#4 ·
The 4.7/3.7 family of engines don't often have leaking rear main seals, especially with such low mileage. However, the FRONT seal does tend to leak and because of the way the oil pan is designed the oil runs along the "lip" on top of the oil pan and backwards to the rear of the engine. When there's enough accumulation it drips along the rear of the engine. I've had a front seal leak on my 3.7 for quite a while but it's not enough to even notice between oil changes. Makes a small spot on the driveway and that's about it.

As mentioned above the valve cover gaskets may have a small leak that would show up at the rear of the engine but you'd typically smell burning oil from the drips on the exhaust if there is a leak there.

In short, unless you notice oil loss on the dipstick there's not much to worry about. Don't let techs at a quickie lube talk you into any kind of stop leak, otherwise known as 'stop running.' By the way, pay attention to oil change intervals and watch your oil level. The 3.7/4.7 engines tend to sludge up if the oil isn't fresh or up to the correct level.

Bob
 
#7 ·
The good news is the front seal is pretty easy to remove and replace - especially compared to the rear seal.

Double-check your water pump. Having coolant around the front main seal is a symptom of a weeping (and failing) water pump. There is no coolant that circulates around the front main seal - that seal only keeps oil in the pan and contains oil from the crankshaft oil journals. Coolant would come from above the harmonic balancer - likely from the weep hole on the bottom of the water pump (another relatively easy repair.)

Bob
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top