While having my 93 XJ I-6 auto inspected by the dealer, he diagnosed an oil leak as coming from the rear main seal. He suggested that it wasn't worth it to get it fixed, and suggested I just keep tabs on the oil level.
A few days later, I had an independant mechanic change the front differential fluid (dealer said there was water in there, but there wasn't- go figure). This mechanic said that the seal might leak a little oil for a time, but then catastrophically fail at an inconveniant time.
So, any ideas if I should have the seal fixed or leave it? At the moment it's slow enough that it's not even an annoyance.
Ill bet you 10 bucks right now that it isn't your rear main seal. Its your valve cover. Wipe your finger along the back of the head near the firewall. If its oily, there's your leak. If not, the rear main is a breeze to replace. The only hard part is cleaning the old stock original gasket.
If it leaves a puddle, then it could be the rear main seal, if it only leaves a drop or two then its the valve cover. That was my experience... everyone said it was my valve cover but there was much more oil on the garage floor than was coming down the back of the block. I don't know if I would call it a breeze as Kevin did, but its not too bad. I had the take the passenger side motor mount off to get the oil pan off. Then you have to be very patient when installing the new seal so as not to damage it. Good luck!
Approximately 11/25/03 22:38, Monte Castleman uttered for posterity:
Before changing anything, check along the sides of your engine block. The valve cover gasket is a very common oil leak, as the oil runs rearward and down, main-seal happy mechanics may misdiagnose it as a rear seal.
As for sudden failures of main seal, guess it could happen, never heard of it. And the seal is reasonably simple to replace anyway.
I didn't see any confirmation from the mechanic at all. What he said, according to the poster, was that it might leak a little for a while, then fail catastrophically at an inopportune moment. The mechanic may very well have given a backup diagnosis, but the original posted did not tell us of it. All we know for sure is that the dealership said the rear main was gone. We all know that this is a commonly mis-diagnosed problem, and we should not be surprised that the dealer might get it wrong.
Monte, Don't know what dealer you used but there's a place in Burnsville off Hwy 13 called Burnsville Off road that really knows there stuff about Jeeps and you can trust them. As you might guess I'm not real thrilled with the local Jeep dealers, Especially Park Jeep.
This is not a confirmation that the rear main in fact IS LEAKING. All it is, is a statement that if it is leaking, it can leak for a long time before it completely fails.
Despite all of this, we all know that the Valve Cover Gasket does a very good imitation of a rear main that has gone south. Before anything else is done on the rear main, it must be confirmed that the VC gasket isn't the real problem.
Then, if the rear main is gone, the repair should take about 2 or 3 hours for a shop, and 3 or 4 hours at home.
JD, I did indeed go to Park Jeep, not because I like them but because they were offering free vehicle inspections and I had the day off, so I figured I'd take it in and see if they turned up anything that needed to be dealt with before winter, having no intention of paying them to do the actual work. They quoted:
Replace Front differential fluid (contaminated by water) :
Replace missing exhaust clamp:
Replace rear main seal: 0
My regular mechanic, (the one I emailed you his name and address) wasn't available that day, so against my better judgement I called another place I was familiar with- an inner city outfit, and they quoted $45 for both 1 &
They're the ones that said the seal might suddenly fail, and quoted 0-0 to replace it. Previously this place had tried to tell me my drive chain needed replacement. My regular mechanic, who opened the transfer case in order to replace the seals, found nothing wrong with it.
Thanks for the recommendation. Might be good to see what someone who works on 4wd stuff all the time but is not a dealer has to say.
Everyone, I'm pretty sure it's not the valve cover gasket, since that was replaced a few months ago- It was obviously leaking oil on top of the engine. (Also replaced the O-rings on the filter adapter). I've not washed the bottom of the jeep since then, but the oil does appear to be fairly fresh, and looks like it might be coming from between the engine and the tranny. It's leaking enough to give the bottom of the tranny a good coat of lubrication, but is not really enough to drip onto the ground yet.
Why might the dealer think water got into the differential when it hadn't, or were they just putting me on? The fluid needed to be changed anyway, but I don't like being lied to.
Monte Castleman, Bloomington, MN to email, remove the "q" from my address
lubrication, but is not really enough to drip onto the ground yet.>
Then it's not worth worrying about. A certian amount of seepage is normal. The split main seal is is a rather weak design and can require frequent attention on some Jeeps, virtually none on others. ( My '94 YJ gets a new seal about every 20k miles.)
Drive a bit then pull/unscrew the plug and stick your finger in there. If it comes out white/foamy then you have water. If it comes out dry you don't have enough lube.
Draining and refilling diffs is easy to do although you may have to jack the vehicle up or remove the track bar to get at it. (Depends on vehicle)
Now that's an expensive load of bullshit.
2-3$ and a few minutes with a wrench. Some muffler shops will do this for a few bucks more if they even charge you at all.
This is a sure sign that your mechanic should be avoided and all other "suggested repairs" should be looked on with extreme suspicion.
Check behind the valve cover up top to make sure that's not what's leaking.
While the average wrencher can replace the seal, you have to be comfortable with the idea. But 550 sounds high.
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