How long do rear main seals usually last?

Rockinrod

Rockinrod

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Can someone who has owned Jeep Wranglers for a long time, can you tell me on average, about how long these rear main seals normally last, give or take...We do 99% city driving, if that matters...I'm keeping an eye on something suspicious now down below near this two grommets near the oil pan...

Thanks,

Rodney
 
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What year & mileage? I've put probably 200k miles on 3 different JK's. Never had a rear main seal leak on a 3.8 or 3.6. However, the 3.6 is known to have the oil cooler leak which can look a lot like a rear main seal issue.
 
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2017 which I purchased March 2017, it has 50,501 on it...Not even 4 years old yet. Just did the oil cooler last month and one 02 sensor, and drivers side valve cover gasket last week...Seems like a lot happening on it all of a sudden!
 
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Sorry, I do recall you posting about some of this before.

If the oil filter cap was torqued too tight, it could have cracked the housing. Take a long dowel and put it in the valley and check for oil. Better yet, get a cheap Harbor Freight inspection camera and take a peak.

I'm sorry you've had a bad run. Hopefully, this will be the end of it and you can enjoy your Jeep.
 
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JerryD said:
Sorry, I do recall you posting about some of this before.

If the oil filter cap was torqued too tight, it could have cracked the housing. Take a long dowel and put it in the valley and check for oil. Better yet, get a cheap Harbor Freight inspection camera and take a peak.

I'm sorry you've had a bad run. Hopefully, this will be the end of it and you can enjoy your Jeep.
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I just got this inspection kit today. Already been under it poking around. Looks pretty good so far..That's a stupid place to mount an oil filter, IMO...Should be on the side and bottom end, like everything I've had since 1969...

Inspection kit.jpg
 
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Man, this is such a relative question. Some will last over 200k, others will fail before 100k. I'm not sure there is any rhyme or reason to it. I would however replace it if the transmission were to ever need to be dropped (i.e. clutch replacement).
 
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Been my experience owning a crap load of vehicles over the past 50 years never know.... No set answer of course. My intent was to find out if anyone here had ever had a failure prematurely...That was it...I got these two weeper holes here on the bottom with tiny trace of oil inside there. May be nothing. I'll keep an eye on it...Oil cooler and valve cover gasket looks okay still...

Thanks
 
Chris said:
Man, this is such a relative question. Some will last over 200k, others will fail before 100k. I'm not sure there is any rhyme or reason to it. I would however replace it if the transmission were to ever need to be dropped (i.e. clutch replacement).
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Yes I will agree with this, knowing my luck i'd just put a new clutch in and them a month later the main seal would start leaking.
 
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Rockinrod said:
Been my experience owning a crap load of vehicles over the past 50 years never know.... No set answer of course. My intent was to find out if anyone here had ever had a failure prematurely...That was it...I got these two weeper holes here on the bottom with tiny trace of oil inside there. May be nothing. I'll keep an eye on it...Oil cooler and valve cover gasket looks okay still...

Thanks
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I remember back in the old days the engines when they got close to 90,000 miles on them they would start leaking from the seals and you'd get a little oil burning and i'd just put some heavier oil in them.

You could put the next weight up on the oil and see if it would stop. Is there synthetic oil in the engine, it will make leaks before dino oil.
 
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BLACKJKU said:
Are they putting synthetic oil in it?
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I'll look at the paperwork. I save all the maintenance receipts...I'm on 5,000 mile oil change intervals. Doesn't say, all it says is 5W20 weight and the PN. I don't think it is though. I was ask this question after I purchased this Jeep, about what oil I wanted to use, and I said no to synthetic...I didn't like the idea of having oil in an engine for 10-12K miles..Too long in my book. I'm old school from the 60's and 70's...

Rodney
 
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It's ok to have the oil in that long just change the filter about half way. In my Diesel trucks I go around 20,000 miles on a oil change and just change the filters every 5,000 miles. I did a oil sample at a lab to check my oil at 15,000 miles and they said the oil was still good for more miles. The oil doesn't break down it just gets dirty.

If they are putting synthetic oil in that can cause a drip, I use synthetic oil in one of my Diesels and it drips sometimes.
 
BLACKJKU said:
It's ok to have the oil in that long just change the filter about half way. In my Diesel trucks I go around 20,000 miles on a oil change and just change the filters every 5,000 miles. I did a oil sample at a lab to check my oil at 15,000 miles and they said the oil was still good for more miles. The oil doesn't break down it just gets dirty.

If they are putting synthetic oil in that can cause a drip, I use synthetic oil in one of my Diesels and it drips sometimes.
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Like I said previously, I was ask back in 2017 if I wanted to use synthetic, I said no...So, I'm assuming they stayed with the same oil from day one.
 
My 2014 had a rear seal leak at around 65 or 70k. Was very minor and, if not for the very small drops on my nice, clean concrete driveway, I might have never noticed.
 
My neighbor told me ( a senior tech for Chrysler) the rear seals have been known to fail on the JKs early. I replaced mine early since I had being putting in a racing clutch anyways. Just saying.
 
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