Rear main seal leaking, advice?

[oceanstate88]

Hello everyone - need some advice here if you can - the 2001 4runner 3.4 auto 4x4 with 195k is leaking motor oil, looks like it may be rear main seal. Not bad yet but I know these things don't get any better as time goes on. I asked a mechanic about replacement and he said that with 'that many miles, the main bearings are worn and the crank moves around, so a new seal won't stop the leak, not worth it.' Ok, now what? I'm not too excited about using a Stop-Leak type of additive because I've read that they cause their own problems...should I just go with a High-Mileage oil like Maxlife and hope for the best? Is the mechanic 'full of it"?

 

[agloukhoff]

The mechanic is not really right that the seal won't stop the leak.

It may. In fact, it probably will.

But with the labor that is invovled, I am unsure I would bother if that was the only issue and it's a minor leak. It doesn't make financial sense unless you have already invested money into the engine itself.

So unless you just put on a new TB kit, new heads or something - I'd not fix it.

It would be infuriating to fix the leak only to have the head gasket go in 10k.

If you DO have a lot invested in the engine and know that it is in very good shape aside from the leak - I'd still wait. But I would replace the main seal and the flexplate since I'd be down there anyway.

In other words - keep driving till the engine has another issue or needs another major service. Then figure out if you want to fix the engine or flat out replace it.

 

[Richard808]

My thoughts on it is your mechanic has a valid point. However the clearances for the crank journals and bearings are somewhere in the thousanths of an inch or something like that. I dont know the specs off hand. The crank will rotate on the oil in this tight clearance and when you shut off the engine it will be able to fall or move down some now that the oil isnt pressurized.
The seal itself is flexible and should be able to allow some movement and still seal off oil. Over time the seal dries out and cannot flex as it could when new. If your bearings are worn, Id imagine it may not last as long but especially since yours is just starting to leak. Id put a new one on personally. Or just top off the oil as needed. To do a full rebuild for a rear main leak is definetely not worth it. And I wouldnt use any stop leak myself either.

 

[agloukhoff]

Do not use stop leak. If you do - you WILL ruin your oil cooler.

4Runners do not have a conventional oil cooler, but a funky oilcooler that uses your coolant and will clog easily with stopleak.

They're hard to find used unsludged and $400 from a dealer.

 

[theizzardking]

yeah i'd just leave it and possibly just try running a heavier motor oil, i have had a small main rear leak since i bought the truck... i knew it was there but bought anyways as it was only a slight leak and i'm losing an almost unnoticeable amount over a 3k~4k oil change period, imo it really comes down to how much your want to spend or if you want to do the work, if you got the time,skills,equipment and a spare car for a bit to do the work yourself I'd probably fix it as the seal is cheap..it's just hard to get to...
i decided from day 1 to keep an eye out for another engine to pick up and just swap when this one goes, but since it's not puking oil and more like seeping, it should last for years as is ,provided i check the oil occasionally ..... that's my view on it at least, i don't see the point in paying a shop 1k+ to pull the engine to drop in a seal....might as well pay the 1.5k to install a whole new motor....

 

[Diagram14]

There are a lot of mis-diagnosed "rear main" leaks on the 3.4 being that just about any oil leak on that motor will run off the back and down the bell housing. The most common fakeout seems to be from the valve covers.

Im not saying that its not your rear main but I would want to be certain before I spent a whole bunch of time contemplating whether or not to drop the tranny. Especially if all I had to do was pop the hood (much easier).

Look underneath and if there is oil running down the side of the bell housing rather than just dripping out of the bottom then its a different hole youre looking for.

 

[BeachWagon]

There are a lot of mis-diagnosed "rear main" leaks on the 3.4 being that just about any oil leak on that motor will run off the back and down the bell housing. The most common fakeout seems to be from the valve covers.

Im not saying that its not your rear main but I would want to be certain before I spent a whole bunch of time contemplating whether or not to drop the tranny. Especially if all I had to do was pop the hood (much easier).

Look underneath and if there is oil running down the side of the bell housing rather than just dripping out of the bottom then its a different hole youre looking for.

This was exact problem once before.... then I spit a plug... turned into a full rebuild..... Runs great now:dizzy:

 

[Victor]

I had a rear main seal leak, the 4Runner had almost 300 Kilometers but ran great otherwise. Took it to Toyota and they replaced it, and it's been great since! It's not uncommon to see these leak, fix it!!

 

[gannonrt]

The rear main seal cost approximately 50 bucks and a tranny jack from Harbor freight costs approximately another hundred bucks. If you have a spare vehicle and some excess time this would be a great learning experience to replace the real main seal. I did it when I replaced my clutch. Can't tell you what it's like to drop an automatic transmission though since mine is five speed.

 

[agloukhoff]

The rear main seal cost approximately 50 bucks and a tranny jack from Harbor freight costs approximately another hundred bucks. If you have a spare vehicle and some excess time this would be a great learning experience to replace the real main seal. I did it when I replaced my clutch. Can't tell you what it's like to drop an automatic transmission though since mine is five speed.

Unhooking the auto trans from the engine is going to be a real pita.

He'd need to get the engine/trans bolts off. Then deal with the flex plate bolts. THEN seperate the two.

It's not a fun job. If he doesn't have the flex sockets and extensions to get to the top 2 bellhousing bolts, he'd need those as well.

It's just not worth doing unless there is other stuff to fix.

Think of the oil leak as rust prevention....

 

[4Runner-Newb]

Thank you

There are a lot of mis-diagnosed "rear main" leaks on the 3.4 being that just about any oil leak on that motor will run off the back and down the bell housing. The most common fakeout seems to be from the valve covers.

Im not saying that its not your rear main but I would want to be certain before I spent a whole bunch of time contemplating whether or not to drop the tranny. Especially if all I had to do was pop the hood (much easier).

Look underneath and if there is oil running down the side of the bell housing rather than just dripping out of the bottom then its a different hole youre looking for.

You don't know how much of a headache (well, you probably do) you just saved me, man. I took your advice and sure as shit there's oil all over the op, front and bottom of the bell housing. Seriously.. THANK YOU!

 

[reelamin]

Personally....how much is it leaking? I'm being serious...if it has some/several drips when it's parked or your adding a quart every 2k I would not touch anything. Nothing better for rust prevention...cleans off easy when needed, and you freshen your oil up a few times. If it's living a visible puddle or you can watch it drip when running...that might require some repair work.

If you feel compelled to fix it. I would verify it's a rear main and not coming off the top of the engine. (Valve Covers)

 

[99 Problems]

Hello everyone - need some advice here if you can - the 2001 4runner 3.4 auto 4x4 with 195k is leaking motor oil, looks like it may be rear main seal. Not bad yet but I know these things don't get any better as time goes on. I asked a mechanic about replacement and he said that with 'that many miles, the main bearings are worn and the crank moves around, so a new seal won't stop the leak, not worth it.' Ok, now what? I'm not too excited about using a Stop-Leak type of additive because I've read that they cause their own problems...should I just go with a High-Mileage oil like Maxlife and hope for the best? Is the mechanic 'full of it"?

I know I have a RMS leak as well and I have reason to believe my bearings are starting to wear. I also am unsure of what to do since I;ve just rebuilt almost everything else on the truck and bought new tires, etc. (about 12,000 CAD) Do you get a chattering while accelerating under 1500 rpms? Any advice from anyone would be great!

 

[99 Problems]

My valve covers are leaky and I have to top off about a quart every 1000 miles. It doesn't leave puddles (if it does they're very small and rare). It seems to lose more oil when I'm driving at higher speeds on longer trips.

I'm debating getting this issue fixed but I think I have a bearing that's starting to go. A slight chatter at low RPMs while accelerating. Trying to figure out my best route.

 

[mtbtim]

My valve covers are leaky and I have to top off about a quart every 1000 miles. It doesn't leave puddles (if it does they're very small and rare). It seems to lose more oil when I'm driving at higher speeds on longer trips.

I'm debating getting this issue fixed but I think I have a bearing that's starting to go. A slight chatter at low RPMs while accelerating. Trying to figure out my best route.

Just do the Valve Cover gasket job and stop the leak. It's not a hard job but it is time consuming and will cost you some money. Here's a video tutorial you can follow:

<iframe width="560" height="315" src="https://www.youtube.com/embed/N5fAXAuGozI" frameborder="0" allowfullscreen></iframe>

 

[4Runner-Newb]

I resurected this post to say thanks to a guy that said to look at the head gaskets before assuming it was a RMS leak, which for me looks to be the problem Hopefully whoever inquires on this thread gets the help they need but, the original poster I think has long been rid of his problem since the original post date of this thread was in 2013 . Sorry for causing any confusion. :hello:

 

[99 Problems]

Just do the Valve Cover gasket job and stop the leak. It's not a hard job but it is time consuming and will cost you some money. Here's a video tutorial you can follow:

<iframe width="560" height="315" src="https://www.youtube.com/embed/N5fAXAuGozI" frameborder="0" allowfullscreen></iframe>

Love Tim and Sean's videos! lots of great topics! I've gotten more and more confident with doing my own work but this looks like something out of my comfort zone. Maybe not. How long would you expect a professional would take?

 

[mtbtim]

Love Tim and Sean's videos! lots of great topics! I've gotten more and more confident with doing my own work but this looks like something out of my comfort zone. Maybe not. How long would you expect a professional would take?

An experienced mechanic would probably whip this out in a few hours but I'd bet dollars to donuts you would do a better job because it's your rig and you care more than the mechanic racing to get to the next job. Plus, shops charge big coin for this.

If you watch the video, it's really not a complicated job. Just start early on a day off and knock it out. And, you'll have a serious sense of accomplishment when you're all done. Save yourself some money and take on the challenge.

 

[19963.4lsr5]

I have my engine out and am thinking about replacing the rear main even though it's not leaking and looks like sometime in the past it was done before. If I do it will be when I remove the engine from the engine stand.......


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[manualdr5]

Chattet at low rpms could be a heat shield.

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