[bike2work]

Hi guys,

I wonder if this rear main seal is leaking, if it is, how bad it is?. Please see pictures. After reading people talking about NOT to replace RMS if not leaking as many people experience leak with newly installed seal, I got pananoid. Also, this guy says his seal is not leaking but based on his picture, it looks like mine: Oil Separator Plate ~ Subaru Legacy Outback ~ BeerGarage.com (first picture of his page).

Also, it seems to me that the oil separator plate is not that bad, compare with other online pictures?
But I will change the oil separator plate anyway. It is the RMS that scares me.

So what would you say and recommend?

Thanks!

 

[1 Lucky Texan]

:lurk:

 

[bike2work]

I guess no one can be sure, just like I. I would ahead NOT touching it. I figured if it is leaking, it is probably very minor. If I replace I wouldn't be sure about the outcome.

 

[gbhrps]

bike2work,

I will not claim that this is exactly your issue, but ... I may have a solution that solves your problem.

15 years ago I had small puddles of oil on the garage floor, all about 2 inches in diameter, after every run with my 1990 300ZX. At no other time was there a visible leak of oil anywhere. It drove me crazy for two years, and I figured I would have to bite the bullet and drop the exhaust, tranny and clutch assembly to change out the rear main engine seal.

I bought a new rear seal, and just before I was getting serious about doing the job, I read a post on TwinTurbo net forum about a fellow owner who solved his leak by replacing the PCV valves (these cars have two PCV valves, one on each bank). He theorized that when the PCV valves quit working, crank case pressure built up enough to force oil out the rear main crank seal. I immediately bought two PCV valves, changed them, and never again experienced the oil leak.

I owned that car for 27 years, and sold it about a year ago, still with no more rear seal leak.

Is it worth your changing the PCV valve to see if it cures your leak?

Gene

 

[bike2work]

Thank you Gene!

I did change PCV valve sometime back, with an OEM one. I don't remember exactly mileage, but since my differential was toast I don't think I drove much after the change.

Hopefully those "oil leaks" was before the change. And hopefully, it will cure the problem. Your post gave me confidence that the RMS was OK.

 

[johnre]

It does have somewhat the look of a baked on old oil leak.

Now that you know to watch out out for it, just clean up this area and periodically inspect it for anything new.

 

[idosubaru]

a lot of them look like that and are benign - though it does appear to have maybe a little more build up than average around the 20 degrees or so circumference around 6 oclock. but it's pretty normal for them to have very light debris adhesion down low or the edges from light wetness - but no leaking.

i would replace it with a new Subaru OEM seal. if you're careful it's fine.

The rear main seal isn't less reliable or more risky - it is less forgiving of installation variances.

i've sort of hacked away at cam and crank seals before, taken chances, etc because i've done so many i can push the limits, etc. don't do that with rear main seals.

First - be sure to have something for seating the seal and don't "walk it in" - you can do that with other seals (i realize it's not recommended but it "works" if you've done enough). don't do that with the rear mains.

Go careful and buy two or three of them for practice or insurance so you're not so terrified of the first one or desperate to install it if you bunk it up. you can return them.

 

[bike2work]

@johnre
That's the plan.
@idosubaru
What you pointed out (RMS needs to be careful) is what I am afraid of. Also I think on this forum people have the theory
that over the time, new seal and the hole do not match perfectly. The hole gets bigger, sort of. It is a theory so could be wrong. But the risk is too high having to take transmission or engine out, if new seal is worse.

What do you suggest "something for seating the seal"? I was initially just thinking maybe some pipe fitting that I used for cam seals or maybe some other seals.

 

[idosubaru]

Cam and crank seals don?t have wear issues. the rear main has a much larger ID and circumference so the metal to seal interface is seeing higher speeds and far more mileage considering much greater circumference ?length? passes over any given point with each revolution than happens with any other seals on the vehicle. So if any would sustain compromising, maybe it would be that one.

That being said are you at 300,000 miles? - where are you seeing this information - can you link to it? do you see any Subaru shop owners or well versed people saying this?

Cams are way too small. You?ll need a much larger diameter installer.

I stack old rear seals together as a spacer/installer.

Probably some PVC pipe and google it, measure the diameter of the rear main.

 

[1 Lucky Texan]

Cam and crank seals don?t have wear issues. the rear main has a much larger ID and circumference so the metal to seal interface is seeing higher speeds and far more mileage considering much greater circumference ?length? passes over any given point with each revolution than happens with any other seals on the vehicle. So if any would sustain compromising, maybe it would be that one.

That being said are you at 300,000 miles? - where are you seeing this information - can you link to it? do you see any Subaru shop owners or well versed people saying this?

Cams are way too small. You?ll need a much larger diameter installer.

I stack old rear seals together as a spacer/installer.

Probably some PVC pipe and google it, measure the diameter of the rear main.

It would be great if you could make a video of a couple seal jobs. I've never done it and avoided the job on my WRX's first timing belt service. Figured they weren't leaking but might start if I fat-fingered the job.

 

[idosubaru]

Oh my, no time for videos here. Any on google? Seals are intimidating, there?s some ambiguity involved.

 

[1 Lucky Texan]

I need to check youtube - probably some there.

 

[KSKarl]

Back to the OP. I don't think that's enough oil to worry about. You may see as much or more after changing the seal. Just clean off the old dirt, run it, and check it when you change oil.

 

[bike2work]

@KSKarl
Thanks for your input. Yes that's the plan now.
@idosubaru
Sorry I did not bookmark the link(s). But I remember also people remedy this situation with some kind of sleeve called microsleeve

 

[jdim88]

I need to check youtube - probably some there.