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Oil leak from rear of engine


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So I finished swapping my engine in my 98 outback a couple weeks ago and noticed that I had a fairly sizable oil leak. After doing some research I read about the awful plastic oil separator plate that Subaru used, so I pulled the engine again to replace it, and sure enough, the plate was leaking.

 

I got it replaced, cleaned the surfaces and applied RTV, making sure to wait upwards of 26 hours for it to cure before I filled it with oil. But it still leaks!

 

At this point I’m stumped because I saw no other leaks from the main rear seal or the oil pan or anything while I was back there, and I don’t see oil leaking from the bell housing area (where I did see oil before), but it just seems to keep appearing on the cross member and dripping onto my driveway. I am stumped at this point and am worried that I’ll have to pull the engine again, which won’t be very easy since I’ve got school starting back up here soon

 

 

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Is it definitely motor oil? Mine has leaked stearing fluid where the rack connects to the lines up to the pump. It gets all over the crossmember and exhaust from there. Especially after having the motor out it could get disturbed.

 

You could get some UV dye and put some in your oil and use a blacklight to see what glows. I do it in the dark or near dark to make it easier. Run the motor for a few minutes for a big leak, or 15 to 30 for a slower leak, then get it on ramps and crawl around under there with the light.

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Is it definitely motor oil? Mine has leaked stearing fluid where the rack connects to the lines up to the pump. It gets all over the crossmember and exhaust from there. Especially after having the motor out it could get disturbed.

 

You could get some UV dye and put some in your oil and use a blacklight to see what glows. I do it in the dark or near dark to make it easier. Run the motor for a few minutes for a big leak, or 15 to 30 for a slower leak, then get it on ramps and crawl around under there with the light.

 

 

 

I mean I guess it could be, it certainly looked like the color of motor oil though. These cars take ATF as the power steering fluid though don’t they?

 

 

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ATF, yes.

 

New member and all, it's hard to tell what level of experience you have.

 

So, sounds like the easy way is to try the dye. I've seen the UV flashlights at the hardware store. I don't recall seeing them at the auto parts store where the UV dye is. Could be an opportunity for parts stores...

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ATF, yes.

 

New member and all, it's hard to tell what level of experience you have.

 

So, sounds like the easy way is to try the dye. I've seen the UV flashlights at the hardware store. I don't recall seeing them at the auto parts store where the UV dye is. Could be an opportunity for parts stores...

 

 

 

To be quite honest I’m kind of an amateur, this being the first engine swap I’ve ever done, but I do pick up things quick.

 

Also I just went out this morning to check the oil level and it was 3/4 of the way down the dipstick when it read over full yesterday. I’m so confused at what it could be now that I know it’s an oil leak. I did start reinstalling the engine only a little bit after I applied the RTV so could some residual oil have dripped on to the RTV and compromised it? That’s literally all I can think of right now.

 

 

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As long as the parts are clean when the RTV goes on, and you don't pressurise it before it cures, you'll be fine as far as that goes.

 

But that is a lot of oil missing.

 

In that case I would put the dye in and only run it about 3 to 5 minutes to mix it, and then shut it off and look for the dye.

 

As for the separator plate, you got the new design metal plate? Nothing could have happened to the rear main seal during assembly. The engine wasn't supported by the oil pan or valve covers during the work? There aren't that many places where oil can get out of the system.

 

Maybe you could take some pics under there to try to show what is most wet. Also, there is a little access cover on the top of the block passenger side looking back and down into the flywheel area. Can you find that and get a view inside there to see how wet it is?

 

I assume you are not next door to central AZ.

Edited by doublechaz
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As long as the parts are clean when the RTV goes on, and you don't pressurise it before it cures, you'll be fine as far as that goes.

 

But that is a lot of oil missing.

 

In that case I would put the dye in and only run it about 3 to 5 minutes to mix it, and then shut it off and look for the dye.

 

As for the separator plate, you got the new design metal plate? Nothing could have happened to the rear main seal during assembly. The engine wasn't supported by the oil pan or valve covers during the work? There aren't that many places where oil can get out of the system.

 

Maybe you could take some pics under there to try to show what is most wet. Also, there is a little access cover on the top of the block passenger side looking back and down into the flywheel area. Can you find that and get a view inside there to see how wet it is?

 

I assume you are not next door to central AZ.

 

 

 

I cleaned everything thoroughly and reapplied an ample amount of RTV *and* thoroughly cleaned the inside of the block around it so there was no residual oil around it. I then let it dry for 24 hours, filled it up before I reinstalled it, saw no leaks for ~5 mins, so I went to mate it up to the transmission. After I did that and a few other misc things I look down under again and there’s FRESH OIL IN THE SAME SPOT I HAD WIPED DOWN ON THE CROSSMEMBER. I am at my wits end with this leak and really do not know what to do. ca1da2fa63569bf84e3070d4a06fa015.jpg6aeaa51099c19af9ee461269a0e57619.jpg

 

What it does is stream down in that same spot every time and then gradually drip off of the underside of the crossmember. You can’t see the droplets because I had wiped it down before taking the photo

 

 

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The oil dribbles out even when you haven't run it? I ask because the exhaust seems disconnected in the shots. Without running, all the oil should be below the block to pan seam. Did that new very clean oil show up when you were refilling it? I'm thinking oil filler or driver's side valve cover damage. Maybe driver's side rear cam cover seal. That oil looks too clean to have been through the engine other than flowing from the filler down to the sump.
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You didn't state which engine you swapped in.

As doublechaz stated check the valve cover and rear cam seals on that side.

The new plate has an arrow on the upper left. You may have gotten a black bolt with red rtv already on it if you bought new bolts. The new plates will not seal with the old countersunk screw bolts.

The fsm diagram shows a tube with a squiggly line , this is RTV (or Fujibond) that should be applied to that part.

 

O.

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You didn't state which engine you swapped in.

As doublechaz stated check the valve cover and rear cam seals on that side.

The new plate has an arrow on the upper left. You may have gotten a black bolt with red rtv already on it if you bought new bolts. The new plates will not seal with the old countersunk screw bolts.

The fsm diagram shows a tube with a squiggly line , this is RTV (or Fujibond) that should be applied to that part.

 

O.

 

 

 

I did in my previous post on here about something, but I’ve got a 98 outback and I swapped the ej25d out of another 98 legacy. Same car basically, so it was just plug and play. As for the plate the squiggly line tube thing I thought was pointing to just the general plate, which I did RTV but I did not realize that the bolt with the arrow pointing to it needed the one with the red stuff on it, so that may very well be my issue. I did use new hardware that was included with the plate I bought.

 

 

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The oil dribbles out even when you haven't run it? I ask because the exhaust seems disconnected in the shots. Without running, all the oil should be below the block to pan seam. Did that new very clean oil show up when you were refilling it? I'm thinking oil filler or driver's side valve cover damage. Maybe driver's side rear cam cover seal. That oil looks too clean to have been through the engine other than flowing from the filler down to the sump.

 

 

 

I think you may be on to something there... I pulled the engine back away from the trans to look at the plate and... there’s no oil around it, but over by the drivers side valve cover there is in fact a big pool of oil. Not sure how much you can see from these photos but take my word for it, it’s there. c908385853a9ecc3842e5fb8f3b6c822.jpg

This is the crossmember from above. 58814c04693aa8ce0eb73ecec3110fc1.jpg

And this is over by the drivers side valve cover. a26681a4f1fc14d160be2f647d795d63.jpg

And then here you can see that around the plate it is the exact same as how I left it

 

 

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Also, the rear main looks clean. There looks like maybe a tiny bit of weeping from the drivers side rear wrist pin access or something, but not the source of the big wet spot.

 

Am I right that this oil is leaking without the engine ever running?

 

If it is leaking that much without running, there should be a visible hole. If that puddle is after you've run it, the cold PSI of the oil should be up around 80, so a lot will come out of an invisible hole, but there aren't many places that can happen.

 

A short list from memory would be front and rear mains, head to block, front and rear main galley accesses (front houses the oil pressure switch), cam seals and covers, oil filter, oil cooler lines if equiped, oil pump to block. I think that is pretty close to all the high pressure leak points.

 

Valve covers and spark plug tubes, pan gasket, oil separator, PCV, filler neck, and dipstick into pan is close to all of the low pressure leak points. Stuff related to the cams and crank could be argued to be low pressure leak points depending on sludge level in the drainbacks, and the size of the leak, but given I pumped out two quarts in 8 miles through the front main via a 3/4 inch tear, I would argue that they are more like a high pressure leak point.

 

So with that depth of oil coating the crossmember there should be a pretty thick golden layer somewhere above that. The slow weep points are the ones that are black with stuck on dirt and look dry.

Edited by doublechaz
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I can't see the #4 wrist pin cover in the shots, but it looks like that might line up with your wet spot. It's just to the left of the crank shaft inside the bellhousing (part #10 and #11 in the diagram). Or it might be coming from farther left like the back corner of the head which would be a cam cover or valve cover etc. Is there anything wet when viewed from above? What is the little black bit of broken plastic above the fuel line clamp screw laying on the crossmember? Also, what is the dry metal thing in that same shot that runs down and under the block? Edited by doublechaz
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Isn't the plate.

Clean the access plate area #11 that Doublechaz mentioned with carb cleaner and check the plastic half moon on the back of the head. It may be chipped and leaking past it when running.

 

O.

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Hey there, sorry for the absence but I think I fixed the issue :). I put rtv around the entire perimeter of the valve cover, and then put some form a gasket stuff on the outside of it for a secondary layer. I test drove it last night when I finished putting it back together and it seems to not be leaking! Fingers crossed it stays that way. Thanks for all your help!

 

 

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