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Subaru Seperator Plate Explained

In the Mid nineties Subaru went from an all aluminum Seperator plate to a plastic one, no doubt to save material cost. The plastic ones tend to crack over time and leak. The aluminum units are not available but Subaru has an updated kit made form stamped steel.

If you are having repairs made to your Subaru or are taking the engine out for any reason, this is a good thing to look into replacing while you are at it.

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39 Responses to Subaru Seperator Plate Explained

  1. Terry Boyer June 7, 2010 at 2:43 am #

    Excellent explanation on the “separator Plate. Two quick comments: Did I miss what year Subaru started using the steel separator plate as OEM?? Secondly, If something is worth saying, please say it slow enough for your audience to catch every word.

    Thanks for another great Preventative MX tip.

    Terry

  2. Justin Stobb June 7, 2010 at 5:12 pm #

    Terry,

    Your point is well taken, Subaru Started implementing the Aluminum plate in 2000, and then went from Aluminum to Stamped steel around 04 I believe.

    Justin

  3. Tom McDonald June 9, 2010 at 4:40 am #

    Very interesting explaination on the plate, cover and vapor knob changes in newer engines.

    • JOE CLIENT April 15, 2013 at 1:37 am #

      THAT OIL SEPARATOR PLATE SHOULD HAVE BEEN MADE OF STAMPED STEEL FROM THE BEGINNING.HOW COULD A AUTO MFG MAKE A CRITICAL ENGINE PART OUT OF PLASTIC, SPECIFICALLY WHEN IT IS DIRECTLY AGAINST A HOT ENGINE AND HOT OIL CAUSING IT TO WARP AND LEAK OIL DIRECTLY ON TO THE EXHAUST SYSTEM.
      IT HAS BEEN A MAJOR HEALTH ISSUE FOR PEOPLE WHO CANNOT AFFORD TO SPEND $1200.00 TO REPLACE A $20.00 PART,AND ARE FORCED TO BREATH IN THE BURNING OIL THROUGH THE HEATING AND AIR CONTD SYSTEM.SUBARU SHOULD HAVE HAD A RECALL ON THIS VERY SERIOUS ISSUE TO REPLACE THE PLATE AT THEIR COST.
      SHAME ON YOU SUBARU.SHAME SHAME SHAME ON YOU.

      • Justin Stobb April 15, 2013 at 6:59 pm #

        On your key board all the way to the left and three up from the bottom is a button that says “CAPS LOCK”

        OTHERWISE PEOPLE THINK YOU ARE YELLING AT THEM AND REALLY DON’T WANT TO DO ANYTHING BUT PRESS DELETE.

        BY THE WAY ANYONE CHARGING YOU 1200 TO REPLACE THE SEPERATOR PLATE IS MORE THAN SLIGHTLY OVERCHARGING YOU, ALSO THE PLASTIC PLATE HASNT BEEN USED SINCE 2001, SO YOU ARE BENT OUT OF SHAPE ABOUT AN OIL LEAK ON A 13 YEAR OLD CAR AND THE NEWEST.

        Best of luck

        Justin

        • Paul Blohm May 3, 2013 at 9:43 pm #

          lololol ouch JOE CLIENT, it looks like that third degree burn hurts. Anyways, I just wanted to thank you Justin for the amazing video. I’ve got my EJ22 on the stand right now waiting for some new Head Gaskets. Looking behind the Flywheel there is a ton of caked on oil. It’s nice to be able to order the part before I tear it down and have the failed part in my hand, wondering what it’s called. ;P

  4. Candice June 11, 2010 at 9:04 pm #

    Any suggestions as to what may be causing oil loss in a 1999 Forester (Canadian)? Runs great, no other problems,only 94000 km…..but oil seems to disappear without a trace. Nothing apparent in coolant overflow, engine very clean, no drips, no smoking….but have to constantly check and refill. Thanks for any help and for the great site!

  5. Justin Stobb June 11, 2010 at 11:03 pm #

    Candice,

    There are many possibilities, from a pcv system issue, to a mechanical engine deficiency with the valve stem seals, guides or piston oil rings there is just no way to know with out some investigating. How long are you going in between oil changes and have you been able to figure out at what point AFTER an oil change it starts to use oil.

    Justin

  6. Candice June 13, 2010 at 10:51 pm #

    Thanks for your speedy reply, Justin – haven’t been able to get to my mail for a couple of days. The original owner of my Forester had regular dealer service for the first 60000 km (oil changes per 6000 km) and I’ve done oil and filter on the same schedule for the 10000 km I’ve had it….(not sure about the 20000 km in between). I’m not sure what was in in it when I got it, but I’ve tried both 10W30 and the recommended 5W30. Does seem to make a difference. The oil loss might be slightly less of an issue for a couple of tanks of gas worth of driving right after the change. (But, again, never any performance issues, smoking, etc.)

  7. Candice June 13, 2010 at 10:53 pm #

    oops, that should have said (oil weight) doesn’t seem to make a difference……

  8. Justin Stobb June 14, 2010 at 6:44 pm #

    Hi Candice,

    I would start by using Castrol 5w30 synthetic blend, if that’s not what you are already using, as we have truly had a few cars consume less oil after making the switch.

    Other than that, it would be good to have someone look at the long term fuel trim data on a Subaru select monitor or the equivalent.

    If after both of the above are addressed and either it doesn’t help or there is no problem found in the possibility of dilution of the engine oil than you really are only left with some sort of a mechanical engine issue causing the problem such as piston oil rings and or valve guides, seals.

    Hope that helps

    Justin

  9. Candice June 14, 2010 at 7:18 pm #

    Thank you very much for your help. I’ll try the oil, and look into the PCV issue for starters….and will post again if I manage to solve the mystery. Thanks again for the great resource!

  10. Mark Johnson October 25, 2010 at 11:10 pm #

    A friend of mine had a new engine (from Japan I think) and a new (possibly ebuilt transmission?) installed which came from Texas in installed in his 2000 Outback. Now it drives goofy so much that the mechanic that worked on it had to unhook the front axles so it is now only rear wheel drive. They have been unable to figure out what is wrong. Any ideas?

  11. Justin Stobb October 27, 2010 at 3:15 am #

    HI Mark,

    The transmission that was put in has the wrong Gear ratio.

    Wish your Friend The best of luck, he is going to need it.

    Justin

  12. GreasySmurf December 3, 2011 at 7:14 pm #

    Excellent video, thank you for putting it together. I have that exact engine, so this is very relevant.

    I’ve been fighting with a back-of-the-engine oil leak since completely rebuilding my engine (following an overheat and shattered rod bearing due to running w/o oil).

    It does that Subaru thing, where oil is pouring out of the back of the engine, burning off the cat and inspiring concerned citizens to roll their window down and tell me my car is on fire. Embarrassing.

    Have tried the following so far in my attempt to fix it:

    1) Removed engine, replaced rear main seal. No help.

    2) Doubting the quality of my main seal install, removed engine again, did more careful main seal install. No help.

    3) Did my internet research, learned of separator plate issues, and replaced oil separator plate. First, pulled the engine forward w/o removing it, didn’t see the level of evidence of leakage like the video shows, but that’s probably due to the recent rebuild, clean oil, etc. Notably, the main seal seemed dry, a trickle around wrist access panel just like the video, and some leakage under separator plate. Before removing the old plastic plate, I confirmed at least a small leak by forcing compressed air into the PVC tube shown in video, and rotating the engine via the front of the crankshaft using a drill. On removal the old plate showed only the beginnings of cracking near the screws, leaking was apparently due to a void in the Ultra Copper sealant I had used during the rebuild. Installed the new stamped steel plate & new fasteners, using Permetex Ultra Grey bead for seal. No help.

    4) Lifted engine to remove oil pan, cleaned and reinstalled using aftermarket cork gasket. Used thin layer of Ultra Black on pan side and torqued to spec. Thought was, maybe primary leak is from back of oil pan seal. No help.

    5) Present day. Engine’s still in car, still leaking like crazy. I left off the cover panel under the bellhousing, so I can peer up into the main seal area using a small dental mirror from below the car while illuminating with a headlight through an access hole I found at the top of the engine – and I can see the separator plate is still leaking when the car is running. Should I assume the problem is with my choice of sealant? Exactly what sealant should I use? Anaerobic maybe? What about creating a gasket, (that seems like a good idea to me)?

    Thank you. As good as I’m getting at pulling off my engine, I think I’m also becoming insane. Your advice is appreciated! 🙂

    • Justin Stobb December 5, 2011 at 10:23 pm #

      If you installed the rear main seal in to far it will leak as the block is stepped. It could be the sealer try Subaru 3 bond, it could be the breather hose above the sep plate?

  13. Jeffrey July 24, 2013 at 7:01 pm #

    I have my ’01 going in for a clutch change next week. I have a new rear main seal, and will get a new o-ring for the wrist pin cover. (may not be able to get the actual Subaru part in time, but I looked it up and from what I can see its a 31mm x 2.0 mm o-ring which I should be able to source.

    The oil separator plate should be aluminum based on the fact that its a 2001 model, and if it were plastic I would likely have a huge mess oil at the rear of the motor, and I don’t.

    Do we reseal the existing aluminum plate?

    Or should I get a new stamped steel one?

    I understand that the screws can be difficult to remove, requiring an impact driver. Gotta be a lot easier then getting rusted out brake rotor bolts on a Honda or Hyundai though….

    I’ve got 310,000 km on the vehicle, and this is the first clutch replacement. One head gasket has a minor oil leak, I would say not even half a teaspoon between oil changes. Minor amount of oil on bottom of engine, but it does get onto the exhaust and smells bad, more so in the rain when the oil is washed deep into the heat shields.

    I figured that I would leave the head gaskets as is until I have a serious leak, and only deal with whatever I can get to during other repairs, such as the seals behind the flywheel next week.

    Thanks!

  14. Misha May 10, 2014 at 9:12 pm #

    Just curious a 98 subaru legacy automatic has had a complete engine rebuild the rear main seal was replaced perfectly and the cam shaft seals have been replaced three times the cam shaft seals and the wrist pin access plug are both leaking oil still I have replaced the o ring in the access cover twice as well what can be causing this the separator plate is clean it has me stumped

    • Justin Stobb May 12, 2014 at 9:09 pm #

      Hello Misha,

      Sorry to hear you are having all that trouble. Sounds like there is no diagnoses of what area is leaking, cam seals are in the front and thew Seperator is in the back.

      Find someone who knows Subaru and they should be able to help you locally, With out a clearer idea of where the leak is coming from I cant make any real suggestions.

      -Justin

  15. Donald May 21, 2014 at 11:43 pm #

    I have a 2002 Subaru Forester L. Based on previous comments, it is likely to have an aluminum oil separator cover – am I correct? If so, the aluminum is better than the plastic, no?

    • Justin Stobb May 22, 2014 at 5:43 pm #

      Hello Donald,

      The 2002 would have come with an aluminum Seperator plate.

      -Justin

      • Donald July 11, 2014 at 4:57 am #

        Ah great. Thank you.

  16. David Anderson July 29, 2015 at 9:26 am #

    Hi Jason, When you say: “… it could be the breather hose above the sep plate?” What do you mean? Does the hose have a hole or a bend in it? An obstruction? Help?

    Also, could the rear main seal being pushed in too far upon installation cause the seal to leak or would it cause the sep plate to leak?

    The original cone shaped screws, if the least bit overtightened, act as wedges to split the plastic, now made brittle by thousands of hot/cold cycles.

    Much thanks, friend, as I look at my third try to stop this leak.

    • Justin Stobb July 29, 2015 at 11:53 am #

      There is no Jason here..

      There is a PCV breather hose above the Sep plate, the Sep plate separates oil liquid from oil vapor, the vapor travels up the breather hose to the PCV. The hose can become brittle and crack, the clamp can fail, it could fail in the same way any other rubber hose can fail.

      If the rear main seal is installed to far it will spin and yes leak as the block is stepped. there is a tool that sets the seal into place at the proper location at the end of the Chamfer in the block.

      Justin

  17. Maia October 9, 2015 at 12:28 pm #

    Hi there,

    What’s the urgency on a pretty substantial separator plate leak? What kind of damage does it cause, and how long is too long to wait?

    • Justin Stobb October 13, 2015 at 9:56 am #

      Hello Maia,

      Its always difficult to comment on with out seeing it. But if its an automatic car the oil leaking out typically poses damage to the environment only as long as you keep up on the oil, now it can get to the point where the exhaust is so coated in oil it catches fire. On a manual trans car the clutch can become oil soaked and slip.

      -Justin

  18. Amy B March 3, 2017 at 9:51 am #

    My cousin just pulled my engine and replaced all of the gaskets to try stopping the awful leak. Turns out this is where a major issue is, as it’s still leaking terribly. Will he have to pull the whole thing again to replace this??

    • Justin Stobb March 8, 2017 at 1:03 pm #

      Hi Amy,

      You must either pull the Engine or the Transmission to make this reapir.

      -Justin

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