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Breather box question 200 1986

Stakerjack posted an earlier question about an oil leak. I have the same problem. Even after replacing my flame trap and making sure all the related hoses were clean and clear, I don't recall knowing what the breather box is for. Everytime I've heard this mentioned, I thought it was related to the air filter box being the breather box. What and where is it?

Thanks in advance.








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    Breather box question 200 1986

    Maybe I should be getting myself a new breather box before replacing my seals/gaskets!

    --
    '86 245, 283,000 mi., '87 760T engine compartment burned to a crisp








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    Breather box question 200 1986

    Hello:

    The oil separator box is located on the block just below your flame trap housing-- they are connected by a short rubber tube. This box is black plastic and contains baffles that allow the oil fumes to condense and run back down into the pan or to be carried up to the air intake to be burned if they are in airborne form.

    The simple blow-through test is a very crude measure of the breathing ability of the box. I have had cars with oil leaks that "passed" this test. Basically, if your flame trap and the associated upper plumbing are clear, then the most likely cause of your oil leaks is partial blockage causing elevated crankcase pressures, with the oil following the path of least resistance and leaking from seals or the filler cap.

    You can remove the box without pulling the intake manifold-- remove the IAC valve and its hoses for more access, and use extensions and a universal between the intake runners to get to the 12mm bolts. You will need an 0-ring that seals the box to crankcase. The wiring harness in the vicinity may be held to the top of the box with a small bolt as well (8 or 10mm).

    Once you have it off, use screwdrivers and picks to scrape out as much crud as you can. Then tap it vigorously and shake to loosen more debris. Once you get the big stuff out, soak it with carb cleaner, block the ports and shake it. I ran hot water through mine and tapped the sides at the same time, which resulted in much more debris coming out.

    My 200K mi+ 945 "passed" the blow-through test, but was leaking a small amount from the rear main and front seals. I cleaned the oil separator and put things back together-- no more drips in the driveway. Your results may vary, but it is worth a couple hours in my mind.

    Some here have advocated simply replacing the oil separator box-- that is an option you could consider too. Cleaning it takes patience, and because of the baffling inside, you never really know how clean you have gotten it.

    Good luck!

    --
    Herb Goltz, Aurora, Ontario, Canada '92 245 w/130K mi, '92 945T w/200K mi








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      I agree 200 1986


      I agree - the blow-through test does not fully confirm the breather box is clear.
      This is because the breather box needs and has TWO openings down into the crankcase. If one is blocked then air will blow through when testing, but the breather won't function properly with one passage blocked.

      I used the method Herb described to get my breather box out. I found it in the FAQ. It's under "Engine: Seals, Belts, Crankcase Ventilation". You follow that path down to cleaning the crankcase ventilation / Flame Trap system. There are writeups on several methods of getting the breather box out.

      If you do this you may as well clean the idle air control at the same time - since you will remove it. I also cleaned the throttle body and checked + cleaned the accordion hose to the TB. Get a TB-to-intake manifold gasket; you might need one. I didn't. Seems to work fine without any gasket sealant added. These parts clean up nicely with carburetor cleaner.

      With the breather box off, I also carefully cleaned the tube leading down into the forward opening to the crankcase (rear opening has no tube). As posted elsewhere here, if you break the fragile tube you will be very sorry. So be careful if you do this.

      I trickled in some GUNK engine cleaner (NAPA brand is also available). The stuff that is meant to clean the internal oil passages and oil pan insides. It loosens up any gunk in the tube. This requires an oil change afterwards. I then probed carefully with a single split of household extension cord (no metal sticking out), and then with a fairly stiff synthetic rope. This cleared the tube's innards.

      Good luck!
      --
      Sven: '89 245, IPD sways, electric rad. fan conversion, 28+ mpg - auto tranny. 850 mi/week commute. '89 245 #2 (wifemobile). '90 244 (spare, runs).








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    Breather box question 200 1986

    If you follow the hose below the flame trap down it will attach to the breather box, it's about the size of a big man's fist and it's kind of buried under the fuel injectors and the intake manifold.

    as stated by mgarageu it has 2 bolts that bolt it to the engine block...

    I imagine it's possible to remove it without first pulling back the intake manifold but it sure is easier to get to if you have the manifold off and or separated from the engine (if you do this remember to have an intake manifold gasket ready to apply upon reassembly).

    you can check the breather box for being clogged by this action
    1. remove the flame trap...
    2. attach some kind of longer hose to the top of the breather box (or use the hose that had the flame trap in it if you can reach it)...
    3. remove the oil filler cap
    4. try to blow through the longer hose you just installed... if it is hard to blow through than something is clogged in there, if it is pretty easy to blow through than it should be ok.

    jack
    --
    '86 245, 283,000 mi., '87 760T engine compartment burned to a crisp








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    Breather box question 200 1986

    small black item bolted to the engine block near starter and oil dipstick tube. it separates oil from crankcase gases. if dirty - symptoms the same as flametrap dirty...the hose from flametrap just goes on it...
    --
    i prefer non-german cars







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