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Subject: engine noise, whine, howling, oil separator valve Author: cmartin248 : member since January, 2005 : 5 posts Posted on: 2005-01-20 14:43:44

Let me begin by saying I have really enjoyed and learned a lot from this board. The following symptoms began on my 740 at about 100k; very rough idle sometimes, missing badly at low speeds, and last the engine began to whine or howl. After replacing the A/C belt idler assembly ($80), I began to look at the alternator for the whine. This noisy was very hard to pin point even with a stethoscope. After reading the board I saw the articles on the “oil separator valve” (same as an EGR valve on other cars). The test for a failed valve was simply remove the dipstick and see if air sucks in, or the engine changes pitch. With the engine idling, I removed the dipstick and the air rushing in, not only changed the pitch of the engine, but it died.

Here is how I changed my valve and keep in mind I have done some mechanic work all my life. I will try to make this as painless as possible and simple enough for anyone who knows the right end of a hammer to DIY (do it yourself). See, I even explained that one.

You can order the valve online for about $76 or go pay the dealer $96. I didn’t bother replacing the o-ring gasket and don’t see any reason to, unless you damage it.

Start by having the engine cold. I will give all directions as if you are sitting in the driver’s seat. On the back of the engine intake, you will find a black plastic plate, about ½ inch thick and 5” X 7”. This is the evil demon of very poor design. You don’t have to remove the intake. I will repeat “you don’t have to remove the intake”. You will need a couple of tools that some people may not have. You need a small ¼” pull-handle (not ratchet, too big headed) and a ¼” X 30 torx bit.

Before you begin removing bolts, remove the right hand end of the heater hose that is attached behind the valve plate, on the right hand side. Check it for damage and it’s a really good time to replace it. Remove the two small vacuum lines at the top of the valve plate. They simply pull off. There is another vacuum hose attached to the back of the plate with one of those permanent crimp clamps on it. I hate those things and I simply used a pair of pliers to twist it off.

Now the tricky one, there is a metal tube with a snap-on clamp on the bottom left hand corner, but on the front side of the plate. This one is easy with a long thin screwdriver, just pry it off and be gentle (you will re-use this one).

Now start removing the #30 torx bolts. There are seven of them and sort of tight to get to, but I think you can handle it with those tools. Once all of the screws are removed, just pry the plate off. It shouldn’t be struck very hard, but even if you damage it, you’re going to replace it, SO GET THE BIG HAMMER! Just kidding.

When you are installing the new valve, be sure and apply a light coat of grease to the rubber o-ring on the metal tube connection as well as the one in the center. I put a little silicone around the sealing surface of the plate, but you probably don’t have to. Don’t force the plate back on with the bolts, if you get the connections to slide into the tubes, it will mate up just fine. Total time is about 1 hour.

I have some pictures of the valve, the failure, and tools, but I don't know how to post them (will email). BMW could have easily designed this to allow the owner to replace this diaphragm by snapping the back cap off and replacing the rubber for a couple of bucks,, but NOOOOOOOOOOOO! This poor design is exceeded only the radiator engineer. (probably the same person).

• engine noise, whine, howling, oil separator valve (pic) - cmartin248 2005-01-20 14:43:44 (39704 views)
  • Re: engine noise, whine, howling, oil separator valve - Sam Carleton 2005-12-21 10:43:41 (3267 views)
  • Additional notes and caveats on OSV procedure - davidsoine 2005-11-26 19:50:03 (3568 views)
    • more on the tube running through the intake... - davidsoine 2005-11-27 00:06:05 (2955 views)
  • Here are additional photos (pic) - cmartin248 2005-01-21 23:59:39 (7131 views)
  • Could you post pic of this 'in place'? - 747 2005-01-20 23:32:21 (3068 views)
  • Nice post - Thanks. (nt) - WTH 2005-01-20 23:14:10 (1740 views)
  • Thanks, and do you have a picture of the tools? (nt) - silber98 2005-01-20 22:31:17 (1975 views)
  • Very nice write-up, thank you! But I don't know... - pdef1949 2005-01-20 16:08:32 (2394 views)
  • Very good work! (nt) - DavidC 2005-01-20 15:19:12 (1751 views)
  • Re: engine noise, whine, howling, oil seperator valve - ccuevas 2005-01-20 15:16:21 (3509 views)