Saturday, 28 November 2015

BMW E90 320i N46B20 Valve Cover Membrane / Diaphragm

DIY Disclaimer: I hold no responsibility should anything goes wrong when you decided to follow my guide. It’s strictly meant as a reference for knowledge sharing purposes.

Symptom:

We can smell oil fume from inside the cabin through the a/c vents but it stops when we switch to internal air circulation mode.

From the engine, you will notice the valve cover is wet with oil stain as follows

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A check on the parts catalogue revealed that this N46 engine belongs the the LCI model with 156hp, some called it N46N as my E90 320i was the last batch of the pre-LCI model. There is no more CCV in my model

Below is the part catalogue for my vehicle where this membrane is missing:

Part Code: 11127555212

http://bmwfans.info/parts-catalog/E90/Malaysia/320i-N46N/R-N/browse/engine/cylinder_head_cover#7555212_1

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Online search pointed me to this website where they actually make the repair kit: http://vanos-bmw.com/membrane-for-cover-n46n-bmw-11127555212

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I then contacted the local parts dealers and found out they do not sell the repair kit, but the entire valve cover.

Running out of option, I attempted to pry it off and see where it takes me..

After one hour of careful prying.. VIOLA!!

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You will notice centre of the membrane has detached from the rest of the section, hence allowing oil fume to escape.

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Carefully, I cleaned them up, took out my cobbler glue and used bicycle tube (refer to the black color item below, shaped like a flower Open-mouthed smile).

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Then I put them together.. to reinforce the broken centre piece.

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Mission accomplished!

I assemble the kit and cap it back in. One mistake, I forgot to reattach the spring.. Smile with tongue out

Another round of prying to refit the spring.

Thank you for reading and please provide feedback or query if any.. Winking smile

Updated: 11/4/2016..

It has been working fine now. 6 months down the road..

Ta-dah! No more oil stains, only dust stain. The leak was actually very serious, I lose lots of engine oil.. so mush so, it drips on my porch. Now my porch is dry like a dessert.. ! I’m pretty sure if I were to visit a mechanic then, they will most likely advise to replace flywheel oil seal and oil pan gasket. Pheew!

To all N46N owner out there, please take note!

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21 comments:

  1. This comment has been removed by the author.

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  2. Will the N46N vavle cover fit on my N46 pre face. Since i can only find that cover at my local scrapyard for a good price

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    1. I have no idea if they are competible. Why do u need to change the cover? My valve cover due change because my essentric valve connector the nut was loosed, yet I epoxy it back. Unless your cover is cracked..

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  3. Hello Astroboy,

    First I would like to congratulate you for the blog. I have a 2009 320i LCI with the same engine, so your experience is always helpful.

    I was having some oil leaks on my engine and decided to investigate the possible reasons. One possibility was that the Positive Crankcase Ventilation (PCV) valve was stuck closed, so this would increase the pressure inside the cylinder head cover and lead to leaks.

    This link shows how the PCV system works on the N46, and similar BMW engines: http://www.bimmerfest.com/forums/showthread.php?t=911135

    Since you had an oil leak after the oil separator on the cylinder head cover, I think that maybe your PCV valve was stuck open.

    The problem with the fix that you did is that your valve could not be working properly now and this could lead to future problems.

    Another thing is that the cap on my engine is different than it is in yours, as you can see on this picture: http://i.ebayimg.com/images/g/pY4AAOSw0QFXB4Qi/s-l1600.jpg. Maybe this design update to avoid this kind of problem.

    My suggestion is buy a new cap with the new design and a new valve to avoid any future complication. Well, this is my 2 cents.

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  4. Thanks for your comments. Problem was there is no part number for the PCV. It is not meant to be a replaceable component. It only comes with the entire rocker cover which I believe is overkill.

    And to add on, the link you provided is for the N52 engine with a blow-by-gas inlet, ours do not have this. What my fix did was just to mend the torn diaphragm. It did not alter the characteristic of the PCV. I might be wrong and you are welcome to correct me.

    Thanks.

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    1. Thanks for the reply.

      Yes, as you pointed out if you want to use an original BMW part you have to buy a new valve cover, but there are aftermarket valve only options.

      The link shows a different BMW engine, but I believe that it works the same as ours, like any PCV system. Other BMW engines have a PCV system called CCV, that does the same thing.

      If you look at picture #6 of your post, the blow-by-gas outlet is on the center of the circle and the blow-by-gas inlet is the other hole.

      thanks.

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    2. I am unable to source for after market option, if you have the contact, please share with me.

      Our car do not have CCV, CCV only for the non-membrane version which crank vent hose connected to oil separator, which then has a return hose to oil sump.

      Ours is just a membrane to regulate crankcase pressure. Our crank vent hose connects directly to the intake manifold, just like Japanese cars. There's only one hole under the membrane, it doesn't breath.

      I suspect our intake manifold is now flooded with engine oil..

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  5. I was able to find the valve on ebay, bellow are the links:

    http://www.ebay.com/itm/Repair-kit-N46N-N46K-N46T-BMW-11127555212-/112012270870?hash=item1a14739d16:g:AXQAAOSw7KJXD8im&vxp=mtr

    http://www.ebay.com/itm/New-Cylinder-Head-Valve-Cover-for-BMW-E60-E85-E88-E90-E91-E92-E93-All-N46-Engine-/111962168150?hash=item1a11771b56:g:p7YAAOSw8RJXB4Qf&vxp=mtr

    Yes, our car doesn't have CCV. I think CCV is for cold weather markets, because it has an electric heating system.

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  6. Oh! That's what I shared in my blog too i.e. www.vanos-bmw.com

    But my cheap fix does exactly the same, which is to mend the torn membrane at a small fraction of the price.

    The CCV oil separator is not a market dependent add-on but is for all the pre-LCI model with 150hp N46 including the E46 318i. My e90 320 is late 2007 pre-LCI model with the LCI engine called 156hp N46N engine.

    The there's no electric heating.. http://bmwfans.info/parts-catalog/E90/Malaysia/320i-N46/R-N/jul2007/browse/engine/crankcase_ventilation_oil_separator/

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  7. Yes, probably was an engine design update on the LCI.

    The #4 picture of your post shows the version of the engine that doesn't have the PCV valve cap (over the top) because on that version the PCV system is outsite the engine (as you showed on the link) and not over the valve cover.

    BMW calls CCV their PCV system. In our engine model the PCV is on the valve cover, so it has the PCV valve over the cover.

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  8. hey, astroboy, my 320i also a N46N engine, (last batch of pre LCI), and i found some hot gasses come out from this bloody cap, but have no oil leak(regulator on valve cover).

    is that normal that got some pressure inside the cylinder head cover?

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    Replies
    1. The diaphragm is air tight. If hot gasses can escape means torn diaphragm.

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    2. The diaphragm is air tight. If hot gasses can escape means torn diaphragm.

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  9. Funny thing my e90 lci n46n engine membrane was torn but wasn't making any noises, in my country we can get a hold of it easily on mercadolivre because we make it here https://veiculos.mercadolivre.com.br/acessorios/diafragma-suspiro-bmw-320 so i bought one and replaced it and now it keeps escaping gases from the top and making annoying noises with no aparent reason

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    Replies
    1. Nice to hear that you can get the replacement membrane.. as for the noise, it shouldn't happen.. did you forget to install the spring?

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    2. Found out that i forgot to install the black plastic piece that come inside the original membrane.

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    3. I forgot the spring and had to take out again.. which was a pain.. LOL! 😅

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  10. This comment has been removed by a blog administrator.

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  12. Hi astroboy, thank you for writing this blog post. Finally found someone with the similar issue.

    My membrane in PCV vent valve is teared up, so it caused rough idling and whistling noise. You can feel the vacuum when you placed your hand on it during engine running.

    My indi workshop made same modification to PCV vent valve by installing double rubber layer to prevent the vacuum. It works and it stop the rough idle and whisting noise.

    However, my oil consumption went up as high as 1 ltr/ 600 km and sometimes a white smoke come from the exhaust when I step on the accelerator. The white smoke is not visible during idle.

    Do you think its because the membrane is being blocked by the rubber layer so the oil is consumed by the engine?

    Currently waiting for the PCV vent valve repair kit from ebay which take forever to arrive.

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