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N52B25 high oil consumption
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06-27-2019, 05:27 PM | #1 |
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N52B25 high oil consumption
Hello guys!
My 2005 E90 325i is consuming 1l of oil every 500km. There is no observable blue smoke and no significant leaks were detected. Huge blue smoke on first startup of the day after revving a bit and oily intake led us to the conclusion that PCV system was bad, and we changed it. The blue smoke on startup disappeared, but sadly the oil consumption remained. There are no engine error codes with INPA. What could be causing this and how could I troubleshoot the issue? Thanks, nbK |
06-27-2019, 05:55 PM | #2 | |
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Do you smoke on de-acceleration ? |
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06-28-2019, 02:36 AM | #3 |
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06-28-2019, 05:13 AM | #4 |
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high oil consumption is problem of the n52b25 by design
n52b30 do not have this problem this problem was resolved by BMW in 2010 by changing cylinder rings design and since bmw shipped n52b30 in e9x 325 cars in us, the people from US do not know this problem
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06-28-2019, 07:41 AM | #5 | |
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Edit: I also checked compression and it was 13.5-14 bar around all 6 cylinders so piston rings should be ok. Last edited by n00b0rKa; 06-28-2019 at 09:02 AM.. |
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06-28-2019, 01:49 PM | #6 | |
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Maybe it helps, I attached some photos of my spark plugs before the PCV replacement. The deposits were uneven, the middle ones were the most affected. |
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06-28-2019, 02:22 PM | #7 | |
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06-28-2019, 05:16 PM | #8 | |
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06-29-2019, 01:17 AM | #9 |
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06-29-2019, 04:46 AM | #10 | |
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if you cut it out , you'll see smoke also you a doing compression tests on cold motor, the running motor have another temp and pressure conditions generally oil consumption goes high due following problems 1. congested or not working PCV system, you have to replace external PCV valve on motors with grey cover or whole engine cover on motors with black cover(PCV valve integrated) 2. worn valve seal rings(rubber covers on valves, loose its flexibility under high tempeature) 3. piston rings (n52b25 design flaw, part number changed by BMW in 2010) and 325 cars with n52 after 2010 do not have this problem
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06-30-2019, 04:45 PM | #12 |
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Just past 170k km, verified at dealership, last registered info last year in 160k.
I will do another 500km trip in the following days, I will keep you updated about how my oil consumption goes after two bottles of oil treatment. |
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07-01-2019, 06:14 PM | #13 |
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Update: 500km and 1 water pump failure later, still consumes 1l of oil every 500km. When standing still and revving the engine, a light puff of blue smoke appears just as I let go of the throttle. On deceleration, nothing significant can be seen, and some blackish smoke can be observed when accelerating on full throttle.
Does it still resemble the signs of bad valve stem seals? Shall I also change the piston rings as preventive maintenance if I take the cylinder head off? Thank you so much for your help guys! |
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07-02-2019, 01:32 AM | #14 |
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The piston ring issue is apparently that the oil control ring gets clogged with carbon. So piston rings can be your problem, though compression is still good.
Valve stem seals are the other common failure on these engines, so hopefully it's them and not the rings! If it is the rings though, you can just keep topping up. 1l/500km is quite a lot though! Did it suddenly start using that much oil, or has it been a gradual increase? |
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07-02-2019, 11:29 AM | #15 | |
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Today I took out my larger DISA and the whole intake is covered in a coat of oil, and the PCV was just replaced 1 week earlier. I think this rules out somewhat the possibility of valve stem seals, the issue being possibly either a valve cover gasket or the piston rings. Here are some photos, please let me know what do you guys think. Thanks a lot! |
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07-02-2019, 11:13 PM | #16 |
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It's perfectly normal to have oil in the intake. Im a mechanic by trade and have had a lot of these engines apart. They all have oil in the manifolds. The PCV breather hoses go into to the manifold, that is where the oil comes from. When i removed my DISA valve to rebuild it, it was FULL of oil. My engine doesn't use oil so i wouldn't be concerned about it.
Are you sure the lower PCV hose that goes into the sump is not blocked? If you still have that bore scope, i would pull the spark plugs and check the bores for any score marks Last edited by N52bigblock; 07-02-2019 at 11:19 PM.. |
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07-03-2019, 04:30 PM | #17 | |
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Last edited by n00b0rKa; 07-03-2019 at 04:39 PM.. |
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07-04-2019, 03:19 AM | #19 | |
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How sure would you be that I don't replace my valve stem seals in vain, something else being the problem? Would you also replace piston rings if the head comes off, as those are also known to be a common problem? Thank you so much for your help guys, nbK |
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07-04-2019, 08:02 PM | #20 | |
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You don't have to remove the head to do valve seals. If you were rebuilding the engine and doing rings and bearings, then doing valve seals is also part of doing a rebuild, so if you did the valve seals first and it's not that, then you haven't lost much really. Is there much carbon build up inside the valve cover, on the camshafts etc? Could you post a picture of it possibly? |
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07-05-2019, 09:08 AM | #21 | |
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I took some shots and attached them below. I don't think there's excessive carbon buildup. When I got the car, before the first oil change I had 1l of ATF ran through the engine while idling for good 15 minutes, because I had that classic N52 lifter tick, but the ATF solved that. Didn't have the time to take the spark plugs out yet. Do you think it's worth the hassle to bloc the PCV to show if there is unhealthy amount of blow-by? Regarding the seals without head removal, I've seen a method with compressed air, however it looks risky, the valves can easily fall into the engine... I've also seen a special tool with magnet on it (?) to prevent the valves falling in. Do you know some other method? Also someone told me I can mess up my VANOS doing valve stem seals, but I don't really see how. Thank you so much for your time, nbK |
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07-05-2019, 02:20 PM | #22 | |
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There is absolutely no risk of the valves falling into the engine if you have the piston on TDC for each cylinder you are doing the seals on. So when you are doing, lets say, cyl 3 you turn the engine over the piston is at the top of it's travel, then do the seals. You would then do cyl 4 as that is also at the top of it's travel at the same time as cyl 3. That's how i do it, as well as using compresed air, so even if the compressed air fails, it is still impossible for the valve to drop into the engine. As for the VANOS.That guy is talking total bullshit and has no idea what he's on about. There's a lot of people out there who think they "know about cars" and spread ridiculous bullshit rumours. I find that really annoying. They think they know everything but actually know sweet FA. Last edited by N52bigblock; 07-05-2019 at 02:30 PM.. |
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325i, consumption, n52b25, oil |
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