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Thread: Excessive crank case pressure

  1. #1
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    Excessive crank case pressure

    So I wanted to make a thread about this really quickly to try to summarize the things I've read throughout numerous threads on this forum on how people are setting up their PCV systems. Hopefully I'm not cluttering up this forum with another PCV thread but I'd like to make sure I'm thinking about things correctly.

    I recently bought a turbo m3 with an s52 converted to OBD1. I'm getting oil slightly seeping out of the oil filter cap after a few pulls, as well as strong oil smell. This motor was said to be rebuilt just recently but I will be testing compression on the motor as a possible cause for excessive crankcase pressure.

    My PCV system is set up as follows:
    valve cover to Burger catch can replica (looks to have the same type of baffling). This unit is not vented to the atmosphere.
    Catch can to intake pre turbo.
    My dipstick drain has a breather filter on it (yeah)
    The hoses are a large diameter and don't seem to be restrictive, although the catch can to intake hose is rather long.

    I can't see why this set up could be causing issues, it's not restrictive in any way other than possibly the long hose from the catch can to the turbo inlet. any thoughts on this? I assume everyone elses who uses this set up to pull vacuum has a hose around the same length as mine so I don't see why this should be an issue.

    Another thought, and excuse me if this doesn't make sense, I haven't really fully wrapped my head around the concepts involved with this subject; Could having my dipstick drain open to the atmosphere be causing an issue with my PCV system? I also understand this could be the reason I can smell oil so strongly.

    Looking forward to hearing your guy's thoughts. Thanks

  2. #2
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    I would do a compression test on it


    86 325es, 2.8L m50, S476sxe, ProEFI 128 ecu, e85, solid rear axle, TH400 trans, 28x10.5w slicks, zip ties, popsicle sticks, tape
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  3. #3
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    I'm having a similar issue. I have a fresh motor and during a tuning session last month I am getting oil coming out of my oil pan gasket, turbo drain pushing oil up into the turbine and at one point oil started coming out of the oil filter housing. Also the pistons are covered in oil.

    I did have the "Y" vent on my dip stick plugged though.

    I am now trying something I read on here that involve the secondary air pump from a Furd or Toyota, a catch can, and tapping some vents in the valve cover. No joke, these things sitting in boxes at the house. I will go for tuning again in a month or two. I'll post how it goes.

    https://www.ebay.com/itm/Universal-C...53.m2749.l2649

    https://www.ebay.com/itm/Secondary-A...53.m2749.l2649

    https://www.ebay.com/itm/SPAL-FRH-Fa...53.m2749.l2649
    TEC-3R, T4 GT40, WISECO, EAGLE, SUPERTECH, O-RING'D "FRANKENSTEIN" STROKER.

  4. #4
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    Quote Originally Posted by someguy2800 View Post
    I would do a compression test on it
    Seconded. Someguy2800 and I tore my motor apart and found the cause of my excessive crankcase pressure to be broken ring lands. I've got 2 -10AN lines off the valve cover going to a vented catch can, and I only get condensation out of it now.

    Sent from my Nexus 6P using Tapatalk
    '95 E34 525i, M50B32 (S52 Crank, K1 Rods, JE 9.0:1 Pistons, S52 Cams, Cutring, Achilles Oil Pump Shaft & Sprocket), GTW3684R 0.82A/R, ZF320

  5. #5
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    Do you remember what your compression numbers were?
    TEC-3R, T4 GT40, WISECO, EAGLE, SUPERTECH, O-RING'D "FRANKENSTEIN" STROKER.

  6. #6
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    Quote Originally Posted by trthrrt489 View Post
    Do you remember what your compression numbers were?
    My compression numbers - leakdown results were as follows:

    1: 120 - 33%
    2: 90 - 30%
    3: 185 - 18%
    4: 185 - 18%
    5: 50 - 60%
    6: 110 - 45%

    Keep in mind that different gauges may read differently. 4 out of the 6 cylinders had busted ring lands.

  7. #7
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    Quote Originally Posted by CallMePuff View Post
    My compression numbers - leakdown results were as follows:

    1: 120 - 33%
    2: 90 - 30%
    3: 185 - 18%
    4: 185 - 18%
    5: 50 - 60%
    6: 110 - 45%

    Keep in mind that different gauges may read differently. 4 out of the 6 cylinders had busted ring lands.
    Very cool. Thank you. Didn't mean to hijack the OP's thread.
    TEC-3R, T4 GT40, WISECO, EAGLE, SUPERTECH, O-RING'D "FRANKENSTEIN" STROKER.

  8. #8
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    For reference, this is my catch can set up and it works just fine. I know Someguy2800 literally just has a hose off the stock valve cover vent port with a breather filter, and he pushes many more horsies than I do.

    Sent from my Nexus 6P using Tapatalk
    '95 E34 525i, M50B32 (S52 Crank, K1 Rods, JE 9.0:1 Pistons, S52 Cams, Cutring, Achilles Oil Pump Shaft & Sprocket), GTW3684R 0.82A/R, ZF320

  9. #9
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    I also vent valve cover to atmosphere and dipstick return to atmosphere.. Was never sure about the dipstick tube though I would also like to know about that part.. I dont think many people are using pre turbo to pull vacuum

  10. #10
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    Hmmm, I’ve been getting a lot of oil out of my turbo and into my Intercooler piping and Intercooler. Too much for my liking. I only run a breather filter and hose coming from the crankcase. Any things to check out.

    I was told perhaps the way the turbo is clocked could cause these issues, it seems excessive and I want to nip this in the bud.

  11. #11
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    Quote Originally Posted by Darth Maul View Post
    Hmmm, I’ve been getting a lot of oil out of my turbo and into my Intercooler piping and Intercooler. Too much for my liking. I only run a breather filter and hose coming from the crankcase. Any things to check out.

    I was told perhaps the way the turbo is clocked could cause these issues, it seems excessive and I want to nip this in the bud.
    That sounds like it's probably unrelated to crankcase pressure, but you could rule it out with a compression test. I would think a breather filter on the crankcase would be fine. Is it the stock hose diameter? I would also assume that if it were
    too much positive pressure, it'd be pushing out of your seals.

    Is your oil drain straight down, no kinks? Is it put into the top of the oil pan or higher? Does your turbo require a restrictor in the feed? Is your compressor housing tightened down well? I'm not sure how else it'd be getting past the seals on the turbo.

  12. #12
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    Every time I have this issue I replace the pistons and it goes away.

    Seriously though, I have a 220k m52 thats been hammered on boosted for 5 years now. obd1 dipstick and a hose on the valve cover. I did port the m50 VC a little for more flow. At idle just some condensation comes out. Under full load theres decent air coming out containing an oil mist but were talking a spoon full or 2 over a track day.

    I have broken 2 sets of pistons in this motor over the years via knock and butting rings. Its always immediately obvious as the blow by gets really bad, it smokes, and compression test identifies the bad pistons.

  13. #13
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    Quote Originally Posted by CallMePuff View Post
    That sounds like it's probably unrelated to crankcase pressure, but you could rule it out with a compression test. I would think a breather filter on the crankcase would be fine. Is it the stock hose diameter? I would also assume that if it were
    too much positive pressure, it'd be pushing out of your seals.

    Is your oil drain straight down, no kinks? Is it put into the top of the oil pan or higher? Does your turbo require a restrictor in the feed? Is your compressor housing tightened down well? I'm not sure how else it'd be getting past the seals on the turbo.
    The drain is using a scavenge pump because there was no room. But the line has a U -an fitting then goes to pump then drains back down near the obd port. It’s not ideal, wondering if this could be an issue but the pump sucks the oil and I do not smoke. I have a BW S366 turbo with the fittings from boost monkey. The breather filter is a bit bigger than stock hose, would that be the issue?

  14. #14
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    Did anyone read that it said "Oil filter cap" If OP meant filler then the suggestions are inline with that but if he indeed meant filter cap then replace the o-ring and move on.
    1997 328is - Megasquirt PNP, Holset HX35, Deka 80lb injectors, SPA T3, Precision PW39 WG, Synapse Synchronic BOV, DKM Organic Twin Disc Clutch, Innovate LC-2 W/B, Mishimoto Intercooler, Mishimoto Catch Can, Mishimoto Rad, Devils Own Meth, Porsche 911 calipers with E46 M3 rotors, Corsa Exhaust

  15. #15
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    Quote Originally Posted by somebody5788 View Post
    Did anyone read that it said "Oil filter cap" If OP meant filler then the suggestions are inline with that but if he indeed meant filter cap then replace the o-ring and move on.
    Oo good catch. If it's leaking out of the oil filter housing, that's an easy fix and is unrelated to crankcase pressure.

    Sent from my Nexus 6P using Tapatalk
    '95 E34 525i, M50B32 (S52 Crank, K1 Rods, JE 9.0:1 Pistons, S52 Cams, Cutring, Achilles Oil Pump Shaft & Sprocket), GTW3684R 0.82A/R, ZF320

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