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Thread: Excessive crankcase pressure

  1. #1
    Original Gearhead Joe Morreale's Avatar
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    Excessive crankcase pressure

    I am getting too much crankcase pressure. It's causing a lot of oul to get blown out if the hot side vent. About and ounce every hundred miles. M.turbo recommends eliminating the PVC and drilling and welding 3/8" bungs, hooked to a single vent can. They also have instructions on how to drill the internal Chambers of the VC for less oil to be blown. Adding scrubbers inside the VC is also shown.

    I have no room on my firewall for a catchcan. I'm going to have to relocate the windshield washer tub. I see FM has a kit.

    All of this work will be for naught if the engine has a mechanical issue. I took a compression test, which was good, not to long ago. The car doesn't smoke at all. I'm going to have to do a leak down test. Never did one and none of the big box stores have the tester in their loaner packages, that I can find. If anyone has one and can help me use it at their place, I'll buy lunch.

    If it's a valve, I have a good head to replace it. If it's rings, I'll keep dumping oil in it until I can afford a new motor. My anniversary trip to Ashville sort of depleted most of my funds and I haven't gotten any work in months.
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    Events Manager minuteman048's Avatar
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    Re: Excessive crankcase pressure

    Quote Originally Posted by Joe Morreale View Post
    I have no room on my firewall for a catchcan. I'm going to have to relocate the windshield washer tub. I see FM has a kit.

    If anyone has one and can help me use it at their place, I'll buy lunch.
    There is a whole write up on this by AO back in 2011. Unfortunately Photo Bucket hijacked the photos from the forum.
    99 Emerald Mica, 01 Header, Ground Control Springs w/Bilstein HDs. Thompson CAI, High Flow cat w/Borla Exhaust, Fab9 COP's
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    Individual-1 ☚☻☛ Agent☣Orange's Avatar
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    Re: Excessive crankcase pressure

    Yes, Photobucket really screwed countless people on countless forums. I just don’t have the time or energy to recompose every writeup I’ve ever done over a decade. Insofar as Joe’s crankcase vent problem though, he could weld or thread a large AN fitting on the side of the valve cover and put a catch catch can anywhere he has space. I still prefer a catch can prior to venting to atmosphere otherwise oil vapor would coat everything in the engine bay.

    The stock Miata valve cover contains a labyrinth of passages the stock PVC system uses to keep oil internal before the PCV valve directs crankcase gasses back into the intake. With Joe’s turbo setup, even without knowing the results of blowby past his rings, I’d just skip the stock PCV system altogether.

  4. #4
    Original Gearhead Joe Morreale's Avatar
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    Re: Excessive crankcase pressure

    These are the parts I plan on using for my venting project. Both will use 3'8'' fuel line hoses. I just have to measure to make sure the catch can will fit, after the windshield reservoir is moved. I will also be opening up the hole, in the internal baffle to 1/4''. The pvc on the im and the original vc breather hole will be capped. Scrubbers will be put inside the internal baffles to hold back oil, yet ensure ventilation. I'll order the relocation kit today or tomorrow.



    https://www.summitracing.com/parts/sum-220072 bung to be welded in place of pvc and on hot side

    https://www.summitracing.com/parts/trd-2269 nipples for bungs and catch can

    https://www.summitracing.com/parts/aaf-all36109 catch can with breather vent

    https://www.flyinmiata.com/suzuki-ca...er-bottle.html
    2001 SE British Racing Green - FM frame rails - FM solid sway bar - FM clutch- Mishimoto 53mm radiator - Bilsteins -
    Complete MK Turbo kit with intercooler - 3'' custom exhaust - Custom door panels - Custom "shorty" console

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    Re: Excessive crankcase pressure

    I installed a new pcv valve and a one way valve right before it. Ebay sells them cheap. Make sure it’s a medical valve that is heat resistant. They have different ones. Check your charge pipes for oil to make sure it’s not the turbo, crankcase pressure is a different problem that will most likely get worse. Not sure it’s worth all the fussing and money spent. Try turning down boost a bit in the meantime. Still think rods only and new rings/hone would be a good direction for the new motor. That or keep the boost down.




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    Individual-1 ☚☻☛ Agent☣Orange's Avatar
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    Re: Excessive crankcase pressure

    Are you sure you don’t want to go bigger than 3/8ths? Also, I’d include a check valve in there somewhere. Last, get a few feet of washer fluid tubing for the reservoir relocation.

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    Re: Excessive crankcase pressure

    I installed a check valve in place of the PCV. It is open when not in boost and closes when in boost.

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    Original Gearhead pdexta's Avatar
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    Re: Excessive crankcase pressure

    I've run a Lowes Kobalt air compressor water separator thing, with an extra check valve (mine was a leftover brake booster check valve). If you google "Lowes/Home Depot catch can" you'll get some good results. Mine catches a decent amount of oil and I haven't had any crankcase pressure issues.

    That valve between the intake manifold and valve cover was never really intended to see pressures it sees on a boosted motor. If it's not holding a tight seal then all your boost is going strait into the valve cover. That's definitely the first thing to rule out before you go spending big money on tearing the block apart.
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  10. #9
    Original Gearhead Joe Morreale's Avatar
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    Re: Excessive crankcase pressure

    I couldn't find a breather that had 1/2'' npt outlets. I'm using a check valve with a GTX pcv now. I was hoping to buy time on a possible oil ring worn situation. Regular compression went fine. Maybe it's a valve leaking. At this point I really don't know.

    I don't have a garage to disassemble a motor. The money I had was saving to build a motor went away with vacation. Having somebody hone and ring my block, and assemble the top end is going to be out of my price range for some time. UK distributor is selling sub 80k vvt motors for $750 delivered. I can be satisfied with my power level. using stock rods, safely.

    I really need to do a leakdown to determine if the rings are leaking, or is it a valve. From what I read it's not too difficult. My neighbor has an air compressor that I can use. I saw a leak down kit on Harbor Freight website and it doesn't look like it will go all the way down the head to the spark plug holes.
    2001 SE British Racing Green - FM frame rails - FM solid sway bar - FM clutch- Mishimoto 53mm radiator - Bilsteins -
    Complete MK Turbo kit with intercooler - 3'' custom exhaust - Custom door panels - Custom "shorty" console

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    Events Manager minuteman048's Avatar
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    Re: Excessive crankcase pressure

    99 Emerald Mica, 01 Header, Ground Control Springs w/Bilstein HDs. Thompson CAI, High Flow cat w/Borla Exhaust, Fab9 COP's
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