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Possible solution to oil consumption/smoking from exhaust

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    Possible solution to oil consumption/smoking from exhaust

    I have an obd1 s52 with m50 manifold. For a while now I have experienced a strong oil smell with a smoke cloud when taking off from stoplights. This only occured when the engine was warmed up and after sitting at a light and idling for a while. Due to the symptoms, I suspected possible valve seals/guides. I have actually replaced my cylinder head with one from an m52 that I had resurfaced, checked valve guide wear, and replaced the valve seals. I have also tried various ccvs including the m5 cyclone separator and the obd2/m52 ccv. I have also tried piston/solvent soaks in an attempt to clean up my oil control rings. These things did help a little, as originally I was getting ridiculous smoke clouds upon decel/engine braking when coming at a stop. After trying these things it went back to just the smoke clouds after idling for extended periods of time and taking off. Recently I stumbled upon a common mod on e46s to delete the ccv system and just run a catch can with pcv valve, basically applying much higher vacuum to the crankcase.

    It seemed sketchy to me at first but a lot of people seemed to have success with it, and since it was a simple mod to do I figured I would try it. I've been running it for about a week now and the change has been drastic so far. The engine runs smoother and seems to pull harder. It doesn't matter how long I sit at lights now or how hard I punch it. I can't get it to put out any smoke cloud in my rearview. I have the valve cover hooked up to a catchcan and then to a tee between my icv hose and the intake manifold. I already had this tee installed from my last setup (obd2 oil separator), since I copied the RMeuropean method of cutting the icv hose in half and installing a tee to install the obd2 ccv system.

    I am aware there is some risk involved with this setup, as I have read with high vacuum on the crankcase the oil pressure can drop, and oil can actually be pulled away from the rings and piston wrist pins. I believe my oil control rings may be the main cause of my smoking and oil consumption, and that could be why this has been so effective in stopping the symptoms on my engine. Either through helping the oil rings seal better, or through the vacuum preventing oil from being sucked up past the rings. So far I have only had positive results. The car honestly feels as strong or stronger than when I first did the swap years ago. As far as oil consumption, I haven't driven it long enough to tell if there will be a difference. I have been burning about 1 quart per 1k miles for a while now. I will see how it looks when I reach the next 1k miles. Hopefully nothing crazy happens to my engine by then.:shock: Anyways I just wanted to share my experience as this was a big surprise to me, and if it continues to work this well then I will be a very satisfied driver.




    #2
    well looks like i spoke too soon. i have noticed while sitting at hot idle for a while my oil pressure light will sometimes flicker. I am going to disable the vacuum until i figure out a way to lower the vacuum level a little and try again.

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      #3
      well in case anyone is interested i have found a way to lower the vacuum to a level i am happy with. also i got rid of the catch can. after driving with the catch can for about 400 miles i had zero measurable oil inside of it. i took out the drain plug and shook it around and waited for about a minute. i didn't even get a drop out of it. and i didn't have any filter media inside of it, only a makeshift steel plate baffle down the center. this seems to be inline with what the e46 guys report, with very little oil collecting after the ccv delete. so it seemed pointless to me to have more clutter in the engine bay, along with a need to empty the can when winter time rolls around. so today i got some fittings and hooked the vacuum back up to the crankcase, with the hose from the valve cover straight to the pcv valve and then intake manifold vacuum. then i measured the vacuum to the valve cover with a mityvac and got right around 7.5" of mercury. then i took another tee and installed it with a 1/8 hose going to the intake boot. this small diameter hose allows the intake manifold to still pull a vacuum on the crankcase through the bigger valve cover hose, but bleeds off some of the vacuum since this hose goes to the air cleaner elbow/boot. in theory this could cause idle issues because it is sucking air in from the intake hose and bypassing the throttle plate, but in practice so far i have not noticed any noticeable difference in idle quality or speed. with this smaller hose tee'd off to the intake boot i measured vacuum again and saw right around 2" of mercury. when pulling off the oil cap there still seems to be a pretty strong suction, but less than before when there was only the one hose and pcv valve to the valve cover. the setup i have now is essentially the inverse of the stock obd1 breather setup. whereas the oem setup has the small hose to vacuum from the icv fitting nipple and a larger hose venting to the intake boot, this setup has a larger hose/ larger volume going to intake manifold vacuum, and smaller breather hose to the intake boot. i could not find a spec for the e36 oe ccv vacuum measurement, but would imagine its close to the m54. the m54 appears to be 3-6 inches of water. a google conversion shows 6 inches of water to be .44 inches of mercury. so i am now over 4x the stock vacuum spec, but over 3x less than i was before. i have not driven long enough to know yet if there will be any more issues, but so far i am not getting any more oil pressure light flickering. and the smoking after sitting at stoplights is once again gone. i will report back after driving for a while with any good or bad news

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        #4
        Hmmm... interesting info.
        I also experience some blue/black puffs of smoke but only on deceleration while still in gear, nothing when in neutral. I wonder if doing similar setup to yours would solve the problem. I have OBD2 S52 with OBD1 intake manifold and fuel rail. I did replace OBD2 oil separater with new oem Bmw part. Would you mind drawing a diagram of some sort to help me understand the new setup you got. It would be much appreciated. Thanks for your post.
        Paul
        "i love vee tek, its a wonderful sound when you driving right by it"

        If you bought anything from me, please leave a feedback here: http://www.r3vlimited.com/board/show...ghlight=drulle

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