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M50B25 NV massive oil issues

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    M50B25 NV massive oil issues

    Goodmorning folks,

    I have an issue with my M50 swapped 318i. I was driving around in it for a little bit when I noticed a huge amount of blue smoke. Like actually blinding traffic 200 meters behind me.
    The entire engine is rebuilt top to bottom but it still does the exact same thing. I checked the entire PCV system and it's fine. The engine is losing a huge amount of oil: 3 liters / 100 km.
    There is oil on the bottom of my car underneath the driver seat position. Nothing seems to be leaking ( something obviously is but I cannot seem to find it! ) and there is gasoline mixed with my oil.
    The oil cap smells like gas, the dipstick does and the oil drips off like it's water. The car also smells like gas and the exhaust which was fitted new a week ago is pitch black and dripping gasoline.
    I am mind blown and can not seem to find the issue. Yes it has new valve stem seals, new piston rings and a new headgasket.
    I changed the fuel pressure regulator which was leaky but that doesn't seem to fix the issue either.
    The smoke is just a normal damp gray ish color when idling and turns dark blue if you even slightly hit the gas and puffs big clouds when you floor it.
    I've been to a BMW dealer, a BMW specialist and a regular garage and they are all mind blown and can't seem to find it.
    I'm hoping one of you has any idea what could cause this because I'm on the brink of buying a new engine which I don't think will solve the problem because the engine itsself seems to be perfectly fine. Compression is perfect and it runs super smooth, but you can hear the oil is not doing its proper work as you can actually hear the gas taking away its lubricating function.

    #2
    Do a leak down test. If you have fuel in your oil, then the car was most likely running rich, washed the rings down and they lost their seal. Could be a stuck or leaky injector.
    john@m20guru.com
    Links:
    Transaction feedback: Here, here and here. Thanks :D

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      #3
      In rebuilt did you use m50NV piston rings? The parts shops normally sell m50tu piston rings to m50nv, because they don't know the difference. The rings fit, but will lead to huge oil consumption and smoking issues. M50nv actuallu uses same rings as m20. The engine will have good compression etc. with m50tu rings, but the oil rings are different and that's where the oil consumption/smoking comes.
      Last edited by pazi88; 01-26-2020, 03:41 AM.

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        #4
        I've seen water damaged dme's cause the injectors to go wide open. Check fuel pressure drop with the key on & off with the return line punched closed. If it's leaking that much fuel into the crankcase you can wipe out a bearing or score a cylinder wall quickly.

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          #5
          pazi88, you may be on to something. I indeed got different rings than the ones that were in the engine previously. However that worries me because the problem was the exact same with the old rings. So either those were worn and these ones are wrong, or those were right and it was something else and I've now put the wrong ones in. Hard to know but thanks!

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            #6
            caperix, I checked fuel pressure and its through the roof. Going to ask around to check with a different DME. Thanks!

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              #7
              forcedfirebird, I checked the injectors and theyre not leaking. They are however spraying in way too much fuel. I replaced the fuel pressure regulator but it hasnt helped at all.

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                #8
                pazi88, youre right mate just checked and Mahle sent me the vanos ones. For fucks sake!!!!

                Comment


                  #9
                  Originally posted by DamonH97 View Post
                  caperix, I checked fuel pressure and its through the roof. Going to ask around to check with a different DME. Thanks!
                  That's not an injector problem, that's a fuel- pressure regulator problem. This would certainly over- fuel your engine.

                  t
                  now, sometimes I just mess with people. It's more entertaining that way. george graves

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                    #10
                    How high was your fuel pressure? You said you replaced the regulator all ready, did you use a new one? You may have a pinched return hose preventing the regulator from working properly.

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                      #11
                      Originally posted by DamonH97 View Post
                      pazi88, youre right mate just checked and Mahle sent me the vanos ones. For fucks sake!!!!
                      Well at least you now know where the problem is...

                      Comment


                        #12
                        Originally posted by pazi88 View Post

                        Well at least you now know where the problem is...
                        Yes that's true, But now I don't know which piston rings I need. 84 mm or 84.25mm?

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                          #13
                          Originally posted by TobyB View Post

                          That's not an injector problem, that's a fuel- pressure regulator problem. This would certainly over- fuel your engine.

                          t
                          It has a new FPR. I checked all the lines and none are clogged or pinched, the return works just fine. The problem is in the DME as I swapped them out and it instantly stopped smelling like fuel. So the right piston rings and a new DME and were off again.

                          Comment


                            #14
                            Originally posted by DamonH97 View Post

                            Yes that's true, But now I don't know which piston rings I need. 84 mm or 84.25mm?
                            84mm if your engine hasn't been bored to oversize.

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