3.0 m3 engine

Thread in 'Technical Questions' started by eager, Oct 12, 2008.

  1. eager

    eager Member

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    Just a curious one. Do 3.0 m3 non evo engines generally sound a little rough ? a bit tappity ? Or should they run very smooth ? :thumbs:
     
  2. Mike@TDSW

    Mike@TDSW Active Member

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    They do sound quite tappy/rattly compared to other smooth as silk bm 6's yeah. Obv within reason.
     
  3. eager

    eager Member

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    Was just curious. Had a rummage around one today. Just thought straight 6's generally liked to run pretty smooth. didnt sound bad, just not what expected
     
  4. eager

    eager Member

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    What oil do you lot put in these ? type/weight/quantity. Normal road use :)
     
  5. Mike@TDSW

    Mike@TDSW Active Member

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    Thats something that gets debated often on BM forums as apparantly BM sent a memo out a few years ago with updated oil type for m3 engine. Something horrendously thick.
    Some use what they reccomend, some use what they think is best, some BM garages reccomend different to others. Iirc I used 5w40 Mobil but its a long time ago now.
     
  6. 20vWill

    20vWill Active Member

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    Any decent 5W40 synthetic oil.

    They are usually slightly louder from cold, it's just the solid followers/shims, they quieten when warm (as everything has widened-out a little, so all in exact tolerance then), but still a little ticky, and whirring VANOS units is all normal. It's a 100 bhp per litre race engine so make allowances.

    If it's real loud, the valve clearances need adjusting. BMW charge around £450 for this. I will do it better for less haha.

    Many S50's get this overlooked as it is time consuming and a pain in the ass to do. Don't though. You must do it.

    It should idle OK, but they are rarely butter smooth. Sorting any vacuum leaks, keeping the ISCV clean and keeping plugs fresh all helps idle.
     
  7. eager

    eager Member

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    Much to setting valve clearance ? It looks like someone has been in there recently. Shiny bolts along the rocker and around top of engine..apparently was serviced recently but no stamp.
     
  8. 20vWill

    20vWill Active Member

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    Yes. A special tool, shims, vernier calipers, time, patience, accuracy, a new cam cover gasket.

    Even if someone "has been in there recently", it doesn't mean the job has been done right!! Inaccuaracies as low as 2 hundredths of a millimetre can cause excess noise.
     
  9. amiga

    amiga New Member

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    I haven't heard how those engines run but it certainly can be a clearance issue. It can made hell a lot of a difference when shims are correct. Engine will get a lot quieter and I reckon can get some power gain as well due to correct valve lift, timing etc. Wouldn't a feeler gauge be handy to do it?
     
  10. Sport Coupe

    Sport Coupe Dori BMW Stylee'

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    It's amazing what a difference the shims being done correctly can make to the S50 engine, especially if you get custom ones made for the exact thickness you require.
     
  11. 20vWill

    20vWill Active Member

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    Erm there's no need to be THAT posh! Usually if you have a few used ones around, they may be worn by the odd hundredth of a mil, so you can swap them round without needing to buy too many more.

    There's no need for custom ones or even surface grinding to get them exact... the tolerances allow for the 0.05mm steps of shim-size to work fine in any situation. Mine's real quiet now.
     
  12. Sport Coupe

    Sport Coupe Dori BMW Stylee'

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    Perhaps that's just my attention to detail, but I like to think that you only get out what you put in.
     
  13. 20vWill

    20vWill Active Member

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    so what was the "perfect" clearance you aimed for and why?

    Spec is 0.28-0.33mm on the B30. Anywhere in there is gravy. I pay more attention to detail than most but I won't be getting the sandpaper out anytime soon ;)
     
  14. Mad Cas

    Mad Cas wrecked

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    Most BM sixes I've heard tick like a bastard. Often the injectors though.

    Never a patch on the ford HCS though :smash:
     
  15. eager

    eager Member

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    Is the single vanos noise basically a whirring/tappy noise that happens when say you pull the throttle cable to rev it up then let go...and when the revs start to fall back by themselves you get the noise ? That sound like needs the clearance set or something more sinister ?
     
  16. 20vWill

    20vWill Active Member

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    That sounds exactly like normal VANOS mechanical noise.

    Gay BMW owners get really scared when they hear any noise. An example would be: "Ooooh I heard a noise from my rear suspension. Does this mean my VANOS is fooked?" But it's really nothing to worry about.

    Solenoids on the VANOS unit can stick, the result will usually be a car that feels good at higher revs (3000+ rpm), but jerky at lower revs, part throttle and very dodgy idle. Even then that is still nothing much to worry about on a track or drift car. Not great on a daily town driver though.
     
  17. eager

    eager Member

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    Yeh just that was the noise that made me wonder. It gets a bit faster with more revs put on...but a quick raspy rev and let it idle its way back down you hear it being a bit raspy. Vanos ? And normal/not ready to fall apart ?

    Any other weird noises i should listen for ?
    Also, do dakar yellow love to fade badly ? Im told they do by owners of them. Just wondering if this one needs a good polish. It drives very straight, paint looks original,HPI clear. just cautious
     
  18. 20vWill

    20vWill Active Member

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    Sounds like you want me to do an inspection on it via the internet or something...
     
  19. Sport Coupe

    Sport Coupe Dori BMW Stylee'

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    I'm no engine builder and have not played around with them enough to give you a qualified 'perfect' clearance figure to aim for. But due to the engines nature of being quite highly strung I therfore accept that it rattles due to its state of tune and the fact that the cam has steep flanks. I generally aim for all my values to be the same figure at the wider end of the manufacturer tolerance parameters, at the possible expense of some minor valve train noise.

    As you imply, doing the procedure correctly and to within specification is more than enough to ensure a well maintained and performing vehicle.
     
  20. 20vWill

    20vWill Active Member

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    Pretty much the same here, hence why I measure every shim rather than just take it's printed value, so I can select the best for each valve for the closest spread.

    This is a little sad though. We should talk about girls or something now.
     

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