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BMW E46 318i intermittent blue smoke

Discussion in 'Motors' started by Phaser, 14 Mar 2015.

  1. Phaser

    Wise Guy

    Joined: 17 Mar 2004

    Posts: 1,562

    Evening chaps,

    I purchased a 2004 BMW E46 318i touring today. I've spent all week looking at coupes and saloons which were in all sorts of states. At one of the last ones today, I loaded up Autotrader to see what else was nearby and up came this touring a few miles away, figured I had nothing to lose by checking it out.

    Anyway, all looked good - clean arches, 4 decent premium tyres, FSH, 11 months MOT, xenons, bluetooth etc. 108k on a 53 plate. Wasn't my original choice but it's only going to be a work hack. Paid £1800 with the garage agreeing to do an oil service (showing 3k left on the dash).

    Drove fine on the (short) test drive, thought it was surprisingly smooth and quiet for a 4 cylinder (also have a 3.0 z4 with the m54). Didn't notice any smoke but I was on fairly busy unfamiliar roads and focusing more on that.

    Driving home I noticed the occasional puff of blue smoke when setting off after idling. My Dad was following and he said although it wasn't often, when it happened it was obvious. I'm actually in the process of getting rid of my old Focus due to worn piston rings so blue smoke was the last thing I wanted to see!

    It doesn't smoke upon startup, or idling, just when pulling away in first gear and very occasional in gear under load - and not all the time either.

    Is this likely to be the piston rings / worn stem valve seals or could it be something like the PCV / oil breather pipes?

    Initially thought of ringing the garage up on Monday and handing it straight back. I'd like to take it to my usual BMW indie and get his opinion but reluctant to fork out any money if it's going back.
    Last edited: 14 Mar 2015
  2. teenwolf


    Joined: 25 Jul 2010

    Posts: 4,007

    Location: poop... letterbox

    Blue smoke is oil,
    Cracked piston maybe
    Valve stem seals or ccv

    Sounds expensive either way
    Last edited: 15 Mar 2015
  3. pepsilol


    Joined: 26 Jun 2011

    Posts: 4,900

    Prob valve stem seals as those engines have nothing to them really.
  4. Jono8


    Joined: 20 May 2007

    Posts: 33,189

    Location: Surrey

    Good luck with that!
  5. Hades


    Joined: 19 Oct 2002

    Posts: 24,963

    Location: Surrey

    My first thought was valve stem seals too. This is normally characterised by a small amount of blueish smoke on the overrun (ie when coming off the throttle) or when pulling away. I'd also expect to see some at startup although you don't say that is happening.
  6. Dogbreath


    Joined: 18 Oct 2002

    Posts: 16,653

    Location: Devon

    If it's genuinely smoking under load then it's less likely to be the valve stem seals and more likely a PCV/breather problem. If it's just a puff of smoke when you open the throttle, rather than continuous, then stem seals or rings are probably the cause.
  7. GeX


    Joined: 17 Dec 2002

    Posts: 6,462

    Location: Manchester

    Go back to the garage. You paid a premium to get it from a trader so take advantage of the few benefits that that brings. It's got a fault, take it back and ask them to fix it.
  8. shifty_uk


    Joined: 27 Sep 2004

    Posts: 12,913

    Location: Glasgow

    Is the 318 turbocharged?

    When my turbo failed, blue smoke was a result.
  9. Scania


    Joined: 25 Nov 2004

    Posts: 24,469

    Location: On the road....

    No, it isn't.

    Google "Oil separator valve" I had this replaced on my e46 318 when it smoked slightly on over run. If this doesn't cure it then it's most likely valve stem seals.

    I'd try with the garage you bought it from, the onus is upon them to prove the fault wasn't there prior to you buying it.

    Another thing, this is why short test drives are useless when weighing up a used car.
    Last edited: 15 Mar 2015
  10. Phaser

    Wise Guy

    Joined: 17 Mar 2004

    Posts: 1,562

    I've done a few small short journeys since but haven't seen much blue smoke. In some ways I wish it was a constant thing as I'd then be able to prove it by just turning up with the car and showing him.

    Update - spoke to the guy today who confirmed with his mechanic that the oil change was carried out with the correct oil (5w 30 fully synth).

    However the oil service is still showing 4600 miles, even if they hadn't used the long life stuff I'd have expected a longer range than this?

    Regarding the smoking he came back to me saying he'd spoken to BMW and they'd suggested replacing the oil separator valve and associated pipes which he said he'd ordered and will replace. I'm not holding my breath that this is the culprit as I believe this is more of an issue on the m54, plus I don't have any of the usual symptoms that goes with that such as bad idling etc.

    Back at work tomorrow which means a 25 mile run each way so I'll be able to get a better idea of how often it's happening. I don't want to start piling miles on the car or run the risk of it getting dinked in car parks etc if it ends up going back as it's only going to make it harder to get my cash back.
  11. jono_astra


    Joined: 4 Jan 2014

    Posts: 540

    Location: ....

    Last edited: 4 Mar 2017
  12. thepharcyde


    Joined: 17 Mar 2004

    Posts: 8,258

    slight throttle will not alway show the smoke. If you floor it you should see it if it's vsos
  13. Phaser

    Wise Guy

    Joined: 17 Mar 2004

    Posts: 1,562

    I've tried the find a hill and coast down in third, then floor it (to create the blowback vacuum) and no smoke. I understand this is the best way to prove it's the valve stem seals?

    Tried putting it in a higher gear so it's properly under load and no smoke either.

    The only time it's appearing is when you set off after being stood at traffic lights etc and pull away in first.

    You do get a faint smell of oil as it's ticking over though?

    I thought that however when I saw it earlier in the week it was showing ~3400 miles. I know it's condition based so the numbers can change however I wouldn't have thought it'd jump 1000+ miles when in theory the car would have been stood...
  14. Phaser

    Wise Guy

    Joined: 17 Mar 2004

    Posts: 1,562

    Dropped the car off with them this morning, they've just rang saying they've fitted a new CCV and replaced all associated pipes, and as a result there's no more blue smoke.

    The guy said it's been up to the local MOT centre and had an emissions test done too which it's passed. Print out available.

    Off to pick it up in the morning, fingers crossed!
  15. Scania


    Joined: 25 Nov 2004

    Posts: 24,469

    Location: On the road....

    Nice one, it should be just fine now as mine was after its got replaced - until some plastic part of the cooling system goes brittle and becomes a seive - that was the other bugbear of my 318i