Click for Ocean Alexander Click for MotorCheck Click for Perko Click for Abeking Click for Abeking

MTU 12v396: smokes when cold

Discussion in 'Engines' started by angelosauto, Sep 15, 2020.

You need to be registered and signed in to view this content.
  1. angelosauto

    angelosauto New Member

    Joined:
    Feb 18, 2011
    Messages:
    18
    Location:
    Hutchinson island
    1991 MTU 12v396tb93 1980hp smokes a lot when cold
  2. mapism

    mapism Senior Member

    Joined:
    Aug 9, 2008
    Messages:
    2,111
    Location:
    Sardinia
    They all do.
    If twin installation, any meaningful difference between port and stbd?
    You might consider a block heater, anyway.
  3. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    14,432
    Location:
    Fort Lauderdale
    This, they all smoke a lot when cold. They also usually have a decent amount of visible smoke under 1000 rpms also when warmed up. Also incredibly hard to get parts for.
  4. angelosauto

    angelosauto New Member

    Joined:
    Feb 18, 2011
    Messages:
    18
    Location:
    Hutchinson island
    Thank you I’ve been hearing that a lot lately, I’m used to my 92s which I’ve run and maintained over 10 yrs and burn very clean‍♂️ One quick puff cold and nothing at all after that, only had to use block heaters in New England winters and never in Fl
  5. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    12,649
    Location:
    Satsuma, FL
    What color is the smoke?
  6. angelosauto

    angelosauto New Member

    Joined:
    Feb 18, 2011
    Messages:
    18
    Location:
    Hutchinson island
    Greyish white you could see some fuel or oil film around stern of boat after I shut it down, but under load cleared and got up to rpms
  7. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    12,649
    Location:
    Satsuma, FL
    Un-burned fuel.
    Low compression, cold block, leaking injectors.

    In south FL, block heaters usually is not a norm. If you have them, turn them on several hours before starting. See what happens.

    I'm leaning towards leaking injectors.
    When was the last injector service? Not replacement but in the shop, tested and popped.
  8. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    14,432
    Location:
    Fort Lauderdale
    The 396's have nozzles.
  9. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    12,649
    Location:
    Satsuma, FL
    Nozzle, Injector ;
    If they leak, it's not rite.
    Quickly found a corny kid making a video with a crack pump.
    Not to technical but gives you a good idea.

    At 6:00 gives you one example of leaking.


    Another issue is just leaking when not running. A few extra drops in the lung and exhaust manifold takes a while to clear out.

    Before our 12V71 rebuild, our smoke could block the sun, worst than old misquote control trucks.
  10. angelosauto

    angelosauto New Member

    Joined:
    Feb 18, 2011
    Messages:
    18
    Location:
    Hutchinson island
    I don’t know I’m thinking of buying boat and asked to fire it up cold and to me didn’t look normal but then again I don’t know much about MTU396 engines other than they’re pricy, but been told by a few people that it is common for them to smoke under 1000 rpm and just seemed odd, I thank everyone for their input and experience with them.
  11. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    14,432
    Location:
    Fort Lauderdale
    They typically smoke A LOT on cold start up. Typically white/grey smoke. It thins out when they get warmed up. But given the price and cost of servicing these old dinosaurs, I'd avoid any boat with them unless it's a smoking deal.
  12. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    12,649
    Location:
    Satsuma, FL
    Sounds like a Smoking Deal already.
    Walk on.
    When I was shopping for a whole 396 engine for a Hatteras project boat a few months ago (blown, not rebuildable), GoldCoast Power found a set out of country and one on the left coast. Running take outs. Near cheaper for the ones over seas, freight and a spare.
    Shame, they gave that fancy Hatt 60 away to get rid of her.
  13. angelosauto

    angelosauto New Member

    Joined:
    Feb 18, 2011
    Messages:
    18
    Location:
    Hutchinson island
    Was that the one on east coast that owner was living in, and engine blew when they sea trialed it, think it was a 65EB I was supposed to look at it right before it blew apart think it sold under 50k
  14. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    12,649
    Location:
    Satsuma, FL
    Yep, sold way cheaper than that.
    I did get a bid in, was going to scrap her.
    More info in the Hatt rag.
  15. angelosauto

    angelosauto New Member

    Joined:
    Feb 18, 2011
    Messages:
    18
    Location:
    Hutchinson island
    What did it eventually sell for? Are they repowering or just replacing blown block
  16. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    12,649
    Location:
    Satsuma, FL
    $20k
    Boat & Breakfeast.