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How to tell a non-interference engine@

Discussion in 'Motors' started by wijcc, Jan 21, 2009.

  1. wijcc

    Wise Guy

    Joined: Aug 10, 2003

    Posts: 2,454

    Location: London

    How can you tell if the engine in your car is an non-interference engine so if the cambelt snaps it will not damage the engine?
    Thanks guys :)
     
  2. paradigm

    Caporegime

    Joined: Aug 26, 2003

    Posts: 32,724

    Location: Staffordshire

    Can the pistons hit the valves if the valves are down and the piston up?

    Yes - interference.
    No - non interference.

    Externally it would be impossible to tell. You'd either have to know or not.
     
  3. wijcc

    Wise Guy

    Joined: Aug 10, 2003

    Posts: 2,454

    Location: London

    ok thanks, is there any online sources that can tell if the engine is a non-interference engine?
     
  4. Clarkey

    Capodecina

    Joined: Oct 18, 2002

    Posts: 17,357

    Location: Wolverhampton

    which engine and i'll tell you.
     
  5. wijcc

    Wise Guy

    Joined: Aug 10, 2003

    Posts: 2,454

    Location: London

    1998 mitsubishi 1.6L (from carisma glxi)
    1999 mazda 1.5L (from 323 lxi)

    thanks :)
     
  6. Clarkey

    Capodecina

    Joined: Oct 18, 2002

    Posts: 17,357

    Location: Wolverhampton

    both of those are interference design.
     
  7. Nebzor

    PermaBanned

    Joined: Jun 18, 2007

    Posts: 1,576

    Location: Plymouth

    Am I correct in thinking that non-interference engines therefore have less compression than equivalent engines that have interference?
     
  8. Clarkey

    Capodecina

    Joined: Oct 18, 2002

    Posts: 17,357

    Location: Wolverhampton

    that, or low lift cams.
     
  9. Dogbreath

    Capodecina

    Joined: Oct 18, 2002

    Posts: 16,473

    Location: Devon

    This is not always the case, but designing around this does tend to require compromises such as deeper piston cut-outs.
     
  10. ShakenNstirred

    Sgarrista

    Joined: Jun 5, 2003

    Posts: 8,818

    Location: sawley/ long eaton

    mine`s camchain :D
     
  11. Clarkey

    Capodecina

    Joined: Oct 18, 2002

    Posts: 17,357

    Location: Wolverhampton

    which can still fail...
     
  12. ShakenNstirred

    Sgarrista

    Joined: Jun 5, 2003

    Posts: 8,818

    Location: sawley/ long eaton

    true but a lot less likely, than a belt
    your more likely to have a chain tensioner fail than the chain it self
    you would have to be very unlucky to have a chain fail(thats why its service life can be over 200k)
    or the life of the engine
     
  13. amigafan2003

    Capodecina

    Joined: Jan 18, 2008

    Posts: 11,528

    Location: Fylde Coast, Lancashire

    Tell that to 24v Cosworth owners :)

    To tell if your engine is interference, remove the cylinder head, put no.1. piston to tdc, place 2mm of plastacine on the top of the piston, place cylinder head back on and replace bolts but leave them 5mm from tight, get a spanner that fist camshaft pulley(s) and cut it in half (this is important) - now turn camshaft through 360 deg - stop immediately if the head seems to lift slightly or it suddenly gets harder to turn, lift cylinder head and see if there are any marks on the plastacine - yes - interference, no - not interference.
     
  14. dalin80

    Mobster

    Joined: Apr 20, 2007

    Posts: 3,447

    or have a look in autodata which will take 1/1000th of the time.
     
  15. wijcc

    Wise Guy

    Joined: Aug 10, 2003

    Posts: 2,454

    Location: London

    thanks guys :)
     
  16. paradigm

    Caporegime

    Joined: Aug 26, 2003

    Posts: 32,724

    Location: Staffordshire

    Tell that to DRZ, who had his fail on his BMW 525i.
     
  17. Sone

    Sgarrista

    Joined: Oct 18, 2002

    Posts: 7,572

    the nissan 1.5 engine in the Almera seems to have huge chain problems aswell
     
  18. Lopéz

    Man of Honour

    Joined: Oct 17, 2002

    Posts: 25,488

    Location: LE9

    This ^^
     
  19. Lashout_UK

    Capodecina

    Joined: Mar 2, 2004

    Posts: 11,113

    Location: SE England

    Cut the cambelt then try and start it.

    (nb. Don't do this)
     
  20. BigglesPiP

    Capodecina

    Joined: Mar 8, 2006

    Posts: 13,229

    Location: Chandlers Ford

    Not true, Escorts like to fail, the fools didn't use a siamesed chain.



    You can try turning the camshaft by hand, with a piston at TDC when you have the belt off. Non interference engines tend to have 2 valves per cylinder too.
     


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