Knocking noise, maybe dying ac compressor?

Discussion in 'Engine, Gearbox, Exhaust and Air Intake' started by Barney626, Apr 16, 2018 at 5:51 PM.

  1. Barney626

    Barney626 Winner - POTM December 2017 Paid Member

    445
    Loughborough
    Clio 197 - Nimbus
    So did an oil change on saturday, everything went well car drove and sounded fine since then but this afternoon started the car and a consistent knocking/banging noise is coming from the engine bay.

    Not sure what it is and cant pin point where it's coming from. Engine hasn't lost power and the car still 'feels' fine, just this noise.

    Noise speed totally depends on revs. Doesn't matter is clutch is in or what gear im in. Doesn't change when I turn on/off the aircon.

    Any ideas on what it could be? Thought it may be either the AC compressor packing in or the alternator as it seems to be loudest when listening above the belt area...

    Best video I could get of it below. Can hear the regular whining of the engine and the distinct knocking sound that sounds like someone hitting an empty paint can with something...

     

  2. Foxspeed

    Foxspeed "the new red baron" Moderator

    disconnect a coil in turn & see if it changes/goes quiet...its a bad clip but sounds like it could be bottom end!
     
  3. Barney626

    Barney626 Winner - POTM December 2017 Paid Member

    445
    Loughborough
    Clio 197 - Nimbus
    Fairly sure it isnt anything to do with the cylinders as the car is still running fine and not being rough.

    Will try it anyway and also try to get a better video from engine bay.

    Just to confirm you can pull the plug out the top of the coil with the engine running to see if it changes?
     
  4. suj

    suj Gold Member

    549
    Birmingham / Warwick
    Nimbus Grey 197
    Yep, take out each clip from each coil separately.
     
  5. Barney626

    Barney626 Winner - POTM December 2017 Paid Member

    445
    Loughborough
    Clio 197 - Nimbus
    So just disconnected each coil. All four made the engine go lumpy so it isn't a dead coil.

    Tried getting another video moving my phone around the car a bit more. It's definitely loudest when you listen to the off side of the engine above the belt. Sounds like it's coming from the AC compressor area tbh.



    I know that the AC system needs a regas so maybe could be related to that if the gas carries the lubricant?

    If it does turn out to be a dodgy compressor, is it a DIY-able job to replace it if I only have jacks?
     
    Last edited: Apr 17, 2018 at 11:58 AM
  6. Barney626

    Barney626 Winner - POTM December 2017 Paid Member

    445
    Loughborough
    Clio 197 - Nimbus
    Will be driving a few hundred miles on this over the weekend so could really do with knowing whether it could total my engine or not if I don't get it fixed before then?
     
  7. Foxspeed

    Foxspeed "the new red baron" Moderator

    the pulling off a coil isnt to do with one being faulty it was more to see if the actual "knock" changed to help diagnose a knocking bearing

    if the air con is low the compressor will be free-wheeling - you can tell be looking at the end of it and seeing if the end plate is turning if not the electric clutch is not engaged

    to check drop the auxillar belt off & run it that way the alternator / compressor / idler are not rotating
     
  8. Barney626

    Barney626 Winner - POTM December 2017 Paid Member

    445
    Loughborough
    Clio 197 - Nimbus
    Tbh the engine turned too noisy to tell if it changed after a coil disconnect. Will try again but doubt I'll be able to hear anything.

    If it isn't turning could it just be the pulley? It looked like it was moving back and forth out axis by a millimeter. As far as I can see there is a small visual mark on the belt and every time that goes round once the noise 'knocks' once, so it's in time with that...

    Is there a guide to taking the belt off? Never done it before so don't want to miss anything important. What's the best way to get access to it?
     
  9. Barney626

    Barney626 Winner - POTM December 2017 Paid Member

    445
    Loughborough
    Clio 197 - Nimbus
    So tried having a better look at the aircon pulley and think the aircon might be stuck on? Not sure if this is the end plate you mean.

    Aircon is 'off' in both of these videos:





    Can also see the pulley moving around quite a bit...
     
  10. Barney626

    Barney626 Winner - POTM December 2017 Paid Member

    445
    Loughborough
    Clio 197 - Nimbus
    So just tried disconnecting the coils one by one again and the noise never went away.

    Also checked the obvious like oil level and whether the filler cap was tight on, no problems there.

    Will have the car up on jacks tonight and get the wheel arch liner off to have a look at the pulley system.

    The main question is, if it's just a noisy compressor or slightly loose pulley knocking can I drive on it for a few hundred miles without it ruining my engine? Obviously not ideal but won't be able to fix it before a trip this weekend...
     
  11. Barney626

    Barney626 Winner - POTM December 2017 Paid Member

    445
    Loughborough
    Clio 197 - Nimbus
    So had the wheel arch liner out and saw this on the belt:

    QEifJfa.jpg

    Trying to source a new belt for tomorrow, reckon that's what is making the noise?
     
  12. Barney626

    Barney626 Winner - POTM December 2017 Paid Member

    445
    Loughborough
    Clio 197 - Nimbus
    Can I only use an 'F4R belt' or is there a generic size I can use? Even as a temporary one until I get a genuine belt...
     
  13. Foxspeed

    Foxspeed "the new red baron" Moderator

    use the right belt if not it can be derailed/dragged in to the lower pulley and the timing jumps and bends your valves!

    when you fit the new belt MAKE SURE IT IS SAT IN THE PULLEYS/PULLEY GROOVES CORRECTLY or it can cause again serious issues
     
    Pav likes this.
  14. Barney626

    Barney626 Winner - POTM December 2017 Paid Member

    445
    Loughborough
    Clio 197 - Nimbus
    So got the new pulley in yesterday and sure enough the noise is gone.
     
    Gus and Big Ben like this.
  15. Foxspeed

    Foxspeed "the new red baron" Moderator

    when was the cambelt done as the aux belt is usually done at same time???
     
  16. Gus

    Gus Platinum Member

    176
    Oxford
    Clio 200, 182 Turbo
    Bet thats a relief !! glad its sorted for you.
     

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