V6 Engine loud knock idling & below 2000 rpm

  • Hi Guys, I have a loud knock/tick when my engine is idling and in drive when I rev to over 2000 rpm it stops completely, the car still drives fine engine runs sweet as a nut and pulls lovely but as soon as the revs drops below 2000 rpm it sounds like a tractor its so annoying I don't suppose anyone knows what the problem could be???

    Many thanks in advance

    Tim :)

  • Could be timing belt tensioner, do you feel it slapping off the timing belt cover? Be careful with your hands checking. Its located above the crank pulley to the left.

    Another common one is the friction gear spring on the rear exhaust cam. Notorious for slipping and causing a clacking sound. Was superseded by a keyed design that prevents slip. Quite annoying to replace though.

  • heres a video of the problem, many thanks for your reply I did reply myself but my post has gone :(

    here's the vid

  • Any progress? Replace the tensioner/ timing belt kit?

  • Still not 100% sure if it's the tensioner but I finally got chance to have a look today before it got dark, I've removed most the screws off the timing belt cover, I just can't get it open enough to have a look in but the pitch tone of the knocking does change when I crack open either end of the cover so I was thinking that may be the problem.

    I'm going to get stuck in to it tomorrow and get the car up on the ramps, I've got this family court thing on at the mo and just got all the paperwork out the way so have got time to get it sorted, I've so missed driving her can't wait to get her back on the road.

    How does the tensioner operate and do you know of any videos on how to change the timing belt ect I can't find that many at all, many thanks for your help it is much appreciated :)

  • After looking on the mx6 forums I've found 5 videos with the exact same noise as mine makes and they all said its the friction gear spring, where is it on the engine I've just had a listen again and the noise seems like it coming from the top left of the engine I'm having second thoughts now about the belt tensioner as from what I can see the timing belt runs nice and smooth, you mentioned it was a bugger to change, how would I go about it?

  • Try putting a screwdriver to your ear and touch it on the rear left of the engine valve cover, this should help you find the source.

    FGS require removal of the rear cams (and therefore timing belt too). It's not awful but it is a step up from a timing belt job. Also need a big adjustable spanner for undoing the mega nut on the FGS.

    -timing belt off
    -rear valve cover off
    -lock cams with a big spanner (via the hexagonal middle section)
    -undo the cam pulley bolt
    -undo cam caps in order of v6 manual
    -take out cams
    -undo the big nut on end of camshaft
    -replace with new design FGS

  • You make it sound so easy lol, Excellent, thats great many thanks for your reply, cant wait to get stuck in :)

  • Haha it is just adult Lego. Do you have the v6 workshop manual? Should be a link to it somewhere on here. If not there's an online version on mx-3.com


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