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Thread: Alternator belt, tensioner and crank pulley - easy method.

  1. #1
    Senior Member
    Join Date
    Jul 2011
    Stoke on Trent
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    Smile Alternator belt, tensioner and crank pulley - easy method.

    I have read some negative reports on doing this job, but apart from being a bit fiddly at times overall it is an easy task. Should take about 3 hours including tea breaks etc.
    Here’s how with Turbine’s Tips.

    Working from the top:
    1 Disconnect the battery negative terminal, Remove the engine top shield. Turn the steering wheel a little to the right – it will help later when replacing the pulley.
    2 Remove the turbo shield, 2 nuts , 2 bolts one down the back.
    3 Remove the top bolt from the alternator (13mm) freeing the cable bracket.
    4 Press and unclip the top alternator plug. (The push ‘Clip’ is to the RHS of the plug)

    Working from below:
    5 Jack up and remove the offside front roadwheel and the shaped shield to reveal the crank pulley.
    6 Cut the old belt to release the tension. Take note of how it is routed. (Pencil needed)
    7 Put the car in 5th, Can't progress without this.
    8 Put the wheelnuts back on to protect the studs and use a steel pipe, bar or even crowbar to jam the hub against the floor so that it can’t rotate. To jam it, rotate the pulley anticlockwise with a wrench on a pulley bolt until the bar is solid.
    9 Use an axle stand or build a pile of bricks to the same height as the pulley center. This will be used as a support when removing/installing the pulley bolts.
    10 Using a couple of wrench extension pieces long enough to reach outside the wheel arch. Undo the three pulley bolts using the axle stand or brick pile to support the end of the extensions and thus ensure a straight drive to the bolt heads. A bit of wood on top will protect the tools. I used an 18” torque wrench to undo the bolts. They cracked easily.
    11 The pulley will fall off. )
    12 Displace the rubber cap, undo the nut and remove the alternator power cable.
    13 Undo the two lower alternator nuts.
    14 Undo the tensioner spring bolt.

    Working from the top:
    14 Pull the alternator cables out of harm’s way.
    15 Carefully pull the alternator off the studs and place it as far back and right as you can. Be sure the shaped spacer stays on the studs.
    16 If you can, do remove the black alternator ventilation shield (4 nuts) as it will give you more room to work.
    17 Undo the 3 bolts securing the tensioner bracket and work the tensioner assembly carefully out the top of the engine bay. It’s not difficult. Don't snag the fuel pipes.
    19 Use an 8mm Allen key to remove the tensioner from the bracket. Fit the new tensioner.

    Installation is an EXACT reversal of the above with the following observations:

    - When putting the tensioner assembly back on THE NEW BELT MUST GO WITH IT. Ensure the belt is placed on the tensioner pulley ribs outward – or else ! This is a bit fiddly.
    - With the tensioner & bracket secured, and alternator refitted, work the belt into position from below, check its routing. This is fiddlier, like wrestling a worm.

    - Putting the crank pulley back on is a cinch.
    1 Place the new pulley on the belt and pull it gently backwards until you can get a bolt in - yes you can, there is no tension on the belt.
    2 Install this first bolt so that the pulley is still free to rotate on it.
    3 Using the same bar you jammed the wheel hub with in task ( above, rotate the wheel hub until the crank pulley boltholes line up. Install the bolts and nip them up.
    4 Jam the wheelhub again (opposite way) and using the axle stand etc tighten the bolts. Torque is as follows:
    Jaguar: tighten all 3 to 45 Nm and then finally tighten another 120 degrees or
    Ford : tighten all 3 to 100 Nm and then finally tighten another 90 degrees.
    I used 100 Nm and then 90 degrees as it’s easier to judge 90 degrees – it’s a quarter turn. )

    Other Torque settings that matter:
    Alternator bolt & nuts 47 Nm
    Alternator positive lead nut 8 Nm
    Tensioner bolts (all) 47 Nm
    Last edited by turbine; 07-07-12 at 17:15.

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  3. #2
    Junior Member
    Join Date
    Jul 2013
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    Hi, I did this yesterday and just thought I'd share my findings............

    Firstly it's a lot easier to do than it appears using this method - definately a DIY prospect for anyone with reasonable spanner skills.

    My car has 107,000 on the clock and I noticed when I was disassembling it that the job had clearly been done before but the bottom pulley hadn't been upgraded. When I split the tensioner assembly to bolt the new part to it I noticed that the muppet that had done the job previously had left the thrust washer retaining clip on the shaft. This is a thin metal spring that is clipped to the shaft of the new component under the plastic bolt retainer that you remove. The tensioner assembly is designed to rotate on the thin metal thrust washer not the clip which is just there to keep the thrust washer in place during shipping so make sure you remove it first. If you don't it will make the rotaion of the tensioner notchy and hence the tensioner pulley won't be able to track the belt properly as it runs past causing it to bounce slightly. This action will eventually lead to premature failure of the tensioner pulley bearing due to the repeated shock loading.

    I have to say the difference in the way the car drives is incredible, much quiter as you'd expect, but also much smoother to drive. The most remarkable thing is that I swear the engine now pulls better lower down the rev range and makes more power. I was wondering if the vibration caused by the faulty pulley might be being picked up by by the ecu as eccesive diesel knock and that the fueling and timing is altered to suit? I don't know if the engine has this ablitiy or even if it is fitted with knock sensors but the difference is quite marked - Is this all in my head?

  4. #3
    Senior Member
    Join Date
    Apr 2008
    North Wales
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    To prevent the engine turning For undoing crank bolts, its much easier to puta strong screwdriver into the brake disc vanes between te caliper.

  5. #4
    Junior Member
    Join Date
    Jul 2012
    Colchester Essex UK
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    Managed to do the job a couple of days ago in about 3 hours. The difference to the sound of the engine is quite remarkable, not only has it got rid of the rattle that made the engine sound like it needs replacing but it also got rid of the vibrations caused when the air conditioning pump kicked in. It was fiddly putting the tensioner bracket back on with the belt in place, I ended up putting one bolt closest to the nearside of the car in the tensioner bracket to begin which still allowed enough movement to feed the belt into position from below. Hopefully I won't ever do one of these again but I reckon I could probably do it within a couple of hours now if I had to.

    Many thanks for your guide it was excellent.

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