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Engine guides and mods

451 CDI Alternator Belt Change

Modification Details

Getting The Old Belt Off

Take a 15mm spanner and under the alternator tensioner nut and swing the alternator down.
The old belt can be removed (if you don't have AC, if you do, remove that first) and the new belt fitted.

Re-tensioning The Belt - The New Way

This is the tensioning tool I bought from eBay from member okkerseel 

It sits against the crankshaft pulley and the alternator pulley. As you turn the wing nut, it pushes the alternator.
When the belt gets tight enough that you can move it about 8mm, tighten the alternator adjuster bolt.

Remove the green tensioning tool, jack the engine back up, bolt the engine mounts back up and
run the engine to see if it sounds ok and that the alternator is charging properly, click here.

If it's all OK, refit everything and go for a drive.

It is possible to get a perfect tension on this belt be measuring the frequency of the sound made by the
belt as you twang it. I haven't looked into it enough to be able to pass any info on but I do, I will.

Re-tensioning The Belt - Original Way

Place a 15mm spanner onto the nut and an E10 socket onto a torque wrench and onto the end
of the bolt. Set the torque wrench to "undo" and dial in 45Nm. Push the handle of the torque
wrench and the alternator will pivot up and the belt will tighten. When the torque wrench
reaches 45Nm you can tighten the adjuster nut with the 15mm spanner.

This should tension the belt properly.

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