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Allan-Herbie

Murcielago throwing betlts?

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Had my car for 3 years with no issues. Then all of sudden the pully loosened and threw a belt. Since then we have replaced 2 additional belts as the pulley continues to loosen quickly and it blows the belt off. Any ideas? We torque it to factory spec, and it continues.

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Check the bearings on the pulley, it should spin freely enough you dont need an overly tight bolt.

 

Something is binding inside the bearing, spinning the inner race and causing the bolt to loosen.

 

Red loctite may help prolong the problem, but i suspect the next time it throws a belt the pulley will be seized completely.

 

Im a little surprised it spins in the direction to loosen the bolt. Typical practice with anything spinning is normal operation would tighten the bolt, even if it meant using a left hand thread.

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I had this, and so did Simon George with the high miler from Evo. The taper was worn inside the bottom pulley. A new pulley fixed the issue. There is no keyway or other mechanism to secure the pulley other than the bolt. The pulley is held tight on the taper alone by the bolt. If it's not the pulley that's worn, it will be the crank !! I understand however that this is rare, as the pulley is softer than the crank.

 

Also on mine, as I'd been through a couple of belts, the spacer with the long bolt that you have to remove to change a belt, on the power steering pump bracket frame, had become squashed. This meant that the idler pulley on the frame was out of line, and causing the belt to run out of true. I shimmed up the spacer to get everything back in line, and had another one turned at a later date.

 

Those are your problems !

 

 

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To clarify, I was talking about an idler pulley. Is it an idler or a fixed pulley (crank, etc)?

 

 

I knew what you meant Allan. :eusa_dance:

 

I hope you didn't impulsively get jiggy with the Loctite.... :o

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Power steering pump support frame,AC compressor,alternator 45 +/- 5 Nm

Guide pulley screw 49 +/- 5 Nm

Automatic tightener pulley screw 45 +/- 5 Nm

 

Sorry for the late reply, hope this helps

 

Also, for clarification, this is for Murcielago, if you need for Diablo let me know

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Check the bearings on the pulley, it should spin freely enough you dont need an overly tight bolt.

 

Something is binding inside the bearing, spinning the inner race and causing the bolt to loosen.

 

Red loctite may help prolong the problem, but i suspect the next time it throws a belt the pulley will be seized completely.

 

Im a little surprised it spins in the direction to loosen the bolt. Typical practice with anything spinning is normal operation would tighten the bolt, even if it meant using a left hand thread.

 

Just FYI, use blue loctite only and green if its a fine thread. If you use red, it will take a torch to get it off. Matter of fact I think it even says so on the tube. :icon_thumleft:

 

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