Nissan Repair: nissan terrano repair, nissan terrano, rotating assemblies

Question
I have a 91 nissan terrano and it makes an intermittant grinding noise from what appears to be the front. It is not the air con compressor and seems to only happen over 40mph and is not gear or engine speed related

Answer
Roy,

If the compressor is not intermittently locking that is making the noise then I would look at the idler pulley and other rotating assemblies.  Loosen the belts and spin the pulley by hand.  Do this to all the pulleys and see which is grabbing.  Also, since they are sealed bearings you can check to see if there is evidence of grease leaking out of them.  Naturally, you will want to look at the waterpump.