5.9 ZJ Ltd, 180k. Having a terrible grinding/scraping/whining sound from 5.9 engine in 98 ZJ Ltd. Anybody recognize it? Using hose as stethoscope, seems loudest near water pump, but no weep and no cooling trouble, and pump is only a year old. Friends advised belt tensioner, so I changed that with a high-quality replacement and no change. Grinding sound is worse under acceleration, goes away at idle when engine is hot. No performance problems, no smoke from tailpipe. Oil is fine. Just this awful sound. Grateful for ideas. Can water pump pulley fail on its own? Can’t isolate sound to any other belt component or area of engine.

 

I own a 01 GC/WJ(orig owner) with 189k. In its life time I have replaced the belt pulley and idler tensioner twice- both at the same time. When the belt pulley was failing is was a “squeal”. When the tensioner pulley was failing it was a “scraping” sound. My opinion is when one fails you replace all pulleys.