The belt tensioner on my 95 was totally shot. Search this forum for my recent post on this. Dont neglect this. Easy to evaluate while you're in there. Check status of the tensioner arm and make sure the pivot pin isn't damaged.

My 95 groaned too. I didn't positively Identify the issue but it hasn't since I replaced the thoroughly worn down voltage regulator - another easy fix.

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2009 E320 Bluetec 117,000
1995 E300D 306,000 Sold
1996 Ford Taurus LX 130,000 Sold
1985 300TD Still 225,000 Sold
2016 Ford Fusion 24,900