Grinding noise when cruising
Hi everyone, I bought a 2003 Grand Cherokee a few weeks back, 2.7 diesel after owning a 1997 4.0ltr petrol.
I have recently found that when I steadily cruise at about 40mph the revs drop AND climb making the car seem to hold back and then let go once the revs go back up but this is a constant up and down until I get the hump and slam my foot on the accelerator. This symptom is coupled with a kind of grinding noise coming from the underneath of the car. Overall the car is nice and tidy and when the accelerator is floored it picks up well.
Has anyone had this problem before or know what it could be? I've done a bit of research and it seems a few people are saying it could be the pinion bearing, apparently not what I want to hear and some people have said it's as simple as securing the transfer case. Any help would be greatly appreciated.