[explorerfriendly]

any one know why my 87 cherokee's I6 engine is whinning? it happends all the time and is very very slight but annoying. It also sounds like a diesel when going up hills or under fairly hard acceleration. i was thinking that the exhas manifold might have somthing to do with the whinning after reading other threads but any way to check that, or is there anything else that could be making that noise?
thanks,
nick