Engine sounds like it is over revving

[Derelict-UK]

I have been driving (normally, 1.5 dci 80) and my engine sounds like it is over revving but the rev counter appear normal, there is a muffled revving sound coming from the engine and it does feel slightly off but drives okay.

Any ideas? Would ideally like to catch the problem sooner before it koncks out lol

 

[Derelict-UK]

If anyone is remotely interested, it ended up being the passenger side rear wheel bearing and cost £40.00 parts & Labour. Problem fixed.