Knocking noise from engine on 95 2.3t SE

[Jonboy123]

I have just bought a 2000 W, 95 2.3t SE 4 dr Manual transmission car. When I got it home, I noticed a knocking noise coming from the engine. I have taken it to a local specialist who said that it sounded like top end noise. The oil was quite low and he told me that he thought that dropping the sump, cleaning the sump filter would probably cure it. It hasn't though!
The car has done 102K and has a full main dealer service history. This guy did the latest service also. The knocking sounds like it is coming from a valve. The specialist said that it would be quite expensive for him to do further diagnostics. He didn't think it was too serious though! Being on a tight budget; like a lot of people these days; I took the car away.
Does anyone have any idea what it could be?
The car drives very well and doesn't smoke. The turbo seems to be working fine as well and there are no warning lights on.
Baffled

[toxicavenger]

could be your valves tapping but they do not knock. if you have a knocking sound I would think it is something else. so are you using some good oil?

[Jonboy123]

Hi Toxicavenger. Sorry for the late reply but i've been away and just got back. Yes, the oil is fully synthetic with a new filter. Its a sort of tapping noise which sounds like its coming from the top of the engine. I thought that it was a tappet but it sounds like just one of them. It does seem to quieten down under load but it is still there.

[19016c]

My car has been doing this again lately too. I think it is either a tie rod or a ball joint or some other suspension piece. For me it sounds like an uneven series of taps.

[MacNoob]

@jonboy
The serpentine belt tensioner and pulleys can make some noise that sounds like top end noise. Remove the belt and run the engine briefly to see if your noise is gone. You didn't waste money on the sump drop, that needed to be done for peace of mind anyways.

@19016c
Of course if your noise is suspension it won't happen with the car motionless...

[Jonboy123]

Thanks for that Macnoob. Your quite right, it isn't suspension but thanks for the advice though 19016c.
Where abouts is the serpentine belt?