I have a '93 Citroen ZX Avantage Auto 1.9D (non-Turbo) about a year ago I got a strange whine whilst on the motorway, I pulled over and it never did it again until now.
Essentially if you're accelerating, or you remove your foot from the accelerator everything sounds fine. But if you're driving on the level and only lightly pressing the accelerator there is a terrible whining noise. Unfortunately it's one of those noises that is difficult to pinpoint exactly where it is coming from.
Interestingly it doesn't do it when cold, it takes a few minutes driving before the whine kicks in. I once got rid of it for a few hours after I went through the car wash, it also seems to get better in wet conditions (a lubrication issue somewhere perhaps?) although it doesn't go away entirely.
I initially thought it was a slipping belt as this sometimes squeaked when using the power steering heavily, but having tightened the auxiliary belt it's made no difference to the noise (other than I no longer get a screech when the steering is at full lock). The timing belt is toothed so there appears to be little likelihood of this slipping...
Anyone shed any light on this?
Regards, Jason.