Hi, I've just inherited the wife's Skoda Felicia Estate off her, 1998 1.9 diesel (non-turbo), VW engine, Haynes manual reckons the engine type number is AEF. I always knew it could be a bit noisy but she never moaned about it so I ignored it, reliability was fine and mpg seemed OK (45mpg) and no MoT emission problems or anything.
Well I drove it for a 200 mile fast motorway round trip the other night and BLOODY HELL, my head was ringing afterwards like I'd spent all day in a foundry. Bloody, bloody noisy.
However, it doesn't do it all the time. Mostly it's just like your average diesel of that era. But if you put a fair amount of right-hand pedal down (and occasionally when you're not, just out of the blue), the engine will suddenly start hammering away like a bastard as if you've only just started it up on a cold winter morning. It doesn't start making the noise gradually - it suddenly switches from being OK to sounding like an end-of-life Ukranian tractor. Almost as if some valve somewhere has opened or the timing's changed slightly or something - a very definite step change in behaviour. No particular sign of any smoking when it's doing it.
Any suggestions? Is this a know problem with these engines, are they known to just be bloody noisy? Not what you'd expect from a VAG group engine that they put into the Polo of that era really, you would have thought. It's been regularly serviced, glowplugs are newish (shouldn't matter, obviously), only done 85k miles. Only other thing I can think of is that with a previous owner it was put into a garage for the engine 'surging' (?) and a sensor was changed, can't remember the details and too idle to go dig the paperwork out.