406oc.co.uk

Can anyone offer any advice on my wife's beloved 406 HDi please? There is a loud whining noise that appears to be coming from the alternator. It is quite noticeable when idling or driving and doesn't get any better or worse when the engine is warmed up. The noise doesn't really seem to change when I switch on the A/C or heavy electrical loads either. The car is a 2003 model with only 38K miles so I'd be surprised if the alternator bearings are the real problem. The alternator is the Bosch 150A version and is quite expensive (even from GSF, LSUK etc.) so I don't want to replace it on a whim. I may be able to take the car off the road for a full day in a few weeks time and this would allow me to remove the alternator and take it to be "rebuilt" by a local auto electrician. I guess that would be the lowest cost way of troubleshooting the problem.

As a test, I used a long screwdriver as a "stethoscope" and the noise is definitely loudest on the alternator (quite a loud buzzing can be heard which doesn't sound normal). I asked a friendly Peugeot technician about it (he was on his smoking break) it and he mentioned to me that the noise may actually be from somewhere else and is just being transmitted through to the alternator via the mountings. He said it may be worth changing the auxiliary drivebelt tensioner pulleys, but I didn't have the car with me for him to see so he couldn't be too sure.

I removed the auxiliary drive belt today and checked the A/C pulley, upper and lower tensioner pulley, and power steering pump pulley for any roughness by hand. They all seemed OK - there was a very slight roughness from the alternator pulley but nothing obviously wrong. I realise things may be different when there is some tension load on them, but I thought it would be worth a try in case something was very rough. The crankshaft pulley is also OK at the moment - no sign of it breaking up yet.

Could the noise actually be coming from something on the timing belt instead? I understand that you can't run the engine with the auxiliary drive belt removed. Is this something to do with the notorious two-piece crankshaft pulley?

What do you folks recommend? Should I go with my instinct and have the alternator rebuilt, or should I first try replacing the tensioner pulleys?

Cheers,

Savvy

possibly two things, the crankshaft pulley, although common it doesnt give these symptoms, more likely its the auxilarly belt tensioner, changing this with the belt is the cheapest option

Thanks Jameslxtd

The dealer price for the tensioner parts is outrageous so I'll maybe try and get a Gates micro-V belt kit complete with the tensioner pulleys from a motor factor. I notice there is a guy on ebay selling them as well. Interestingly, the dealer did confirm that the crankshaft pulley has now been changed to a solid one-piece design due to all the failures they have had - logically I should really change it at the same time as the new (solid) one ought to last the life of the car, but that's another £120.

Savvy