406 HDi loud rattle/clicking on cold start

[praxibetel]

Hi all, sorry to make another thread about my 406 so soon but whenever I start cold, or after the engine has cooled for a while, I get a loud metallic rattle/clicking noise from the belts side of the engine, and and also a slight rumble at first which is less pronounced.

Initially I thought it was the crankshaft pulley so I changed it, along with the drivebelt and tensioner for good measure, but the noise is still there on startup. It's difficult to pin down exactly where it's coming from but it sounded similar to my old 206's crankshaft pulley which I changed after it got noisy.

The noise goes away after about 10 minutes of driving, but up until that point it sounds rather clicky at low revs.

[spider]

It could be the tensioner spring.

I'd suggest removing the drive belt and running the engine without it just for a few seconds to determine if the noise is related to an ancillary or more deep seated.

[praxibetel]

I was thinking I'd try that to be honest. I replaced the tensioner when I did the crankshaft pulley and the noise didn't change.

[spider]

It can be difficult to pin point the noise I know.

Its worth doing this quick check to be sure. This way you also cover things like rattling alternator bearings / power steering pumps etc and the like too, so a 'no belt' test you can then be sure its 'internal' as such.

It may be worth pulling the top cover of the timing belt (if you can) as well just to see if that appears OK. I mean something may be catching it (unlikely but not impossible)

Random sidenote, I know this is stating the obvious but don't remove the crank pulley and run the engine without it ( ! ) as the timing belt is very good at finding this out and loves to make a run (no pun intended) for it... Its been done ( ! )

I'd just whip the ancillary belt off, run the engine to determine for sure if its internal or external.

[white exec]

Rumble/rattle/clinking sounds just like a DMF on the way out. Do you have one of these on that engine?

[jsp]

Or an altenator clutch pulley common failure

[praxibetel]

Pretty sure it's not the DMF as it's already been done on this car. I won't be running the engine without a crank pulley so no worries there I'm helping a friend with his nissan on Sunday morning so I'll take the belt off and see what it sounds like then.

It does sound like it could be coming from the alternator/PAS pump area. Just hoping it's not something more serious. Thanks everyone for your advice I'll post back when I've eliminated anything driven off the aux belt.

[praxibetel]

Okay so I finally got round to taking off the belt and running the engine. First thing I noticed is the alternator pulley has a bit of a squeak when turned by hand, and the noise is indeed completely gone when the engine is running without the belt. I was thinking of just replacing the alternator with a used ebay unit, just to get it done.

Side note, the manual tensioner/idler pulley seems to be made of cheese and the two points for adding tension are starting to round out, so I should probably replace that too, or at least have a spare handy...

Thanks for all your suggestions guys!