240 Alternator making an absolute racket

Was on my way home and suddenly out of the blue the car starts making the noise below, really, really loud. Pulled off belt by belt and narrowed it down to water pump, fan or alternator as it stopped when I pulled their belt.. Changed the waterpump because I could feel a bit of play in it. Still makea da sound. So started the car with just the fan detached (belts still on) sound still there. Now onto changing the alternator I suppose?
I did test it for play in the little fan on it and it felt tight, does anyone have any idea what it could be exactly? I blew a fuse a few days before which is a rarity, could this be at all related? Maybe damaged some wiring when I did engine mounts last week..https://youtu.be/hE7VQuzsKSo


  • jamesincJames (@jamesinc) Oz Volvo Ice Fortress
    edited May 2018
    Sounds a bit like a shot bearing. If you're certain it's the alternator, you can actually rebuild the alternator with new bearings. Depends which alt you have, but there might be kits available.

    You could always tear down the alt, measure the bearings (or just read the SKUs) and order bearings to suit, but obviously you'd have to lay up the car for a few days that way.

    PS when installing bearings, don't be that guy, put the SKUs facing outwards so they can be read without having to pull everything apart!
  • DauntlessDauntless (@Dauntless) Central West NSW
    How does the alternator feel/sound when turning it by hand? Does it have play?

    Assuming it's a standard 55A Bosch alternator? You can upgrade them with the guts from a Magna? 85A alternator, or just throw on a 100A Denso 940 alternator.
  • @jamesinc if I had the time I'd love to pull it apart but I have a bloke looking at it tomorrow to buy and would like to have it running for him. I will hold onto it though as it still works and doesn't look that old so a rebuild could be worth it.

    @Dauntless tbh it doesn't feel loose, but after the tests I've done there's nothing else it could be, I also had a look at some clips online of rooted alternators and the sound is the same. Shaun on here has hooked me up with a spare, he has a few in his garage of goodies. Hoping they didnt vary throughout 240 years and between LH and Kjet
  • DauntlessDauntless (@Dauntless) Central West NSW
    From memory yours will be a 55A, and later ones (86+ maybe?) went to 80A. I think they're a straight swap, but I've never tried.
  • From memory yours will be a 55A, and later ones (86+ maybe?) went to 80A. I think they're a straight swap, but I've never tried.

    lets hope so, thanks for the input mate. I'll report back
  • On swapping out the alternator I noticed the tentioning bracket was loose where it connects to the block, possible it was rubbing on the back of the crank pulley. Feeling fooooolish for not spotting this sooner. But then again if it was touching wouldn't it have still made the noise when the alt belt was off, unless it was the belt pulling it in contact with the pulley. Mmmmmm

  • False alarm, tried it with old alternator on and pulley clearing bracket and it's still ear torturous
  • New alternator didn't fix the problem either. What am I missing ffs
  • How is the steering? could it be the power steering pump?
  • How is the steering? could it be the power steering pump?

    The noise persists when I remove the PS belt. The only time it has stopped was when I started it without the belt driving the waterpump and alternator
  • jamesincJames (@jamesinc) Oz Volvo Ice Fortress
    I mean it's either the alternator or water pump right? Did you put the replacement alternator on?
  • I mean it's either the alternator or water pump right? Did you put the replacement alternator on?

    yeah i put it on last night to no avail. was working my way around with a screwdriver to my ear with the car running trying to find the source but no luck. something somewhere is making contact with something it shouldn't be
  • Harmonic balancer?
  • DauntlessDauntless (@Dauntless) Central West NSW
    edited May 2018
    If the balancer is a 2 piece, they can fail and slip back towards the engine. On my 740 it chewed through the timing cover.
  • OK, long shot but could it somehow be the thermostat has broken and is rattling around in the housing only when it's getting flow from the water pump? Very odd! Also, does it happen with only a single belt on the alternator or only with both belts on the alternator? I assume you tried with only 1 belt to rule out some funky mismatch in length between the dual belts?
  • Last night while it was running I was pressing the timing cover seeing if the sound changed as it gained more clearance from the balancer, nothing noticeable.

    @carnut222 the thermostat is fine and after you mentioned it I tested it with one of the belts removed and it still bloody did it!

    Again thanks for the suggestions everyone, I'll get there eventually!
  • 1971_144GL1971_144GL (@1971_144GL) Launceston, Tasmania
    How old is the timing belt tensioner bearing? They sound like you describe when they fail. It would probably feel notchy if it is making that much noise.
  • How old is the timing belt tensioner bearing?

    I'm not sure tbh, I dont think I changed it when I did the timing belt last year. Would I be able to feel it with the belt still on?

    Keeping in mind this sound had never happened before and arrived in an instant
  • edited May 2018
    Starting to worry it's a bottom end bearing, just put the screwdriver/stethoscope to the sump pan while engine running and could hear some nasty sounds with my untrained ear
  • edited May 2018
    But then I'm puzzled as to why the sound stops when I remove the alt and wp belts. Could removing them give enough relief to the crankshaft bearing to stop it from squealing..
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