Has anyone replaced the alternator on a 5.0 S/C and if so, do you access/remove from the bottom or need to go in via the top?

I sadly broke down on the M3 late last night with the family onboard and had to get recovered home for the first time in my life. First the radar cruise went offline, then 10 mins later the Adaptive Dynamics, then 10 mins later a flurry of other random things and finally a Charge failure warning popped up. Thankfully the truck never cut out and I safely got off the motorway and stopped.

Having had a play with my IID tool this morning, the (fairly new) battery seems absolutely fine, but taking it for a drive the alternator seems to regularly cut out and not produce any charge, so I'm assuming at ~14 years old it's kaput.

I bought a new Denso replacement for a great price on a special Ebay offer this morning, but debating if I fit myself given very limited time with 2 small children or just take it to the local garage!

Thanks,

Paul

Click image to enlarge

Sorry to hear of your issue,

On the 5.0 supercharged L405 it can be changed from underneath, I am sure someone will advise on L322, I would assume same procedure.

Amazing, thank you so much!

I took the front trays off this evening and it looks like it should come out there if I disconnect the earth lead to make a suitable gap, just first need to take the wheel off and part of the wing access panels too I think to get enough access to manoeuvre.

Will have another look later in the week when I'm back at home!

Nearly 6 weeks later thanks to manic work and 2 small children meaning I rarely get any large blocks of time to play mechanics, and the L322 is back on the road with a shiny new Denso alternator. A right pain to get the old one off and out through a very small gap and the new one back in, but as usual having done it once and learned all the below tricks I'm sure next time it would take a fraction of the hours!

Total cost was about £160 - I managed to get a brand new OEM Denso unit off Ebay during a discount window for £140 instead of the more usual £180-200, and spent £10-15 on a couple of cranked 13mm spanners to help access some tough mounting bolts.

For reference given I couldn't find many articles/notes/videos on doing an L322 5.0 S/C alternator:

1.) It really will come out the bottom, despite the hole not being much larger than the alternator.
2.) Need to remove front right wheel and the lower plastic wheel arch covers and the front under tray. I didn't remove the full wheel arch liner.
3.) I removed the idler pulley for the aux belt to give more hand space around the alternator and to get to the front mounting bolt, which made life much easier
4.) I released tension on the main/supercharger belt too so the tensioner moved outwards, making a larger gap for the alternator to come out/go back in
5.) Completely removed engine earth strap, as both ends were in the way
6.) Removed right hand air box/filter assembly so I had some space and visibility from the top too
7.) The harness/plug connection to the alternator comes out (and is refitted) with the alternator slightly forward, the main power wire you can easily access when fully mounted
8.) Test fit the new alternator before you start connecting any wires - it does take a little while to work out how to get it back in through the small hole and rotate into the correct position

All fairly straightforward, but heaving around underneath on your back with a 10kg alternator in the fingertips was fun!

Afternoon Paulbrown22

Glad you managed to get her all sorted.

I imagine good to have her back on the road again


Dr F

Thanks, definitely happy to have it back on the road again - I hate cars that aren't 100%!

We are lucky in that we have other cars and generally only use the L322 for longer journeys with the whole family - for anything locally we mostly use wife's car or I take one of the classics if just me! So I was in no massive rush to get it fixed, but very happy now to know it's all sorted hopefully this alternator lasts the next 14 years .

While the under trays are still off just going to do some proactive protective work underneath, and then remount the final plastic parts.