Orgasmic Farmer Posted August 20, 2012 Share Posted August 20, 2012 Bit of history.... I acquired a newish 120amp Denso alternator for my old 300 tdi Disco which was on the truck for about a year or so with no issues. This then became the donor for my 110 which meant the engine wasn't really used for 12 months other than being started a couple of times. I also gave it a damn good clean with the pressure washer when it came out of the Disco. Now the 110 is up and running and finally on the road I thought all was OK. However, on its' first proper run out as soon as I got above 60mph on the motorway the charge light started flickering ever so slightly. The faster i went the more it shone. As the trip progressed it came on more solidly (though always with a flicker) even at lower speeds. After standing for a while I did a few short local trips and it didn't come on again but as soon as I got back on the motorway to come home it was the same as ever. I have a volt meter which seems to confirm that when the light is on there is no charge since it rises and falls in a consistent manner. So does anyone have any suggestions. Might it just be rusty contacts? Is it possible to service/clean the inside of a Denso alternator? One thing i noticed when I attempted to remove the plastic cover from the back was that the inner nut on the main output post appeared to be loose (it seems to hold a thick collar/spacer beneath it). Could this have anything to do with it (it may have been disturbed when changing the wiring looms over??) Thanks for any advice Mark Quote Link to comment Share on other sites More sharing options...
TSD Posted August 20, 2012 Share Posted August 20, 2012 Sounds like sticking brushes to me. I've swapped the brush assembly on a Denso in the past, but only once and I don't remember the exact details. I'd strip it until I could get to the brushes, clean it out as best a possible, excercise them in and out and add WD or some other solvent/oil combo - you aren't trying to lubricate them as such, just using the fluid to carry off crud from the brush housing and brushes. Quote Link to comment Share on other sites More sharing options...
vulcan bomber Posted August 20, 2012 Share Posted August 20, 2012 As said, sounds like an issue with the brushes. The copper contact rings would probably benifit from a clean up on a lathe but I doubt its that critical. Quote Link to comment Share on other sites More sharing options...
Orgasmic Farmer Posted August 20, 2012 Author Share Posted August 20, 2012 Have just cleaned brushes and slip rings and reassembled. Now need to get her up to speed for a test.... Bed first Quote Link to comment Share on other sites More sharing options...
Pastycrimper Posted August 22, 2012 Share Posted August 22, 2012 I know for the original Lucas (then Marelli) A127 (65A) alternator you can get full refitb kits. Given that Denso now make these (i.e the 65A version). I wonder if the kit will work on the 120A version? It contains new brushes, voltage regulator and diode (rectifier) pack as well as bearings....see http://www.ebay.co.uk/itm/ALTERNATOR-REPAIR-KIT-FOR-A127-LUCAS-MARELLI-PRESTOLITE-MARINE-LANDROVER-FORD-/230733271190?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item35b8c65096 Maybe when you serviced yours you will recognise of the parts are the same. It may well be that the Denso ones have a slightly different internal construction so I can not say whether this service kit will work. Quote Link to comment Share on other sites More sharing options...
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