P38A Replacement alternator AMR2938

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JamesBB

JamesBB

Active Member
Posts
761
Location
Sandwich. Kent.
Hi Guys
I need to replace my alternator which is an original Magneto Marelli.
It's got a low output (not surprising being 24 years old) and I get a flat battery on regular occasions. The battery is also about 7 years old (non-brand name). I am aware of the battery drain issues, especially with the RF module, but even disconnected it loses charge.
I have also been having "Alternator Fault" appear regularly before starting the engine.

Can any of you recommend a good brand to replace it?
Denso is good but pricy.
WAI? Not really heard of before..........
Bearmach? The good bit here is I have a £60 voucher so get it half price.
Any others?

Is it just worth doing a rebuild of this one I have?

Thanks in advance.
James
 
How many miles? Worth inspecting first... Take it off and see how worn the slip ring is. If not too bad then for 20 quid you get a replacement VR with a 14.7V set point ( check, but i think you want Vr-F153a). This is better to charge modern batteries anyway, which need the higher voltage. Refit and see what voltage you are running now... worst case you may have to buy a replacement Alternator, but the new VR may still be worth transferring if the VR on the new alternator has a lower set point (and your new alternator were A127M)

Re battery - perceived wisdom is a hankook mf31 - but I have a Varta 069 (aka Bosch)
 
Last edited:
romanrob said:
How many miles? Worth inspecting first... Take it off and see how worn the slip ring is. If not too bad then for 20 quid you get a replacement VR with a 14.7V set point ( check, but i think you want Vr-F153a). This is better to charge modern batteries anyway, which need the higher voltage. Refit and see what voltage you are running now... worst case you may have to buy a replacement Alternator, but the new VR may still be worth transferring if the VR on the new alternator has a lower set point (and your new alternator were A127M)

Re battery - perceived wisdom is a hankook mf31 - but I have a Varta 069 (aka Bosch)
Click to expand...
Its got about 139,000 miles on it.
Voltage out last I checked was maybe 13 to 13.5v.Current alt says A127M.
 
Well with the message of "Alternator Fault" combined with quite high mileage and possible low voltage (its not here to double check) then it sounds like I am probably best advised to buy a new one.

Back to the original question. Can anybody recommend any particular make?
I can get the Bearmach at a good price, but do not know their quality. WAI, Bowers and RollcoI have not heard of before which makes me want to steer clear. Almost certainly all are made in China.
I just fitted a new Denso (which actually claims to be made in Japan) to my Jag and it's excellent in terms of build quality, it has to be said. At least fitting the P38 alternator is a really simple task in comparison.

I will take the plunge for one by the end of the week.
Cheers
 
I'd really be putting some effort into maintaining the Magneti Marelli one. My 98 RR is 140k too, although it's hard to know if it's the original alternator or not, perhaps it got replaced/ remanufactured at some point., but I just changed the VR. My 98 V8 Defender definitely uses the original and is still going strong, I just changed the VR for the better set point. They're both 127M alternators, one 100A and the other 120A, and both took the same Vr-F153a https://www.mobiletron.co.uk/MobCAT

Buy new if you want but more than likely you'll spend a few hundred quid extra, to get the performance you could have had for 20 and knowing you have the guts of your alternator were built before the chinese got in on the act.
 
Price is decent - the only thing i never worked out was - if you buy a new replacement, and especially if you buy Genuine, are you getting a 14.7V set point - or the original (genuine) spec of 13.8V? 13.8 will kill your new battery soon enough. So I would also budget the £20 for a new VR in case your replacement fails to get over 14V
 
I have just seen the other replies about maintaining the original. It certainly makes sense, cheaper and maintains the higher quality part. Looked a the link but they do not seem to have the VR when searching by vehicle. Will spend more time looking........
 
romanrob said:
It has brushes...looking at the picture of the new one you slide up the round back plastic cap and they'll pop out.
Click to expand...
Excellent, yes David from Mid-Ulster Rotating Electrics Ltd has just confirmed that too.

A new one ordered. Thanks for your help with that.
Cheers
 
no probs. the screws to remove the VR are small and irregular hex head, take your time... It's possible to do on the car (if you can get the cage past the redundant bracket on the fuel rail - I cut the bracket off), and using a little mirror, but you may find it easier to remove the alternator and do it on the bench
 
Grrrrrr said:
Personally I didn't muck about and took the alternator off. Especially if it is your first time it is a lot easier.
Click to expand...
That is what I am going to do. It's an easy job to take it off compared to what I just went through on my Jag. At least I can remain standing. :)
 
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