Electrical gremlins

[E_T_V]

Usually I'm fairly handy when it comes to electrical things but this probmen has got me puzzled.

Last week when traveling home from work the car started fine but on the journey home (about 30 mins) the battery discharged and went flat. The charge light remained off when the engine was running and lit when it was stopped.

I was a bit puzzled but put it down to a 4 year old battery dieing in a spectacular fashion. So I replaced it with a new one borrowed from another vehicle.

I measured the voltage with the engine off to be 13.4 volts and with it running and no electrical load to be around 14v. This dipped to around 12.5v when the headlamps were switched on. The charge light remaining off at all times

Everything was fine monday and tuesday. I was away on busniess so my car was left standing until friday night. It started fine however on the way home again my battery died again.

My thoughts were that an alternator either worked or it didn't? But this one seems to be in between, or I have a major electrical short somewhere that isn't sufficient to blow the fuse. All ideas would be gratefully recieved. Is there a safe way to test the alternator output?

Also are alternators universal in the monty and maesty range? (as I've got a TD one I could swap it for) and can anyone recommend anyone to refurbish MY existing unit if it is duff (it isn't a standard alternator it is an uprated one used on police spec maestros)

[talkingcars]

I had similar with my maestro this week, swapped the alternator for the one off my monty (but they have the same engine)

James

[MGTurbo]

Alternator's can also die very slowly, i had a problem with mine last year which was similar, except my battery never died. At idle the voltage was just above 13 volts, as soon as any electrical load was placed on the charging circuit, this voltage would drop to about 12.5 with lights and heater on, but the battery never went dead?

The problem happened so gradually that i didnt notice anything untoward otherwise, at night time, it was possible to see the no charge light glow very lightly, more so when you turned the indicators on.

I then swopped the alternator for one from a scrapped Monty that was much newer, and at idle i had 14.4 volts, dropping to 13.5 under load. Problem resolved, as an added bonus the car was sharper and more responsive, it seemed the low voltage was affecting the ignition as well because after a run the exhaust manifold would gow red hot! It's been fine ever since, and we put it down to a failed diode within thwe alternator.

Gareth

[SimonR]

I would agree that it's an alternator problem. I had exactly the same thing last year with F153. The battery light was glowing very slightly during idle and remained on when I stopped the engine. A new one (£40) from PartCo (or was it Lucas?) solved the problem. Rover wanted about £80 for one so don't get it from there.

Just an aside the battry light still glows very little at idle, it's especially noticeable in the dark. It charges tho and the light goes out when I rev the engine.

[Simon]

That could be down to a slack alternator belt, try retightening but not too much as you will put a load on the beraings. Whwn an alternator light comes on when the engine is stopped, it usually means that it is back-feeding meaning that the rectifier pack has exceeded its useful life. The alternator will most probably be making a whining noise and will be very hot to the touch.

[E_T_V]

Thanks for the replies. It looks like my suspicions about the alternator were right then. However the charge light never glows under any circumstances even at idle. It doesn't whine or get unduely hot either. However what made me wonder was that a couple of days before the belt had started slipping. It was loose so I tightened it up and no more squeaking was heard.

Have any of the maestro range got the same alternator though? I've got a spare TD I can borrow one off to make sure that it is the problem before I splash the cash.

[H48HPE]

Ive just been looking into this and its a bit confusing, according to the rover manual there are 2 alternators for the petrol cars including 1.3, 1.6 & 2.0, and they are the Lucas A 127/55 and the lucas A127/65, these units have outputs of 55 and 65 amps at 6000 RPM/14V.

The haynes talks about a lucas A133 unit with a 55 Amp output for 1.3 and 1.6 engined early models, in the supplement it shows a different alternator which was fitted to later models but no part number is given. for the diesel engine they list the Lucas A127/65.

The EPC lists several different part numbers for alternators for the different cars across the engine range.

I would assume that a 55 amp alternator is good for a car with a 1.3 or 1.6 engine and a 65 Amp alternator is for cars with a 2.0 engine. however being me I would fit the 65amp unit across the board.

It would therefore seem that there are really 3 alternators that have been used the A133 which was probably replaced cos a better one came along in the form of the A127/55 which was uprated in later years to suit the big engines with the code A127/65.

Ive noticed on ebay that SMC listed a couple of MG 2.0 alternators on ebay but they said they were suitable only for the 2.0, the info above would suggest that this is wrong and I cant see why they would produce different alternator bodies, I would sugest that the bracketry is different and this would be swaped over from the old alternator anyway, the main alternator body being the same across the board.

the alternators fitted to some fords are the same as maestro ones, made by lucas with the same main body and they definitely can go on a maestro

Andy

[SimonR]

Andy, I to have been wondering about this. I think you're pretty much right although I've yet to prove either way EXCEPT that I bought a 1.3 altermator from Ledbury to put on F153 and the body was wrong - the adjustment lug was in the wrong place. Therefore the A-Series and S-Series alternators are different.

That probably doesn't help tho.

What may help Dan is that I now have a spare brand new Rover branded alternator spare....

SR.

[H48HPE]

Ive just been examining my spare one and comparing it to the pictures in various sources and you're correct, the castings are different, must be just the insides that are the same.

Andy

[Simon]

The basic rule of thumb is that you should always ask for an alternator to suit the engine type on a car, although there were 2 kinds of 2-litre alternators to confuse the issue- rear facing Early) and front facing (later).

[E_T_V]

As george is ex police he had the alternator uprated to a 65 amp one rather than the standard 55 amp one. As a stop gap I was going to replace it with a standard 55 amp item.

I took it all off today and had a good root around. According the the EPC the alternator from my scrap turbo diesel has the same part number so you think it would fit. Well I'm sure it would apart from it has screw type connections and mine has the plug type (which I don't really want to cut off). So I decided to leave that alternator where it was.

I had a minor mishap with my rover 214 alternator a couple of months ago and I still have what is left which looked visually identical, (apart from the casting was turned though 60 deg on one side which could be turned back easily enough. Anyway I removed the diode and brush unit from it and it fitted the suspect maestro one perfectly. I bunged it all back together along with a new fan belt and so far so good. So I'm off to buy a new diode unit for it as the 214's brushes are very badly worn.

The voltage now reads 14.2 no load and 13.5 full load, so hopefully that has cured that problem and I still have my more powerful alternator intact :D

[E_T_V]

Originally posted by F153JUE
What may help Dan is that I now have a spare brand new Rover branded alternator spare....

SR.

I don't suppose you could have a look at the part number for me could you as it may well be what I'm after..

Cheers

[SimonR]

Originally posted by E_T_V
I don't suppose you could have a look at the part number for me could you as it may well be what I'm after..

Cheers

Yeah, can do - it's at my Parents' place in their shed so I'll take a look when I'm next over there.

[Landcrab1800]

In my limited dealings with alts I have found that you can basically replace any lucas with another lucas as long as they are correctly handed (Left or Right).
To do this look from the back of the unit with the tensioning bolt downwards. On left hand alts the mounting lugs will be on the right and vice versa, this is of course in relation to N°1 cylinder.

I have even fitted an AC/Delco in place of a lucas. Packing was needed (on the mount bolts (washers))to alighn both alt and engine pulley.

Cheers