33 replies to this topic

[lsto]

Thanks for the replies guys. Not had a chance to look at this as family is down with a bug again including me.
Is the regulator being easy to change also the case on MPI minis as it seems is quite different to previous ones from a quick look?

When i test the voltage at the alternator it kind of flickers around, have seen 14ish a cpuple of times but mostly its less than 1v.
The light goes totally off as you'd expect when all working fine and the volt gauge reads around 13V when lights etc off and drops to mid 12s when lights and heate are on

As a lot of the replies above I'd check the connections at the alternator, starter and battery, including earths are in good condition and not corroded. Ideally you want about 14 to high 13v at the battery with the engine running. If your getting this then turn on all your loads, and check again at the battery, you still want 13+ volts. If your only getting mid 12s when your loads are on and all your connections are good I would suggest your alternator is on its way out. In the cold battery's take a hammering and a weak charge will slowly kill the battery.
Good luck.

[john2502]

Hi all, so had 20mins to look on lunch break today, i've given the connections at the alternator a good clean which they did need to be honest. Tried and still similar (13.1V at battery when idle, 12.7 when lights on). Alternator is tricky to get a reading off but i couldnt get over 12ish coming from that no matter what i did.

 

Can i ask a very basic question, where is the earth strap pon my MPI mini, i can't see where it would be. I have attached a picture of the engine bay. I am suspecting earth strap or the alternator currently.

 

Haven't had the chanve yet to run more tests such as voltage drop, why is life so busy sometimes.

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[coopertaz]

not 100% for mpi, someone will correct me if incorrect, but attached to steady bar and bulkhead just below air inlet and behind breather canister. but problems here normally manifest as poor starting

[john2502]

Thanks, think i might have found a culprit. See picture of the earth strap, doesn't look too healthy. Hard to get a picture where it is but you can kinda see here.

 

Am seeing people have also been running a second one, just thinking at least for now as this is a bit tricky to get to so order 2 and run a more accessible one at least for now. Alternator to slam panel seems to be an option some have used?

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[coopertaz]

they uausally corrode like this, if you have jump leads make a temporary negative using these from engine block to chassis (head stud to ecu mounting bolt easily accesible) but brush first to get clean contact then check alternator output again at alt. and battery. still think more likely with low output at alternator, you're looking at reg/brush unit on it. easy to get to on mpi and cheaper than new alternator, but only held by 2 small bolts so care must be taken not to shear them.

you mention RAC changed battery did they not do charge rate checks on battery after renewing it?

Edited by coopertaz, 29 January 2024 - 12:59 PM.

[bpirie1000]

Just b9ot another one on.,so long as it is on the block and on a good body earth it will be fine..

Even try a jump lead in the meantime.. engine block to body earth.. see what voltage does..

Mpi engine earth starts are a pain to get to..couple of hours worth.....

[coopertaz]

put second on my cars from master cylinder mount to breather bolt, just thought jump lead for tester you dont need to crimp up a lead

[john2502]

So have ordered 2 earth straps from minispares as i think best to replace that either way plus run a potential second.

 

Tried with a jump lead from engine stud to ECU mounting bolt and even tried a few other places, the gauge in the car still stays at 13.1V when idling which is what it's showing at the battery (so that is accurate). I've got my suspicions the battery is now past it as even when charging with my mains halfords charger on fast charge it barely reaches 13V (doing this now as need the car tomorrow so every little helps).

 

Few months ago when the last battery died the RAC guy said that there was a larger than expected battery drain (i wrote this off as the usual Rover alarm system doing it's thing, think he said 0.3Amps but not sure now), the battery was dead and that he was only getting 13.3V when idling. He suggested maybe the alternator belt was a bit loose but i've checked this and seems within tolerance.

 

Once started i drove down to the motor factors with RAC van following me and got a new Napa battery under warranty as the current one was less than a year old which i fitted in the car park and all good, charging at above 14 again. This has then been fine until a few weeks ago when it started to be very sluggish starting again.

 

Am still not 100% sure the alternator or battery are good to be honest, especially because using the jump leads as a temp earth was not sucessful. I kind of want to try a fresh battery but not sure how many times I can get another under warranty without them thinking that my car must have an issue killing them or something, haha.

[john2502]

Forgot to put, thanks for your help on this chaps, and for bearing with me!

[bpirie1000]

Try joining the two jump,leads together and go from battery -ve and then link the two cables together... then onto the block...

In essence a straight raw negative....

See what happens with that.. also would suggest examining the main power cable insulation condition. May need a ramp for that but have seen these chaff at the front subframe, get damaged wit the retainer chanel bottoming out on the ground or melt on exhaust...

Keep going running out of things it could actually be now...

Also would say RAC do not give a great service if you are still chasing the same fault...

Keep smiling....

[Spider]

Sorry, I don't know if this was covered, but I read in your opening post you felt that the drive belt might be a bit loose.

It is manually adjusted. This might help ?

 

[john2502]

Ah yes good idea! Will give that a try tomorrow and see how i get on.

Yeah the RAC just want to get you going again and get you out of their hair most of the time. Fair enough as that is their job really. Haha.

I cant figure out why rover would use a braided earth cable rather than insulated as per the battery cables etc. Seems odd to me but maybe there was a reason.

[lsto]

If I was in your position I would replace the alternator, if your still only getting 13.1v with an extra earth then you have eliminated a poor earth connection. The battery has already been changed and you still have the same fault so I doubt its another duff unit.
You need a good 14.2v to maintain the battery, this time of year the electrical system has to work hard so faults always show themselves in the cold.
Fault diagnosis is fun, good luck.

[john2502]

Thanks spider. Looks like it can be manually adjusted on MPIs but having now had a look at it i think its tight enough. Think i read 6-8mm deflection and its within that.

Good fun eh.

If i didnt use the car as a daily i could start taking things apart with more confidence it wouldnt affect things but i kinda need it for getting to work and the kids to school/nursery!

[john2502]

Thanks Itso. Yeah i know what youre saying. It does seem unlikely another battery has failed (3rd in just over a year).

My only suspicion on the battery come from the voltage isnt super high when charging it from the mains with my charger. Im guessing it should charge at about 14V from mains and only gets about 13V (so similar to alternator at idle).
Its a puzzling one for sure.
Seems an odd coincidence the earth cable is knackered AND alternator/battery (3rd one) too.
Battery is easiest to replace so am considering trying a new one to at least rule that out....hmmm