Tacho is certainly suspect!
Discussion
12.7v is not charging so each time you start the car the battery is draining further. If the battery is good it will recover overnight so long as the voltage does not get too low. Nominal battery voltage is 12.6v on a good battery - 2.1v per cell x 6.
Best to disconnect it altogether as QBee says, as alternators are prone to discharging batteries if the regulator has failed. The ignition warning LED not working means there is a break within the alternator regulator.
The comment above about disconnecting the wire was to see if this made a difference to the tacho reading, not the alternator.
For peace of mind I would be fitting a good quality one - fit and forget.
Best to disconnect it altogether as QBee says, as alternators are prone to discharging batteries if the regulator has failed. The ignition warning LED not working means there is a break within the alternator regulator.
The comment above about disconnecting the wire was to see if this made a difference to the tacho reading, not the alternator.
For peace of mind I would be fitting a good quality one - fit and forget.
Edited by N7GTX on Sunday 22 April 11:11
I am as certain as can be that your Alternator has a faulty rectifier, the field diodes will have gone short circuit and when that happens they put a permanent supply onto the rotor which will overheat more so when stood still
When the field diodes go short circuit there is a voltage being applied to the alternator warning light cable all the time rather than when the alternator is turning, when there is a voltage at the warning light terminal there may be some dash lights that are being extinguished by that voltage, those warning lights that may be being extinguished are the same ones that are normally extinguished when the alternator is turning and charging
When the field diodes go short circuit there is a voltage being applied to the alternator warning light cable all the time rather than when the alternator is turning, when there is a voltage at the warning light terminal there may be some dash lights that are being extinguished by that voltage, those warning lights that may be being extinguished are the same ones that are normally extinguished when the alternator is turning and charging
Well Anthony have disconnected battery again to be on the safe side and it's not as if am without a car after all just annoying however it is proof that cars don't like not being used. I think if this had been used more in the past the bearings would not have dried up then failed.
From my web searches it seems that this alternator was also used on some Massey Ferguson's and Fords as well and Land Rover's. Hopefully once replaced/repaired things will be better with a fully operational charging system once again.
From my web searches it seems that this alternator was also used on some Massey Ferguson's and Fords as well and Land Rover's. Hopefully once replaced/repaired things will be better with a fully operational charging system once again.
N7GTX said:
12.7v is not charging so each time you start the car the battery is draining further. If the battery is good it will recover overnight so long as the voltage does not get too low. Nominal battery voltage is 12.6v on a good battery - 2.1v per cell x 6.
Best to disconnect it altogether as QBee says, as alternators are prone to discharging batteries if the regulator has failed. The ignition warning LED not working means there is a break within the alternator regulator.
The comment above about disconnecting the wire was to see if this made a difference to the tacho reading, not the alternator.
For peace of mind I would be fitting a good quality one - fit and forget.
I am as certain as can be that your Alternator has a faulty rectifier, the field diodes will have gone short circuit and when that happens they put a permanent supply onto the rotor which will overheat more so when stood still
When the field diodes go short circuit there is a voltage being applied to the alternator warning light cable all the time rather than when the alternator is turning, when there is a voltage at the warning light terminal there may be some dash lights that are being extinguished by that voltage, those warning lights that may be being extinguished are the same ones that are normally extinguished when the alternator is turning and charging
Thank you both your comments have been noted. It is odd how this all seems to happened at once:-Best to disconnect it altogether as QBee says, as alternators are prone to discharging batteries if the regulator has failed. The ignition warning LED not working means there is a break within the alternator regulator.
The comment above about disconnecting the wire was to see if this made a difference to the tacho reading, not the alternator.
For peace of mind I would be fitting a good quality one - fit and forget.
Edited by N7GTX on Sunday 22 April 11:11
I am as certain as can be that your Alternator has a faulty rectifier, the field diodes will have gone short circuit and when that happens they put a permanent supply onto the rotor which will overheat more so when stood still
When the field diodes go short circuit there is a voltage being applied to the alternator warning light cable all the time rather than when the alternator is turning, when there is a voltage at the warning light terminal there may be some dash lights that are being extinguished by that voltage, those warning lights that may be being extinguished are the same ones that are normally extinguished when the alternator is turning and charging
Noisey bearings
Regulator
Probably diode .................................. all failing at the same time. Nearly 25 years is quite good but when one considers the low miles it is not so good really. We will know more tomorrow with any luck and am really wondering if new clean connections along with proper charging may indeed help the tacho issue.
Might be time to change the headlight bulbs to the new Osram Nightbreakers I bought last week locally.
Could either Penelope or one of the other recent knowledgable posters comment on whether a failing alternator could have given the tacho issue?
I had a battery drain recently......it so I thought......but a new battery showed that trying to find the drain before changing the battery would have been an utter waste of time.
I had a battery drain recently......it so I thought......but a new battery showed that trying to find the drain before changing the battery would have been an utter waste of time.
QBee said:
Could either Penelope or one of the other recent knowledgable posters comment on whether a failing alternator could have given the tacho issue?
I had a battery drain recently......it so I thought......but a new battery showed that trying to find the drain before changing the battery would have been an utter waste of time.
Rev counters on many cars are connected to a terminal on the alternator, marked P, S (Ford), T or W. Many older cars take their supply from the coil but yours is an aftermarket ecu now and your coil is also replaced with coil packs? Sorry, I don't know the answer on your car but probably the ecu or the alternator. See if you can identfy the W (or P or T) terminal and if there is a wire connected that goes into the loom then that will be it.I had a battery drain recently......it so I thought......but a new battery showed that trying to find the drain before changing the battery would have been an utter waste of time.
If the tacho is connected to the alternator then a failing alternator could cause the issue and a big battery drain (overnight discharge).
N7GTX said:
QBee said:
Could either Penelope or one of the other recent knowledgable posters comment on whether a failing alternator could have given the tacho issue?
I had a battery drain recently......it so I thought......but a new battery showed that trying to find the drain before changing the battery would have been an utter waste of time.
Rev counters on many cars are connected to a terminal on the alternator, marked P, S (Ford), T or W. Many older cars take their supply from the coil but yours is an aftermarket ecu now and your coil is also replaced with coil packs? Sorry, I don't know the answer on your car but probably the ecu or the alternator. See if you can identfy the W (or P or T) terminal and if there is a wire connected that goes into the loom then that will be it.I had a battery drain recently......it so I thought......but a new battery showed that trying to find the drain before changing the battery would have been an utter waste of time.
If the tacho is connected to the alternator then a failing alternator could cause the issue and a big battery drain (overnight discharge).
I was referring to the OP's issues on his newly acquired 1993 Chim. Before he continues looking at the lazy tacho and the alternator issue as separate issues, does anyone who knows about these things know whether the tacho issue is in fact being caused by the failing alternator?
QBee said:
Could either Penelope or one of the other recent knowledgable posters comment on whether a failing alternator could have given the tacho issue?
I had a battery drain recently......it so I thought......but a new battery showed that trying to find the drain before changing the battery would have been an utter waste of time.
I had a battery drain recently......it so I thought......but a new battery showed that trying to find the drain before changing the battery would have been an utter waste of time.
The above image that Brithunter has posted doesn't show a cable connected to the W Tachometer terminal (See top left stud terminal) obviously this means his tachometer is ECU or Coil Pulse driven.
Nothing surprises me anymore ever since witnessing an engine not starting due to a starter motors interference with the vehicles ignition system, there must be a possibility that a bad alternator could affect the tachometer signal but I would expect it to also affect the ignition system at the same time but stranger things have happened
It will be interesting to read up on Brithunter's later findings
Editing this to add something that's just crossed my mind - A faulty alternator due to short circuit field diodes plus possible regulator, main diodes and stator winding problems due to the overheating could possibly be supplying an incorrect voltage or type of voltage (bearing in mind an alternator produces AC voltage) through the brown/yellow alternator warning light cable to the instrument cluster and that could very easily play games with the Tachometer and other components
Edited by Penelope Stopit on Sunday 22 April 16:01
Penelope Stopit said:
I'm excited about what the final findings or fixes are
I know 
Great fun these car problems when it’s not your car especially if you can help out
I’d say 25 years and only being used during summer months is a good working life overall.
It’s the bearing that’s failed and had a knock on effect to the workings afterall.
Classic Chim said:
Penelope Stopit said:
I'm excited about what the final findings or fixes are
I know Great fun these car problems when it’s not your car especially if you can help out
I’d say 25 years and only being used during summer months is a good working life overall.
It’s the bearing that’s failed and had a knock on effect to the workings afterall.
What do you know about grease, I know nothing about grease and was wondering how much better todays grease is compared to the 25 years old grease in this alternators bearings, the 25 years old grease has surely dried out and hardened, would a modern day grease still be ok in 25 years time
Only a thought but....
Penelope Stopit said:
Yes it is good fun
What do you know about grease, I know nothing about grease and was wondering how much better todays grease is compared to the 25 years old grease in this alternators bearings, the 25 years old grease has surely dried out and hardened, would a modern day grease still be ok in 25 years time
Only a thought but....
I wouldn’t bet much on it! What do you know about grease, I know nothing about grease and was wondering how much better todays grease is compared to the 25 years old grease in this alternators bearings, the 25 years old grease has surely dried out and hardened, would a modern day grease still be ok in 25 years time
Only a thought but....
Dried out grease, the more you use them the less atmospherics effect the grease in these things so more use surely it would have worked for even longer.
For a car that stood and has been rebuilt too to take on the huge journey and get there in one piece is a miracle.
Would an MGB that's been stood about do that, he’d still be travelling so we’d not know yet
I love MG by the way
Classic Chim said:
Penelope Stopit said:
Yes it is good fun
What do you know about grease, I know nothing about grease and was wondering how much better todays grease is compared to the 25 years old grease in this alternators bearings, the 25 years old grease has surely dried out and hardened, would a modern day grease still be ok in 25 years time
Only a thought but....
I wouldn’t bet much on it! What do you know about grease, I know nothing about grease and was wondering how much better todays grease is compared to the 25 years old grease in this alternators bearings, the 25 years old grease has surely dried out and hardened, would a modern day grease still be ok in 25 years time
Only a thought but....
Dried out grease, the more you use them the less atmospherics effect the grease in these things so more use surely it would have worked for even longer.
For a car that stood and has been rebuilt too to take on the huge journey and get there in one piece is a miracle.
Would an MGB that's been stood about do that, he’d still be travelling so we’d not know yet
I love MG by the way
An MGB stuck in overdrive because the overdrive solenoids grease had dried out wouldn't complete the journey in any hurry, have just read that it is important not to select reverse on an MGB if it's stuck in overdrive
It takes a brave person to do a long journey in an unproven car, well done to Brithunter
Penelope Stopit said:
That's interesting, I didn't know about grease and usage
An MGB stuck in overdrive because the overdrive solenoids grease had dried out wouldn't complete the journey in any hurry, have just read that it is important not to select reverse on an MGB if it's stuck in overdrive
It takes a brave person to do a long journey in an unproven car, well done to Brithunter
Yes I agree. Brave indeed. An MGB stuck in overdrive because the overdrive solenoids grease had dried out wouldn't complete the journey in any hurry, have just read that it is important not to select reverse on an MGB if it's stuck in overdrive
It takes a brave person to do a long journey in an unproven car, well done to Brithunter
Hopefully he’s getting over the shock.
Driving one of these for an afternoon will knock most people about let alone with little experience of the car itself. The weather was a disgrace but showed the car can handle the rain water. Not the roof of course but electrics seem good and they often are on these cars considering the age now.
It’s really good to see he wants to drive it when he can’t
sorry Brit but we’ve all been there 
wuckfitracing said:
Just a quick question, your speedo is reading 80 MPH, what speed are you actually doing, did you have a sat nav running at the same time. Did it read 70ish on the sat nav ?
Yes had the sat-nav running with speed set to KMH in Europe but MPH in the UK and speedos and sat-nav agree with one and other so speedo is quite accurate in it's reading.Gassing Station | Chimaera | Top of Page | What's New | My Stuff