Dynamo Problems continued!

[Keith]

Sometime back the dynamo on my MM series car overheated and failed. I have since changed the dynamo, fitted a new battery and replaced the regulator. The dynamo still runs hot, in fact after a short run in the car, you can hear fizzing from the battery which I assume means its charging...
Should this happpen as the battery is new, should the dynamo run hot?.

Help.....any suggestion on some tests I could run would be much appreciated, as I don't want to burn this dynamo out, as it took ages for me to find the MM replacement.

If all fails, anyone know a good auto electrician around the Dunstable area.

Thanks Keith

[Welung666]

Keith, I have a limited knowledge of auto electrics and an extremely good tester. As I'm not far away if you need any help just holla.

Lee

[Keith]

OK thanks Lee, I do have a multi meter just need to know what simple checks I could make.
regards Keith

[Welung666]

If your battery is fizzing then it's more than likely over-charging, test the output on your dynmo first... disconnect the 2 connectors on the back of the dynamo, marked D and F, joint the terminals together with a bit of wire then running at normal idle ONLY, test this wire with your meter (1 lead on the wire and the other to earth). This should be about 14 or 15 volts, any more and it's your dynamo at fault. If not on to the next test... On the voltage regulator take the wires off terminals A1 and A and link them as you did the terminals on the dynamo, then connect 1 lead from your meter to terminal D and the other to earth. Start the engine and slowly raise the rev untils the meter jumps then steadies, normally about 2000 rpm.. the meter should steady out at between about 15.5 and 16.5 volts if it is not in this range it's an easy adjustment by the left hand screw inside the regulator, screw in to raise the setting and out to lower. Once thats is done reconnect everythintg then you just need to check the cut out setting... Connect 1 lead of your meter to D and the other to E, take the cover off the regulator, start up and slowly increase the revs till the cut out (right hand part of the regulator) closes, the reading should be between 12.5 and 13.5 volts. if its outside of this adjust it with the screw on top, in to raise cut off point and out to lower. If the cut off doesn't close then try cleaning the points on it and retry, if it still doen't work you will need to change the regulator.

Try that lot see how you get on.

Jeez! War n peace

Lee

[Keith]

Thanks Lee, I'll give it a go, if I have no luck, I'll drop you a PM and perhaps I could pop around to see you.
regards Keith

[Welung666]

Sure no probs mate, oh if it is the regulator I got 2 or 3 in the garage goin' spare

Lee

[rayofleamington]

The battery should not be fizzing enough to hear it when the engine is running! As mentioned already it sounds rather like overcharging.

Before you do the electrical checks (disconnecting things and connecting terminals together etc..) the simplest chech you can do is check the battery voltage (should be roughly between 12.4v and 13v depending on the state of the battery and temperature etc..)
Then start the engine and check voltage across the battery - at tickover it should be similar, and when you reve to approx 2000 rmp, you should see the meter move up. The meter is likely to jump around a bit as the control box switches in and out the field current to the dynamo, but should NOT go over 14V even if you rev the engine very high.
If it goes over 14v at any point then something is wrong in the control box, so continue with the other electrical checks to re-set the control box (or replace it with one that hasn't been played with)

[Keith]

I did the simple test that Ray recommended before going for the other test Lee recommended. Yes it looks like it is over charging, the battery test without the engine running was 12.67 volts, with the engine running it was peaking at 19 volts......

So I'm not going for the adjustment of the regulator.....I'll keep you posted!......thanks for all the help so far!.

regards Keith

[rayofleamington]

with the engine running it was peaking at 19 volts......

!!!!!!!!!!!!!!

Wow!! Just be glad you don't have a modern car as you electronics (Engine ECU, interior light 'slow fade' module etc... etc...) could all be very unhappy now.
You're likely to have a shorter bulb life (they will have got hotter than normal), and if it has been like that for a while the battery will not last very long, but otherwise the Minor is pretty resilient

Glad you found the problem

[Keith]

Still having problems setting it, the multi meter isn;t that great.

Lee, I;ve sent you a PM, will take up your kind off of assistance with your meter which I'm sure is better than mine.

thanks to all.....

[Welung666]

No probs Keith, I sent you a PM back with my number

Lee

[Keith]

Lee,hope you got my previous PM, can;t make it round until 3 sih today....thanks Keith

[Welung666]

Yea got it m8

Lee

[Kevin]

Hi Keith if it turns out that you dynamo needs overhauling I have a pal who uses a place that does all their own rebuilding on site, almost all the work is on alternators nowadays but if you get stuck I can find out if they will do a dynamo as well, and their stuff is far better than the normal recon parts that are available, you can even have a look around their workshops.

[Keith]

Thanks Kevin, I may well take up your offer, as I have a spare 52 era dynamo that needs servicing also.

I went along to the MM rally Sunday, the 240 mile round trip allowed the compressor the shift some carbon from the Alta head!!!, stopping can be a problem!....got home safely!...

regards Keith

[Kevin]

Ok Keith, I will see him in the next week and will ask him to find out if they will do one and get a price

[Kevin]

Keith I have spoken to my pal and he sees no reason why they would not overhaul your dynamo properly all new bearing etc, probably best to contact me with a PM.