pos

pos

Well-Known Member
Hello,

I have noticed that when my engine is idling, I can hear the alternator loading its self up for no particular reason, the idle becomes much lower and the fan belt starts squealing. It comes on and off in short bursts between 1 and 5 seconds and then repeats its self a bit hit and miss about ten times a minute. When I am driving at night, with my headlights on main beam, they keep switching between dim and bright (not full beam) and it's beginning to be a pain in the arse. I have fitted a new voltage regulator as well as ensuring that the belt is nice and tight but it has made no difference. I think my alternator has had it. Any ideas?

Thanks,
-Tom
 
Mseries3 said:
Got a GOOD earth? Mine was doing similar.
Click to expand...

I think so yeah. The connection at the battery terminal is clean, and that bolts directly to the back of the transfer box. The earth strap from the block to the chassis looks fine too. I take it that the alternator is earthed through its self? It could well be damaged inside?
 
Take a multimeter and measure the resistance between alt housing and battery minus terminal (terminal, NOT clamp!) -> if more than "0", beep or more than very little (>0.1 ohm): bad
If that's alright, measure voltage in idle. Put on here what you measured.

Cheers

PS by "bad" I mean good, because it's the earth and not the alternator, but as you check the earth, it means the earth is bad...
 
philvy said:
Take a multimeter and measure the resistance between alt housing and battery minus terminal (terminal, NOT clamp!) -> if more than "0", beep or more than very little (>0.1 ohm): bad
If that's alright, measure voltage in idle. Put on here what you measured.

Cheers

PS by "bad" I mean good, because it's the earth and not the alternator, but as you check the earth, it means the earth is bad...
Click to expand...

I don't fully understand what you are asking me to do :confused:
 
pos said:
I don't fully understand what you are asking me to do :confused:
Click to expand...

Do you have a multimeter?
multimeter - Google Search
If not, pinch one, or buy one.

Put it on "ohm", the lowest setting, or the diode test (the triangle/two-lines symbol).
Check that the settings are right by making contact between the leads, in diode mode it should beep, in ohm measurement the needle should go right to 0, digital should show 0.
If that worked:
Engine off:
Put one lead on the alternator housing, the other on the battery terminal. The reading should be the same as before (optimum: 0 ohms, beep...).


For Voltage, you put it on DC mode (straight line with intermittent line beneath), on the next higher setting than 14V (usually 50V).
Engine idling:
One lead on battery minus, the other on battery plus while car is idling. Voltage must be well over 13V, I dont know what the idle voltage for a defender is, must look it up.


Just measure this and put here what you got out, or if there are any more questions, just let me know...
 
philvy said:
Do you have a multimeter?
multimeter - Google Search
If not, pinch one, or buy one.

Put it on "ohm", the lowest setting, or the diode test (the triangle/two-lines symbol).
Check that the settings are right by making contact between the leads, in diode mode it should beep, in ohm measurement the needle should go right to 0, digital should show 0.
If that worked:
Engine off:
Put one lead on the alternator housing, the other on the battery terminal. The reading should be the same as before (optimum: 0 ohms, beep...).


For Voltage, you put it on DC mode (straight line with intermittent line beneath), on the next higher setting than 14V (usually 50V).
Engine idling:
One lead on battery minus, the other on battery plus while car is idling. Voltage must be well over 13V, I dont know what the idle voltage for a defender is, must look it up.


Just measure this and put here what you got out, or if there are any more questions, just let me know...
Click to expand...

Ahh right thank you :)

Well I can tell you that it is charging at 15V (reading across battery terminals whilst idling) because I checked that yesterday. As foe the resistance, that will need to be checked tomorrow.

I'll report back tomorrow afternoon

Thanks,
-Tom
 
pos said:
Ahh right thank you :)

Well I can tell you that it is charging at 15V (reading across battery terminals whilst idling) because I checked that yesterday. As foe the resistance, that will need to be checked tomorrow.

I'll report back tomorrow afternoon

Thanks,
-Tom
Click to expand...

15V? can it be 14.7 or rather more than 15 (rather more or rather less)? If it's 15 it's on the border to "It'll **** your battery"...
 
philvy said:
15V? can it be 14.7 or rather more than 15 (rather more or rather less)? If it's 15 it's on the border to "It'll **** your battery"...
Click to expand...

I'll take another set of readings from it tomorrow and see what I get. It was definitely bang on 15v yesterday.
 
Bushtoy said:
Anything beyond 13.5 is not good.....:D
Click to expand...

you tell that to one of my customers who's alternator spiked to 23v and popped her airbags and burned out the entire wiring loom while she was driving! ( the sides of the battery were ballooned out far enough to make it hard to remove)
 
Bushtoy said:
Anything beyond 13.5 is not good.....:D
Click to expand...

yes, but some "offroad vehicles" charge at 14.7V... and I don't know what the voltage for a defender is, so at 15V I assumed it's 14.7V. If it's 13.5 or 12.8 either rectifier, diode or something else has seen better days...
 
philvy said:
yes, but some "offroad vehicles" charge at 14.7V... and I don't know what the voltage for a defender is, so at 15V I assumed it's 14.7V. If it's 13.5 or 12.8 either rectifier, diode or something else has seen better days...
Click to expand...

My defenders (all TD5's) are around 13.5 and average 2 years per battery....me old seriesIII is up at 15 and eats batteries fer brekky.....but then she's special
 
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