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Finding a Electrical Prob

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Arthur from Tas

02-09-2005 04:24:24

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Hi Ken
using your multimeter set on volts range check for any voltage drop or faulty connections on the battery leads. starting between the center of the battery terminal and the engine block. then try the generator / altenator output terminal to the other battery terminal (both paths should read zero).
using that method of checking the extreme connections you work the probes back towards each other along the current path until your reading shows zero. the difference usally being a poor connection or crook clamp to a battery terminal
Try this and then let me know how you get on.
Cheers Arthur from Tassy

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Ken Park

02-09-2005 15:31:35

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Re: Finding a Electrical Prob in reply to Arthur from Tassy, 02-09-2005 04:24:24

Thanks for the response Arthur from Tassy. The problem I have is that I don"t know exactly what you"re asking me to do but I did do this:
With engine running - meter from center of Pos bat terminal to Block gave erratic readings - from ctr of Pos to metal fittings not on block gave steady voltage reading - ctr of neg bat term to bat on alternator gave erratic readings. Without engine running - pos bat term to eng block gave 0 - pos bat to alternator grnd gave 12.59 - neg bat term to alternator bat gave 12.59. I noticed the meter laying on the tractor step while it was running with no leads placed was giving erratic readings as if from radiation.
Is this any help or can you re-direct me.
Ken

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Arthur from Tassy

02-10-2005 03:39:50

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Fix a Electrical Problem in reply to Ken Park, 02-09-2005 15:31:35

Hi Ken
Sorry that I was being a bit vague, but the reason is that old generators of the British types used positive earth systems and they can be found on UK built MF 35's and early 135's as your tractor has a alternator it should have a negative earth system.

your last point is a good observation! the meter was acting as a radio frequency detector, wow!

(leads that have current interupted by sparking give off radio frequency interference. eg try listerning to a AM radio next to a old petrol motor that is running and has faulty ignition leads.)

I drew a picture of the tractors battery circuit using your measurements and your description has told me plenty, check where the negative lead is terminated into the battery terminal clamp for corrosion and the other end should be fasterned onto the engine as close as possible to the body of the starter motor (I use one of the bolts that fasterns the starter), the joint should be bare metal to bare metal. no dirt, rust or paint here please.
make sure that the body panels have one good earth to the tractor motor and also the alternator body has a good earth to the tractor motor.
So we will try and fix the simplest possibility first which looks like a poor earth connection.
Cheers for now Arthur from Tassy

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Ken Park

02-10-2005 08:16:32

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Re: Fix a Electrical Problem in reply to Arthur from Tassy, 02-10-2005 03:39:50

Many thanks to all for the advice. Just for the record we put in brand new battery leads and a new battery. But I think the question of new paint interfering with the ground needs to be checked and today I'll go through all the grounding to be sure. For Jerry, the 12.59V reading was taken when she was not running ... the alternator was checked out and works fine. Also, she's negative ground. One last thought is that we did not replace all her wiring and maybe one of the wires has decayed inside ... but the ones we didn't replace looked good. I will report back and appreciate the input.
Ken

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Ken Park

02-10-2005 12:43:11

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Re: Fix a Electrical Problem in reply to Ken Park, 02-10-2005 08:16:32

FIXED IT!!!!! Thanks Arthur from Tassy (right on the nose) and the other contributors for your time and good suggestions. Everyone was onto the problem except me! It's nice to be among genius. It was the main negative ground lead to the starter bolt where I had painted (the starter was off during the engine re-paint) and we didn't get down there and sand it clean for a good connection before we put the lead back on. Glad that's over with.

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Arthur from Tassy

02-12-2005 20:23:20

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Re: Fix a Electrical Problem in reply to Ken Park, 02-10-2005 12:43:11

Thanks Ken
I am glad that you have found the problem. Cheers for now Arthur from Tassy

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