ditchlewis
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| posted on 19/3/07 at 10:53 AM |
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Should the earth lead smoke ????
Hi Guys
I continue to have problems with starting my car. The starter motor works well but the battery seems to loose it punch in about a minute or two.
I have 3 earth leads on the engine and starter motor. All of which have little of no resistance when checked with an electrical meter.
The engine has been running before and the timing has been correctly set so it's not likely a mechanical problem.
Duff battery? It’s the second one that has died on me if it is.
What I have noticed is that the earth lead to the battery does start to smoke after a bit of cranking. I assume that I am trying to pull to much power
through it.
Does anybody know if the effectiveness of a cable to conduct electricity reduces as it heats up? This may explain the rapid slowing of the starter
motor.
I’m planning to put a second earth lead on the battery and also a second live lead to the starter motor, do you think this will help.
After this I’m almost out of ideas.
Regards
Ditch
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JonBowden
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| posted on 19/3/07 at 11:02 AM |
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Single earth leads should be enough.
Most likely problem, I think is dirty connections
I take it the earth leads are really heavy duty - at least 1/4in diam conductors
Jon
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Bob C
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| posted on 19/3/07 at 11:06 AM |
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short answer NO - get some proper sized wire!!! :^)
Bob
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David Jenkins
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| posted on 19/3/07 at 11:10 AM |
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Ditch,
What do you mean when you say "earth lead" - do you mean one of these?
(I should have had a look when I was at your place...)
Anything less than one of these is likely to fry, and will severely limit cranking current. You should only need one!
Give me a call if you want any more help.
David
[Edited on 19/3/07 by David Jenkins]
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DarrenW
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| posted on 19/3/07 at 11:18 AM |
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Any cables that smoke is bad news. Excessive heat is not good for the copper as well. Cranking over for excessive periods of time will warm the cables
up but smoke is very bad.
Id strongly recommend replacing the leads and also ensure all connections are very clean (not just oil free but bright metal) and tight.
I had an issue a while back with mk1 golf - didnt crank over very well at all. Fork truck bay at work made me up some new battery leads - cured it.
The new leads were at least twice the thickness of the originals.
When i wired up earths on ZR, i took battery to chassis earth to a point close to starter, and connected starter earth to this same point. Ive had no
issues with that.
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Volvorsport
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| posted on 19/3/07 at 11:25 AM |
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the resistance goes up with heat .
did you use the wiring of your donor car ?
www.dbsmotorsport.co.uk
getting dirty under a bus
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iank
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| posted on 19/3/07 at 11:34 AM |
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What diameter cable are you using for the earth lead? how long is it?
As above, smoke is a sign that there is something very wrong. Take care people have burnt out cars by using undersized wires.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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Bluemoon
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| posted on 19/3/07 at 11:35 AM |
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You say the resitance is low, but this is very difficult to measure, as even an 0.1 Ohm resistance would stop the starter working.. Remember the
starter can draw upto 100A or so, and requires a very large cross section wire.....
Dan
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02GF74
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| posted on 19/3/07 at 12:08 PM |
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quote:
Originally posted by ditchlewis
I continue to have problems with starting my car. The starter motor works well but the battery seems to loose it punch in about a minute or two.
what exactly do you mean by this? ARe you cranking over continousuly for a minute or two? Or for maybe 5-10 seconds, wait same time, then
repeat.
I have 3 earth leads on the engine and starter motor. All of which have little of no resistance when checked with an electrical meter.
what diameter/length cable are you using? where are they connecected?
The engine has been running before and the timing has been correctly set so it's not likely a mechanical problem.
why hgas this started to happen of of a sudden? car left unused for a long time? have you check spark is good? static timic good? fuel
is good and reaching engine? what makes you so certain it is not igntion/fuel problem?
Duff battery? It’s the second one that has died on me if it is.
What makes you say that? Has this battery never worked?
What I have noticed is that the earth lead to the battery does start to smoke after a bit of cranking. I assume that I am trying to pull to much power
through it.
that is bad - which earth lead - you mentioned 3 leads. the fact that you are heating up leads kinda shows your battey is doing its job
Does anybody know if the effectiveness of a cable to conduct electricity reduces as it heats up? This may explain the rapid slowing of the starter
motor.
metals increase in resistance as they heat up; I am not sure that this will account for motor slowing down; - see first quyestiojn - for
how long are you cranking the motor? The battery will tire too so that will add to the slowing down., Also the internals of the motor - will heat up
so again less current - starter motors aren't intended to be run for a long time,
I’m planning to put a second earth lead on the battery and also a second live lead to the starter motor, do you think this will help.
depends on the leads you have now and how they are wired and where you plkan to put the new leads and their size.
After this I’m almost out of ideas. there are some question that need to be answered ^^^^ before ideas can be proposed.
You must have a solenoid - is there a separate unit or part of the starter motor?
[Edited on 19/3/07 by 02GF74]
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ditchlewis
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| posted on 19/3/07 at 12:10 PM |
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looks like cables are to small
looks like the cables are too small then
I've used the donor ones that had a much smaller engine.
the smoke is comming from the ende of the terminals not the cable covering as that is only hot to the touch.
i will replace the battery leads with the biggest cables i can find (with in reason)
Many thanks lads.
Ditch
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ditchlewis
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| posted on 19/3/07 at 12:10 PM |
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looks like cables are to small
looks like the cables are too small then
I've used the donor ones that had a much smaller engine.
the smoke is comming from the ende of the terminals not the cable covering as that is only hot to the touch.
i will replace the battery leads with the biggest cables i can find (with in reason)
Many thanks lads.
Ditch
PS have you any other ideas ? what would kill a battery other than a constant discharge?
[Edited on 19/3/07 by ditchlewis]
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02GF74
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| posted on 19/3/07 at 12:19 PM |
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quote:
Originally posted by ditchlewis
looks like the cables are too small then:
not necessarily
the smoke is comming from the end of the terminals not the cable covering as that is only hot to the touch.
this is now starting to narrow down the problem. It could be a poorly made (did you crimp it?) or corroded terminal on the cable or the
intereface between the terminal and what it is being connected. Remove the terminal and give it a good rub down with 400 wetndry until it is shiny
metel, then do the same with the metal that it is connecting to be it chassis, battery, etc.
[Edited on 19/3/07 by ditchlewis]
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BenB
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| posted on 19/3/07 at 12:21 PM |
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quote:
Originally posted by ditchlewis
PS have you any other ideas ? what would kill a battery other than a constant discharge?
[Edited on 19/3/07 by ditchlewis]
Being deep discharged by high cranking currents due to dirty contacts on an earth wire?!?!
Don't forget Ohm's law. V=I/R. Even if you're resistance is 1/10ohm (ie so low most multimeters can't measure it) and 100A,
you're looking at a 10v voltage loss- thats a lot of watts to get rid off!!! Hence the smoke!!
I'd get new leads and gently abrade where they're contacting to get a low resistance...
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ditchlewis
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| posted on 19/3/07 at 12:23 PM |
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in reply to 02GF74
I crank for 5 to 10 secs, then leave it the same and then try again. over a period of 2 mins the speed of the motor decreases rapidly.
All are about one foot long and are 10mm diam approx. (David I ve got the plastic coated type not the one shown in your post).
the car has been left for 5 months approx and yes the petrol has evaporated, but as the engine wont crank over enough to get petrol through then i
cannot check. i have checked spark and there is a spark.
the battery has worked, it was new 6 months ago, as was the one before that, its just that they seem not to hold charge. left one on trickle charge
for a week and it went totally dead
motor is new and tight, still needs to run in, that i know will add to the loadings.
i used the vicky green wiring loom and i don't remember a separate solinoid so i think it is part of the starter ???
ditch
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nludkin
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| posted on 19/3/07 at 12:24 PM |
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I had exactly the same problem when I used the old leads from the donor car. The very second I got some braided earth leads from Halfords the problem
went away and the car starts first time every time.
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saigonij
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| posted on 19/3/07 at 12:53 PM |
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make sure that when you fit earth leads that the metal you are connect them to is just that - e.g. if you are bolting the earth lead to the chassis,
make sure you are bolting on bare clean metal - not through powercoating or anything like that.
I had a simular problem on a capri i had freshly painted - i attached lots of earth leads but the starter still woud lnot turn the car over. i then
decided to sand the area of body work where the earth was attached to bare metal - cleaned up the earth lead connector and bolted it back up. this
made all the difference...
so, with any earth lead, make sure the contact is clean and bare metal. 9/10 "wiring / starting" issues have been solded for me by
cleaning the earth points.
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saigonij
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| posted on 19/3/07 at 12:55 PM |
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that should have been
9/10 "wiring / starting" issues have been SOLVED for me by cleaning the earth points.
( cause i was typing and eating an apple at the time!!! )
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iank
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| posted on 19/3/07 at 12:58 PM |
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From http://www.vehicle-wiring-products.co.uk/VWPweb2000/cables/cables.html
mm^2 OD Amps
16 7.5mm 110
25 9.2mm 170
40 11.8mm 300
60 14.5mm 415
I'd guess you have a 9.2mm OD earth lead which sounds marginal at 170 amps. Personally I'd try getting some of the 300Amp cable.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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David Jenkins
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| posted on 19/3/07 at 02:14 PM |
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Ditch,
Step 1 - clean up those connectors, and the metalwork they bolt to. Nice and bright and shiny! Also make sure that your battery connections are also
clean, shiny and done up tight.
If that doesn't do it, Get a big braided strap from Halfords (they'll be near to the batteries) and make sure that you have a clean and
tight connection between the chassis earth and the engine. You only need one strap! 
It doesn't take many failed starting attempts to drain a battery, especially if it takes a lot of effort. Your battery may well be OK after a
decent recharge.
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02GF74
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| posted on 19/3/07 at 02:28 PM |
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from the very frist post, it seems the engine did start reliably with the cables so it does not seem like that is the main problem.
anyway; the wiring shold be as follows.
1. 0V battery - cable - engine block
2. engine block - earth strap - chassis (or use cable)
3. 12 V battery - cable - solenoid
4. if solenoid is spearate, then solenoid - cable - starter (does not seem like it to me.
now all you need to do is to ensure the connections and connectors are sound (clean to bare metal and tight) for 1 and 3 to get the starter spinning.
Do this first before buying fatter cables.
Wih battery not keeping its charge, if you disconnect leads from batery does it still happen, if yes, battery is dead, buya a new one, IF not, then
you may have bad alternator or something else connected that is draining the battery - needs further investigating.
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David Jenkins
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| posted on 19/3/07 at 02:35 PM |
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No - he's always had a problem with starting using the starter. Initially it was a duff unit, then the replacement was duff, so this is the
first go with a starter motor that actually spins!
The engine itself will run if the car is push-started, so there's little chance of timing errors or other engine issues that would otherwise
stuff up starting. It is a tight engine though.
My guess is that getting good connections with correct-sized cables will solve the problems.
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TangoMan
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| posted on 19/3/07 at 02:37 PM |
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I would think 3 10mm earth leads should be plenty (and then some!!)
Have you checked the starter motor. It could be that you have a short under cranking which sends much of your power straight to earth. This would
explain a quickly discharging battery and the smoking cables.
I am not sure what current your starter should draw but it may be worth testing it.
If you have a set of jump leads, try connecting them both from battery negative to engine or one from body to engine and one from battery earth to
engine. This will verify if your earth leads are the problem.
Edited 'cos Dave Jenkins post came in while I was typing. If the starter is OK then look elsewhere. Timing/ Very tight engine etc.
[Edited on 19/3/07 by TangoMan]
Summer's here!!!!
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iank
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| posted on 19/3/07 at 02:57 PM |
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quote:
Originally posted by TangoMan
I would think 3 10mm earth leads should be plenty (and then some!!)
Have you checked the starter motor. It could be that you have a short under cranking which sends much of your power straight to earth. This would
explain a quickly discharging battery and the smoking cables.
I am not sure what current your starter should draw but it may be worth testing it.
If you have a set of jump leads, try connecting them both from battery negative to engine or one from body to engine and one from battery earth to
engine. This will verify if your earth leads are the problem.
Edited 'cos Dave Jenkins post came in while I was typing. If the starter is OK then look elsewhere. Timing/ Very tight engine etc.
[Edited on 19/3/07 by TangoMan]
It's the battery earth lead that smokes, only one of those. Three engine earth's will be more than enough as you say.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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Chippy
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| posted on 19/3/07 at 05:39 PM |
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Just a small point, but your engine should start within the first couple of seconds cranking, if it isn't then something more than just the
leads is at fault. Ignition and valve timing, carburation/injection should all be checked, (again), to ensure your giving the best chance of it firing
up. HTH, Ray
To make a car go faster, just add lightness. Colin Chapman - OR - fit a bigger engine. Chippy
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David Jenkins
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| posted on 19/3/07 at 06:02 PM |
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One other thought - Ditch had to "adjust" the second starter motor with a hammer; I wonder if it's not running at its best
efficiency...
...anyone in the Ipswich area got a known working Pinto starter that could borrowed for an afternoon? Just to exclude that possibility...
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