starter problem - earth strap so hot I cant touch it

[Alex56]

hi

I've got a 2.1 DJ and I've been trying to solve a number of electrical problems using the Wiki but I need to ask a question!

I changed the starter and the battery for new ones from GSF and cleaned all my earths and contacts, and afterwards the engine would turn over fine but only run for a few seconds.

Reading back through old posts on this forum I decided that I had somehow disturbed the connections to the AFM when I removed it to get to the starter bush, so it wasnt sending its signal.

So cleaned up those contacts on the AFM, fresh charge in the battery, and tried to start it today.

A new problem has emerged! The starter turns very very slowly (remember new starter and freshly charged new battery) and the earth strap from the battery to the body is so hot I cant touch it.

I have no idea why this has happened, I'm genuinely baffled since yesterday it turned over fine then all I did was clean up the AFM contacts, remove the battery and charge it and replace it.

Any ideas on what might have happened gratefully received.

Thank you

Alex

[clift_d]

I think you should fit a new earth strap.

Generally, lots of heat in a cable = lots of resistance, which probably means the cable is on it's way to failing.

[Alex56]

Thanks Cliff, I'll do that.

Fingers crossed, I seem to be making problems faster than I am solving them...

[clift_d]

In terms of cable size / cross sectional area, typically people quote 25mm2 for a petrol engine.

[937carrera]

if you have one, I would run a jump lead in parallel to the fitted earth lead and see it that solves the problem. This also allows you to try out different earthing points

[ghost123uk]

The starter turns very very slowly (remember new starter and freshly charged new battery) and the earth strap from the battery to the body is so hot I cant touch it.

Just checking, I take it the heavy +ve cable from the battery is not getting hot?

[itchyfeet]

What he is thinking^^^
Earth strap only hot when cranking? Cools to cold at all other times?
if you crank for just say a few seconds to start is it too hot to touch?

[Alex56]

thanks to all for suggestions.

it is now clear to me that a previous owner has used wiring of inadaquate cross section on this van.

the positive terminal never got hot, adding he jump leads stopped the overheating on the neg terminal but the starter continued to turn slowly.

well, this is a simple circuit, and I've decided to upgrade it. I figure if its not the battery and not the starter then the problem must be in the wiring so I'm going to renew it. Whilst I'm doing it I will move the battery to the back of the Van to shorten the runs.

So, I'll report back when I've done it, thanks again to those who helped

Alex

[CovKid]

Alex, all you need to know:

https://club8090.co.uk/wiki/VW ... ain_cables" onclick="window.open(this.href);return false;

I've given links to where to purchase the terminals. Do it well and it'll be good for another 30 years. You shouldn't need to relocate battery. Good luck.

Ralph

[937carrera]

Alex,

I think you have proved that the earth stap is failing, so you should certainly replace that.

Before you start replacing the +ve cables I wouldn't assume that the starter is good, just because it is new. I have read that you cannot test a T25 starter off the vehicle because when you do that the armature comes too far forward and the windings rub against the case (or something like that).

I would be tempted to try and test the starter in-situ, using your battery and a set of jump leads. That way you are eliminating everything except the starter and the battery you are using to test it. If it still turns over slowly, and the battery has a decent charge, then the problem is the starter. If not, then it looks like the other wiring.

Hope that helps

[Alex56]

thanks for that, will test starter on van with short direct cablig.

Ralph, I know you used what you had, were you concerned that the factory installed battery cable is thicker than your replacement? and am I reading it right that you used the same thickness between battery and alternator? is this because the battery to starter is less thick (or cos thats what you had)?

Part of my thinking with moving the battery to the back was so i could use 'off the peg' cables rather than make my own, i'm not confident in my soldering, but the thickness vw used does not seem to be easily available.

The factory cable seems massively thick, what are your thoughts on this?

Thanks

Alex

[CovKid]

The cable I used matched/exceeded the cable it replaced. It was industrial multi-strand comparable with earth cables on mig welders. In fact the cable is green & yellow but the colour matters not. Its more the fact its up to the job. You can get such cable at electrical wholesalers - in red and black too.

I used the same stuff from alternator to starter as mine is a 90amp alternator and therefore has a nut on the back that readily accepts the same sized lugs used on the starter. It made sense to just upgrade the 6mm stuff that VW used so I have thick cables throughout. This all provides more than I need to power headlights (which are now nice and bright even on stock bulbs), charge batteries and start engine.

Providing you have a gas soldering iron, and as I say, ALDI sell them from time to time, soldering thick stuff is easier than soldering small stuff in my opinion.

[Alex56]

thanks Ralph, I think I'll give it a go. I have a nut on the alternator too so I'll just follow your wiki... thanks for your reply

Alex

[CovKid]

Don't forget to pop some shrink tubing on and push it up out the way before soldering the lugs. When cool, push it back over the joint and use light heat to shrink it down. Shrink tubing seals the join nicely and keeps out moisture.

I found the best way to calculate how much insulation to cut back is cut fractionally less than you think as the insulation will always roll back a little due to the heat. Worth doing a practice one. The lugs come with a small access hole to run the solder in. Takes a minute for lug to get hot enough (keep torch midway along lug) but once it does, soldering is really easy. Dip the bare cable in flux first.

The only thing to bear in mind is that the cable will accept solder forever, particularly if the lug is pointing upwards and you can end up soldering 3" of cable by capillary action if you overdo the amount, so get the angle right (vice helps) so lug is pointing down slightly. You need just enough to fill the void and get a good connection - nothing more.

Done well, these cables will almost certainly outlive you. I really enjoyed doing those - quite satisfying.

[bobswais]

copied this over from other link, might be useful, got my old starter refurbed to find out what was going wrong, and it was a cooked solenoid. my new one is still on the van but will be coming off soon ! original starter motors refurbed cab be better than the cheap pattern parts.... if you got hot wires, either solenoid is shot or wired it backwards somewhere, check earths. covkid gave loads of good advice.....