Starter motor running slow

Submitted: Saturday, Dec 12, 2015 at 18:49
ThreadID: 131108 Views:1492 Replies:5 FollowUps:1
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Starter motor is turning slow with full batteries and a short time (30 sec) cranking the earth lead is so hot it has melted from the connection at the battery. The starter is hot but not extreme. This is on a grader (dresser). Anyone have an idea what the cause is.


I know it is a bit different than a 4WD but maybe someone might know what would cause this.


Cheers Andy
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Reply By: Gary T7 - Saturday, Dec 12, 2015 at 19:15

Saturday, Dec 12, 2015 at 19:15
Earth lead has a poor connection from the battery to the starter. high resistance
thats why it is getting hot. check all connections and joints for volt drop on earth lead.

Gary
AnswerID: 593737

Reply By: Life Member - Fred B (ex-NT) - Saturday, Dec 12, 2015 at 20:04

Saturday, Dec 12, 2015 at 20:04
the crimps on the ends of the cable would have got very hot as well, you will probably need to replace the whole earth cable and clean the surface face on the body where the cable connects.
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Fred B
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AnswerID: 593738

Reply By: Slow one - Saturday, Dec 12, 2015 at 20:30

Saturday, Dec 12, 2015 at 20:30
As said bad connections on either the negative or positive cables, starter solenoid switch contacts, starter brushes or glory help us all, the engine is starting to seize.

Hope you can find the problem.
AnswerID: 593739

Reply By: Ron N - Saturday, Dec 12, 2015 at 20:36

Saturday, Dec 12, 2015 at 20:36
Andy, it's highly likely the bronze bearings on the ends of the armature are worn, allowing the armature to drop and contact the field coil magnets ("pole shoe" in Delco-Remy terminology), making the starter "pole out", or short out.
The clearances between the armature and the electromagnets screwed to the housing are small, even when new - and any wear in the bronze bearings will reduce the required clearance to virtually nothing, making for a short-circuit condition.
The simple cure is new bronze bearings both ends.

A good starter motor repair shop in the old days, would always keep these bronze bearings on hand.
However, it's hard to find anyone who will even repair starters today - let alone keep the bronze bearings in stock.
I have a drawer full of them, I bought most off eBay when people were selling deceased estate stuff from old electricians that had passed on.
You don't use them very often, but they are manna from heaven when you have a wonky starter like yours.

If you take your starter into a dealer or electrical repair shop, they will just tell you it's stuffed and want to sell you a brand new one.
And the reason they do that is because they can no longer repair starter motors at a price below what new ones sell at.

Cheers, Ron.
AnswerID: 593740

Reply By: Allan B (Member, SunCoast) - Saturday, Dec 12, 2015 at 23:39

Saturday, Dec 12, 2015 at 23:39
Andy, there are two clues in your expression..... 1) "the starter is hot but not extreme" and 2) the earth lead has "melted from the connection at the battery".
If the starter is not extremely hot suggests that there was not an excessive current flow through the starter and accordingly, not an excessive current flow through the earth lead. Therefore the heat was generated not by excessive current but by excessive volt-drop in the earth lead, almost certainly by a poor connection at the battery which would account for it "melting".
Either remake the earth lead connection properly or replace the earth lead with a new one.
Cheers
Allan

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AnswerID: 593749

Follow Up By: Member - Trouper (NSW) - Monday, Dec 14, 2015 at 19:00

Monday, Dec 14, 2015 at 19:00
So Andy, have you fixed the problem?? if so what was it. Earth lead or starter motor issues??

Jeff
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