Starter Motor Part 2

[Guest GeordieJim]

Following my last post I went down the scrappy and obtained a new starter motor. It looks in pretty good nick but still won't work.

 

With the starter motor off the car and wired up the solenoid pulls in then the cables start to smoke. This is the second one to do this so I think I might be doing something wrong. I have wired it up as follows:

 

Looking at the starter motor from behind (i.e. with the solenoid terminals facing you) I have connected the live feed from the battery to the large terminal away from the actual motor. The neutral back to the battery is on the terminal nearest the motor and the small cable from the motor itself joins here. The middle terminal is the live feed from the ignition.

 

Witout the main battery feed attached the solenoid works fine. What I have noticed though is with the solenoid pulled in there is no resistance between the main battery feed and the neutral terminal, which I presume is why the cables are smoking when I have is connected up. I would have thought that there should be no continuity between the live and neutral.

 

The connection between the live feed and the solenoid tip seems to work OK, i.e. when the solenoid is in the tip of the terminal become live. Also, I noticed that the solenoid plunger is always connected to the neutral , which surpised me.

 

I am doing something wrong or have I just been unlucky? Is a trip to Halfords required for a new one?

[Guest TerryBarry]

Hi Jim,

The negative ( earth) cable should be connected to the body of the starter motor, not to any of the terminals on the soleniod.

Using a nut and bolt connect it two one of the mounting holes.

With the starter motor in position mine is connected to the top starter mounting bolt of the three.

The other two sound correct.

HTH

Terry

[Big Jim]

as Terry says, connect the -ive lead to the starter body, then the +ive lead to the large terminal that is on the solenoid with nothing connected to it. If you look, the other one is bridged across to the main motor windings. Then, with another piece of wire connected to the +ive, touch the small terminal on the solenoid, this should kick the solenoid in, throwing out the drive gear, and spinning the motor.

[Guest GeordieJim]

Thanks chaps, I'll give that a try tonight when I get home. I must be going mad though because I definitely can't remember the negative being connected to the starter motor body. Must be those long nights in the garage.............

 

When I was playing with it yesterday the correct method must have been the only one I didn't try. Never mind.

[Big Jim]

When it's on the engine, it "earths" through the engine, and subsiquently the earth strap, you don't have a specific negative lead to the starter, although it's a good idea that the earth strap is bolted close to it.

[Guest Guy]

Mine has a seperate 0V for the starter motor and an earth strap from the top of the engine, that's how it was in the Sierra.

 

Just a note, the out of tank injection fuel pump case is connected to the 0V terminal. If you haven't rubber mounted it (you must do this) then the 0V will be connected to the chassis. If you don't have a proper 0V retern from the starter motor to the battary then there could be a path from the engine through the chassis, across the fuel pump and back to the battary via the pumps 0V depending on how you wire your car. 300A through the pump is bad.

[Les Welsher]

Jim,

when the soilenoid is energised it pulls the motor gear forward and also links the two large terminals on the back of the solenoid which gives power from the battery to the starter motor. By putting the +ve onto the one and the -ve onto the other you are literally shorting out the battery when the solenoid is energised, no wonder it's smokin.

Just put the earth on the body as others have said and every thing shoud work fine.

The earth should ultimately be placed under the bell housing to engine bolt that is just above the motor.

 

Les

[Guest Fred2b]

Is the earth strap on the RH really necessary?

I have not bothered with it and everything seems to work ok?

Regards

Fred

[Big Jim]

Yes, the earth strap to the engine is most necessary, as the engine is rubber mounted. The starter motor draws a lot of current (that's why the wire is so thick) also the alternater can put out up to around 30 amp, and as stated the earth strap is the -ive of both circuits, otherwise it earths through throttle cables and the like, now that can be amusing!

[Guest TerryBarry]

On my '89 2.0 carb'd Sierra the major earth cable connections were:

1. Battery -ve to upper starter motor bolt

2. Battery -ve to body

3. Body to rear stud on inlet manifold

4. Body to gearbox rear mounting bolt

5. Body to bonnet

 

I'm not sure what #4 was there for but when I find it I'm going to put it on

 

Terry