Possible earth problem

[len1]

My engine back plate is fully painted... I am wondering if i have now created a earthing problem for my starter motor..The engine cranks really slowly ..i thought the battery was knackered as it has been sitting on a shelf for 5 years. Yesterday i bought a new battery and its still cranks really slowly. The nut which attaches the solenoid to the started becomes very hot upon cranking...have i created an earth problem and if so can i remedy it by running an earth cable to a suitable ground on the engine. The starter motor worked perfectly 5 years ago.

Thanks

Len

[Mike C]

I'd clean all the electrical connections and try again.

 

If you want a quick check of the earth run a battery jumper cable from the negative battery terminal to a cleaned starter motor mounting bolt and try it.

[RobH]

It may indeed be an earth fault and an auxilliary strap will cure that - but I think you should also investigate why that nut is getting very hot. That sounds like a high-resistance joint which certainly won't be helping and may actually be your problem.

[Austin Branson]

Hi Len, you should have an earth strap direct to the backplate/gearbox. It's at about 1 o'clock. You might want to check that it's well attached, and in good condition.

I think Mike C's idea is a good one.

Let us know how you get on.

Austin

[len1]

Thanks for replies

i certainly do not have an earth strap fitted....

will have another go this morning

Cheers

Len

[elclem1]

Hi Len I have had a problem with a new starter motor. Turning slowly not even enough to turn the engine. I took the starter motor off and tested it across a known good battery and it turned really slowly. It has now been returned to the supplier its the second one I have had that has been faulty I now have put an old one on and no probs. I do have an earth strap fitted but I think its the solenoid that is at fault. Is yours a new one? Albeit 5 years old?

Edited April 22, 2018 by elclem1

[Mike C]

If your feeling a bit adventurous you can momentarily connect the 12V main feed on the starter motor to the positive terminal on the battery with a jumper lead. If it turns over freely the problem's in the solenoid or starting circuit somewhere.

 

Was the new battery you purchased fully charged?

[boxofbits]

The starter would still earth via the threads on the bolts and where you tighten the bolts to the face of the starter flange, but maybe worth checking with a meter for continuity.

 

My 4a starter did similar..just stripped it, washed out with a parts cleaner, lightly greased bearings, reassembled and if spins like new at no cost, so may just need a good strip and clean?

 

Kevin

[len1]

ok so i have taken starter off and connected spare battery up and starter works well , spins quickly and works well , so i will put back on car and try again .....

len

[boxofbits]

ok so i have taken starter off and connected spare battery up and starter works well , spins quickly and works well , so i will put back on car and try again .....

len

You could also have a faulty solenoid. Do you have a jump lead you can connect directly to starter motor terminal just as you have done in your test ? Sometimes the internal connections burn out.

 

Kevin

[len1]

So i have got the starter motor back on, according to the brown manual , there are only two cables to connect white/red and the big positive. yet i have another wire white and yellow hanging down there. tonight i left the white/yellow off and it seems the starter has a bit more life in it. i have put the new battery on charge and it has just stopped charging ,,some 6 hours....maybe it wasnt charged up .....i assume i have done the right thing in leaving the white/yellow disconnected ?

i did put a lead from the starter bolt to the battery and there was no improvement so the starter must be earthed ok just bolted up on its own.

i am thinking .....the battery was flat....and the white/yellow cable shouldnt have been connected.

cheers

Len

[Mike C]

The white and red wire is the correct wire to operate the solenoid. I'd tie off and insulate the white/yellow cable until I found out what it does- people have been messing around with most TR6's wiring for nearly 50 years .

[RobH]

White/yellow is usually the unballasted supply feed from the starter circuit to the ignition coil, used during starting only to boost ignition voltage. If your car has a ballasted coil it may be a bit harder to start without this connected but probably only if it is very cold.

[len1]

Today I have tried the starter after a full battery charge. All is well it's spinning like a good Un. ..just need to get it going now.....

Thanks for replies

Cheers

Len

Edited April 23, 2018 by len1

[astontr6]

So i have got the starter motor back on, according to the brown manual , there are only two cables to connect white/red and the big positive. yet i have another wire white and yellow hanging down there. tonight i left the white/yellow off and it seems the starter has a bit more life in it. i have put the new battery on charge and it has just stopped charging ,,some 6 hours....maybe it wasnt charged up .....i assume i have done the right thing in leaving the white/yellow disconnected ?

i did put a lead from the starter bolt to the battery and there was no improvement so the starter must be earthed ok just bolted up on its own.

i am thinking .....the battery was flat....and the white/yellow cable shouldnt have been connected.

cheers

Len

Len, the white and yellow wire is to do with the ballast resistor wire white / pink in the harness and affects the operation of the ignition light if my memory is right? It gives the 6v coil a full 12v when you operate the ignition s/w. As fitted to late 1972 cars.

 

Bruce.

[len1]

Bruce.

I will connect up that cable tonight and see if it affects anything...I have a new loom but I am pretty sure on the old one that it was connected to the starter motor.

[astontr6]

Bruce.

I will connect up that cable tonight and see if it affects anything...I have a new loom but I am pretty sure on the old one that it was connected to the starter motor.

Len, mine was disconnected years ago as I fitted a high torque starter motor, it was connected to the solenoid and went back to a 12v coil! There was a small male Lucar terminal on the back of the solenoid for this purpose.

 

Bruce

[RobH]

As I said in post 13 above, the only thing this will affect is cold starting - and only if you still have a ballasted coil fitted. If someone has swapped it for a 12v coil the connection will do nothing.

 

It doesn't matter whether the connection is to the solenoid or the starter itself - electrically they are the same point.

[johnmac]

Hi All,

I have just been through a starter motor problem on my 1972 TR6.

It was just going clunk on turning the key, no spin, high amps on the ammeter. Obvious cause would be the solenoid contacts not making.

Removed, stripped, cleaned, rebuilt, refitted. Perfect for a day or so then back to same problem.

So I dug out an very old rusty spare from back of the garage.(from a 2.5PI saloon I believe) Checked it worked on the bench with jump leads. When I removed the rubber cap on the end of the motor shaft (none on the original) I realised that the original was missing its star spring washer

from the end of the shaft! This will let the shaft migrate forward and disconnect the brushes with no spin.

Cleaned painted and fitted the "new" motor anyway as I was on a roll and now starts better than for a long while.

I guess the washer and cap had disappeared some time ago so I did not realise it was gone when I stripped it. Should have looked at the manual I suppose.

 

Just a heads up,

regards, John