The Triumph Dolomite Club - Discussion Forum

It puts full the battery voltage, nominally 12v, to the top of the 6v coil all the time the starter is (or should be) turning, to (over)compensate for the voltage drop that causes, and make it a bit more likely the car will start. It does that by shorting out a ballast resistor, which is often incorporated in the loom, between the ignition switch and the coil.

Graham

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The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.

Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).

Hi Graham, I haven't got a ballest resistor coil, someone has removed it and fitted electronic ignition so I can probably forget that wire eh. Alan

In that case, there's no need for it. But if it's there, the worst it would do is, while the key is turned, give a slightly lower resistance between battery and coil, through the thick wire to the solenoid, avoiding contact losses in the ignition switch and fuse. So it can't really hurt.

Graham

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The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.

Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).

Another good test before you take the starter motor out would be to remove the ignition lead from the starter solenoid and then apply 12 volts directly to the that solenoid terminal. If the starter motor turns over it will indicate that the problem is that you have developed a high resistance in the ignition feed to the solenoid which might be in the ignition switch or the inhibit switch. Obviously you should then sort out that problem but fitting a relay as previously stated does reduce the current drawn and so might get you back up and running.

Hi Graham thanks for that information if I can get a four post solenoid I'll attach the wire, if not and only a three post one is available it will do.
Richard you advocate a relay but do you have any instructions ( as simple as possible as I am a 72 year old novice ) as to wiring and location please.
Alan

I agree with Richard that before you do anything else (except possibly tighten the starter motor mounting bolt) you should briefly connect the terminal on the starter solenoid where the input from the ignition switch connects direct to the battery positive. If there's 12v on the main feed to the solenoid from the battery as well, it should turn the engine unless the solenoid is gone.

But I would also measure the voltage on the main battery feed at the solenoid while the ignition input to the solenoid is at 12v. The main feed voltage will drop a bit as the starter tries to turn the engine, and I'm not sure what a good minimum should be. But if it drops very low and the engine don't turn, then the lead from the battery or the battery terminal must be suspect - though, if it's the battery terminal that's a bad contact, it usually stays open circuit when you let go of the key and you have to wiggle/tap it to even get the lights on.

I think you should test all the possible faults before you take the starter off cos it'll hurt when you kick yourself if it's not that. That test that Richard suggests, along with checking there's a good connection from the battery, should make it clear if its the starter/solenoid or not.

Graham

_________________
The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.

Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).

On most occasions when I have had starting problems it has generally been a bad earth. Either a broken earth strap or the earth is corroded. That is what I would check before doing anything else.

I will try those suggestions tomorrow. Lets see if I understand correctly-
1/ tighten up the bottom motor bolt.
2/ Reconnect the main wire from the battery.
3/ Run a new wire from the battery directly to the solenoid ( quick flash ) where the red and white wire from the ignition would normally go.
If the starter operates there's a problem with the ignition circuit. If it doesn't operate it confirms the solenoid is duff.-Is that all correct ?
Alan

Mount a 4 pole, 40 amp relay on the O/S flitch near the battery. The 4 poles will be marked 30, 85, 86 and 87, take a substantial battery live to pole 30, separate out the White/Red lead from the starter back down to where it meets the main loom, shorten as needed and attach to pole 85. Earth pole 86 and run a new substantial wire from pole 87 to the starter solenoid terminal left vacant by the removal of the White/red lead.

Steve

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'73 2 door Toledo with Vauxhall Carlton 2.0 8v engine (The Carledo)
'78 Sprint Auto with Vauxhall Omega 2.2 16v engine (The Dolomega)
'72 Triumph 1500FWD in Slate Grey, Now with RWD and Carledo powertrain!

Maverick Triumph, Servicing, Repairs, Electrical, Recomissioning, MOT prep, Trackerjack brake fitting service.
Apprentice served Triumph Specialist for 50 years. PM for more info or quotes.

Yeh, I think that covers most stuff except if there's a problem with the main lead down from the battery, or the earth as was said. You'll probably need to use a voltmeter when the starter is operated to see such problems. Is there a separate earth return lead in that setup, or is it through the mountings to the block?

Graham

_________________
The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.

Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).

Yes Graham, I presume it gets its earth from being bolted to the gearbox.which is earthed via a strap to the block from the battery.

I would take off the earth strap to the block and clean it with an abrasive. Even if it is good enough to keep the engine going when it is started, the starter motor draws far more current and the earth could be bad enough to stop it from working.

I have had this on a couple of cars.

Underrated title.

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Current fleet: '75 Sprint, '73 1850, Daihatsu Fourtrak, Honda CG125, Yamaha Fazer 600, Shetland 570 (yes it's a boat!)

Past fleet: Triumph 2000, Lancia Beta Coupe, BL Mini Clubman, Austin Metro, Vauxhall Cavalier MK1 & MK2, Renault 18 D, Rover 216 GSI, Honda Accord (most expensive car purchase, hated, made out of magnetic metal as only car I've ever been crashed into...4 times), BMW 318, Golf GTi MK3 16v x 3

My Dolomites are all 1500cc cars but my assumption is that all the others will be basically the same. I am in the process of producing an article of Dolly Mixture on fitting a relay in a 1500. I never like cutting the original wiring so you will see that I have not done that in the diagram.

Alvera just to let you know I am 74 but it does mean that I have been a Dolomite owner for 43 years now.