Is there such a thing as a weak start motor?

Also sprach Ted :-

Since you haven't said - I'll assume for now it's a petrol engine.

Yes, because the oil is thicker (making the engine harder to turn over) and the fuel doesn't vapourise so easily (making it less likely to fire straight away).

However, the most likely cause is that the battery is marginal. Being electrochemical devices they depend on the speed of reaction to provide an acceptable current. As the temperature falls the maximum current available also falls. You've shown this yourself by charging the battery

- this probably didn't actually charge it much, just warmed it up a bit so that it could do its job better.

You don't seem to have any other evidence for suspecting the starter motor - or do you?

If it's a diesel then cranking speed is very important, as as the glowplugs if fitted. If you don't have glowplugs then the cranking speed is even more important. Both rely on a good battery.

Yes its a 1.6 nissan petrol carb engine. Well its the original starter motor, still starts the engine, but sounds different to what it used to, is this a symptom of a weak/failing starter motor? The lucas battery is just over 3 years old , a couple of months after the 3 yr warranty (usually get longer than 3 yrs out of a decent battery in my experience?). Headlights still bright when its struggling to start it though in cold. Or could the battery still be weak to start the car but powerful enough to light the bulbs?

Some of the connections may be corroded. Try cleaning the battery terminals and also where the main leads connect to the starter and to the earth.

Rob Graham

Given that the headlights aren't dimming, it is more likely to be a bad connection between the battery and the starter motor. Only once I'd checked for bad connections, and ensured that the starter is getting enough voltage when cranking (10.5V minimum), would I consider changing the starter motor.

To check for bad connections, you want to place a voltmeter across each battery-starter connection in turn, and get someone to crank the engine. From the battery to starter on both leads, you ideally want less than 0.5V off a drop (ie. between the battery posistive and starter solenoid, and also between the battery negative and starter casing)

Could be you're using the wrong grade of engine oil - especially if it's the £1.99 for five litres of 20W/50 from Wilkinsons!

Darren

I would be suspicious of this as well. Had a rover diesel that had slow cranking speed. Put new battery on and it seemed to cure things for a while. Then one day the motor failed to turn and then smoke came from behind the dashboard. The earth lead bonding the engine to the chassis had been slowly fracturing strand by strand in the connecting lug. When the last one went all the current found another earth through the wiring loom behind the dash.

Yes :-). Try jump starting it , if that works then it's the battery, if it starts more easily after a couple of hours charge on a battery charger it's the battery. If neither of those helps then it's still probably the battery but check the earth lead to the body & the one from the body to the engine aren't loose or corroded.

Sounds like a poor connection to the starter, as most draw *more* current when faulty due to shorted turns in the windings.

If you've got a DVM, set it to volts and measure from the battery *earth* terminal to the starter body while someone operates the starter. This will give the voltage drop between the two. Should be less than 0.5 volts. Then do the same from the battery positive to the starter terminal. Again, should be less than 0.5 volts.

Lots of good advice which should all be checked out first, but if none of it works, yes, there could be a fault with the starter motor . . . last time this happened to me it was one of the brushes that was faulty and had then damaged the commutator . . . new starter cranked it over about twice as fast . . .

I went through the cycle of . . . "works ok apart from on the coldest days in winter . . . for two years" . . . until I got sick of bump starting my own car . . . and removed and dismantled the starter . . .

Girlfriends Mondeo is going the same way too . . . and that's it's second starter . . .

Fd

New brushes then before the commuter gets damaged?

Also sprach DuncanWood :-

Almost. It may still be a poor connection - but between the battery post and the cable clamp. Though that's not likely in this case 'cos the lights aren't dimming.

I should really pop it out and see what's going wrong with it . . .

Fd

IMHO the most usual things aren't fixable - shorted turns in a winding, etc. Can't see I've ever seen a starter with worn brushes.

Aye . . . I was wondering if it was a lubrication problem . . . makes a funny noise just after it disengages . . . kinda like a dry sintered bearing . . . last one wouldn't engage and couldn't be persuaded to be reliable thereafter, this one is only 5 years old . . . pretty poor . . .

Interestingly her 110K mile Mondeo costs 1.5->2 times the annual maintainance costs of my Audi 100, which is on 250K miles and does at least twice the annual milage . . . her next car will be a starship milage autobahn-barge I think . . .

Fd

Certainly worth removing and stripping. The pre-engage solenoids on Lucas starters give as much trouble as anything. But if the copper plating on the solenoid armature has gone causing it to stick through corrosion, replacement is the only real option.

IMHO it's sometimes down to the starter position on the engine - too much muck thrown at it or too close to the exhaust, etc. And of course a lower annual mileage car might just have the starter in use more often through shorter journeys.