New battery - but stil slow crank speed?

[aka_kerrly]

bearman68 said:

I not judging the cabling and connectors or anything else on appearance. I'm basing it on the fact the battery dropped to 7v when the engine was cranked.

problem, but it's not going to effect the cranking speed.
The next stage is to check the battery is OK, or to measure current.

I dread to think how long an how much I spent with a similar issue. Short term it seemed better with a new battery, new starter, new live terminal but it persisted. Sometimes turning the key the starter would barely turn, then next time it would turn much quicker.

After replacing all the relays and fuses in the starter system, the earth terminal lead from the battery to the gearbox things became significantly better and I thought I'd cured it but then it started playing up again.

The last part I changed was the ignition switch on the barrel. Seemed it had worn out inside and wasn't making a very good connection when it was meant to be sending 12v to the starter solenoid.

This was over a 6month period with half a dozen AA call outs and 2 different garages had looked at it all doing the same umm your battery only just passes a drop test maybe time for a new one.

[bearman68]

Had a problem with an MG BGT one day. It would intermittently cut out or run rough. Been everywhere, had the obvious stuff done - ignition coil, spark plugs, distributer, mechanical timing, carbs etc etc etc.
My initial thought was exactly all those things. But on reflection, the guys that did those things are probably better at them than I am, so it's going to be something different. Thought I would check the primary voltage to the coil.

An oscilloscope on the primary coil showed varying voltage, especially as the engine reved. Replaced the ignition switch, and it was better for months. Then the customer brought it back with the same issue. Eventually found the mechanical rev counter had a metal sheath that was shorting, or sometimes partially shorting the primary voltage on the distributer.

[Sheepshanks]

aka_kerrly said:

The last part I changed was the ignition switch on the barrel. Seemed it had worn out inside and wasn't making a very good connection when it was meant to be sending 12v to the starter solenoid.

So was the suggestion that it wasn't energising the starter solenoid hard enough to fully close the contacts? I don't know if that's possible, but if it was you'd think it would quickly destroy the contacts.

[Ian Geary]

Afternoon all,

Very busy week. Sorry for lack of updates, but here's a final one.

The car had conked out on other side of town last weekend (outside in laws house)

The starter was utterly lethargic, and barely rotated. Yet I wasn't hearing the clicking noise you'd normally hear with a flat battery.

So new starter purchased off eBay for £60

Finally had time to go and fit it today (whilst recharging the new Lion battery for good measure)

With it all installed (very straight forward) the cranking speed was massively different. Easily sounded twice as fast to my ear.

Car fired up almost immediately.

So I can conclude the starter was in fact knackered.

(I had checked resistance/ voltage drop from battery to starter, and starter to earth, and it was zero.)

I probably didn't need the new battery tbh, but it was the easiest bit to try

(Note I had tried to jump it initially, but that didn't work, and I didn't want to screw up my e61's electrics by trying further.

Maybe I should just have got my breakdown recovery bods to trailer it home, but where's the fun in that?

Ian

[Penelope Stopit]

Nice, got there in the end

Did post to your earlier topic https://www.pistonheads.com/gassing/topic.asp?h=0&... that the starter motor was faulty




All's well that ends well