Slow cranking starter

[petercook44]

Had problem last week with symptoms of battery failing. Car was slow to crank, released key and tried again a few seconds later and car started fine.Used car at weekend no problems till sunday night at work time.
Car was again slow to crank. Released key tried again still the same. Have tried another battery & starter same outcome.
Is this an easy to rectify electrical problem? All advice would be most welcome

[andmcit]

Sounds like the engine earth to the body isn't as good as it should be. You need to find the lead and clean it's contacts at both ends at the gearbox and the -ve terminal. A nice quick check to see if this is the culprit is to run a
jump lead across from a substantial point of the engines body (lifting eye)
to another main point of the bodyshell making sure the ends are nicely
firmly clamped. See how this helps the power running through into the
starter - additionally try running the cable between the battery -ve and body.

Another item that would then get closer scrutiny would be both battery
clamps as these can get a bit naff in how well they grip the terminals
and get oxidised, check for firm the wiring connections are between the
battery and starter (which it sounds like you've been looking at anyhow)
and then consider whether the ignition lock itself isn't making the
correct contacts it should on starting - maybe try turning it in a more
carefully studied routine to see if any quirks are noticeable though it
most probably could be the electrical contacts in the back of the lock.

Hope this helps relieve the frustrations of your awkward starter!

Andrew

[HDI]

Another potential candidate for the problem is worn starter motor brushes.
I had a a similar sounding problem a few months back. The first symptoms began over a year ago and I checked all the usual culprits as above but they were all ok. Then one cold morning it didn't start and the starter became slower and slower until it wouldn't turn at all, just like a flat battery. When I checked the charge it was ok though. The clue was that the starter was VERY hot ! This indicated high resistance somewhere and after stripping the starter I found the reason. It was full of carbon dust and the 2 earth brushes were worn completely out.
Cleaned the starter out and fitted new brushes and all is now good. Starts instantly, even at -12 recently !

[petercook44]

Thanks for the help guys. Turned out to be broken engine earth