Rotor arm - never seen this happen.

[Pete B]

Bus had been stood for a while, took a bit of turning over to fire up initially and continued to be less than good at starting until I got a chance to have a look at it yesterday (when it refused point blank to start.....). Wasn't in a position to turn it over and check for a spark at the plugs so checked the LT side and all seemed well. A couple of times it had fired when turning the key back from 'start' to 'ignition' which got me thinking on the 'hot start relay' route but of course the engine was cold. Considered the ignition switch itself, especially as it's a random generic dash mounted thing already fitted when it came over from the states.
However, a closer look at the fairly new Bosch rotor arm showed a black 'bubbly' surface on the top. A little light scratching and that part just turned to powder and left this hole. Continuity test shows HT current would not be making it to the end of the arm hence not starting.





New Beru arm and cap fitted and all is well.

At least it is now I swapped no. 3 and 4 leads back to where they should be.... the backfire was like a gunshot and had the neighbours out in droves!!!!!!

 

[67panel]

Happens,arcing between carbon brush and brass ends causing overheating.Bad manufacturing tollerances.I prefer to use one without suppresor ,but you wont get a new one like that!








dave---------likes using old s*it

 

[Trikky2]

Had exactly the same problem on my Audi a few years ago. Mine burnt out in the middle rather than close to the centre like yours.

These suppressor a can fail over time.

The same applies to the suppressed spark plug caps. When they go they affect only one cylinder and cause mysterious hesitations that can seem like carb or coil problems.