Clicking Distributor

[ollieplimsoles]

Hi Folks,
I have a 1984 500SEC with 148K on the clock. The car started to idle unevenly shortly after I bought it in August past. This roughness was especially noticeable waiting at lights and under acceleration at low revs. I could hear a clicking from the distributor and reckoned this was due to arcing. I then replaced the distributor cap and this seemed to help - and then the problem returned shortly afterwards. I have just replaced the rotor arm (yesterday)and again after a short improvement the clicking and uneven idle have returned

Any ideas guys? The rotor arm was black and burnt so something ain't right. Other than this the car is running well with plently of lift and it sounds and feels generally smooth when cruising around 55 - 60mph. Everything about the engine is standard except that it has an in-line fuel catalyst fitted by John Hayes to allow use with unleaded.

Interested in your replys.

Thanks in advance.

Mark S.

 

[Brian WH]

Is the distributor loose on it's clips, or maybe there is arcing from inside the plug leads causing the noise. Also check the rotor itself, not the arm, for wear or looseness. It cannot be too bad if there is no loss of power.

 

[ollieplimsoles]

Thanks Brian - will have the car out again next week and I'll check each of your suggestions.

Regards,

Mark S

 

[bibamus]

Have you tried the plug leads? I heard a slight knocking from mine sometimes at idle, turned out it was one of the plug leads. I also had the same symptoms on a Honda Goldwing, I thought the engine was knocking but it was a faulty plug cap ( phew!)

Allan