loud POPs, rotor, distributor

[hands_aus]

I had been reading of the value of lubricating the weights of the distributor, so I lubricated the wick in the distributor drive shaft plus the external oil hole.
After re-assembling the distributor I decided to start the engine and let it warm up.
The engine wouldn't start. It just kept on grinding away.
I had a look and the distributor cap had come off. So I replaced it and tried again to start the car.
It gave 2 short sharp loud POPs. Sounded like backfire.

I checked ... the distributor cap was on, so I removed it and looked at the rotor.
The locating plastic tab had been broken off. It was out of position/time.

The rotor is $6.60 from MB Qld.

My question is 'Could there be engine damage from the loud POPs?'

Should I just put the new rotor in and try starting the car or is there anything else I should think about?

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[jeffc280sl]

Is it possible the distributor was not aligned properly (rotor with TDC mark on distributor) when re-installed?  How about the order of plug wires on the cap?  I've made both of these mistakes and the sound the car makes is similar.

Jeff C.
1970 280SL 4-speed

[A Dalton]

If the rotor location tab was broken, either it was not fully seated or the cap was not secured and the rotor locked on one of the cap lugs.
 Most likely just the plasic broke as that would be the weak link, however.. rotate the rotor back/forth by hand and see if it returns via the spring,  this will verify you did not bend/snap any of the advance weight/spring post under the advance plate.

[Cees Klumper]

To further check the condition of your engine, if in any doubt at all, you can first turn it by hand (remove spark plugs first), then crank it without the fuse to the fuel pump in place and without the distributor cap on (so the car cannot start). If the engine turns freely without alarming noises, I would guess it's safe to start for real?
It sounds like you may not have put either the rotor or the cap on just right, causing interference.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[ja17]

Hello Bob,

Yes I agree with the others. Sounds like the distributor cap or rotor was not seated. This probably caused a mis-directed spark and back fire. replace the damaged parts and all should be well. Be sure to get the right fitting rotor. Some versions are a close fit but not quite tight. Ordering by the distributor number may be the only way to be sure. What distributor # is in your car?

Joe

Joe Alexander
Blacklick, Ohio

[hands_aus]

Hi Jeff, Arthur, Cees, Joe,

Thanks for replying.
Obviously I didn't push the rotor down onto the shaft hard enough.

As a test I left the distributor cap off and cranked the engine. It ticked over very nicely with no strange noises.

The replacement rotor arrived this morning so I installed it making sure it clicked into position. It returned freely to the normal position when I manually advanced the rotor.

The part was a Bosch GB603. MB didn't even have it in a MB package, they just added their own sticker to the Bosch packaging.

The distributor is an '051' cast iron unit.

The engine fired right up.

I took the car for a short burst around the local streets and on the free way. The engine was very responsive.

I think the distributor oil wick was a bit dry and the job was timely. It is 5 months since the last oiling.

At what interval should I oil the distributor?

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[Randy Woodward]

Jeff, how are you getting on with your 70 280sl? I just picked one up about a month ago, also a 4-speed. I'm struggling with back-fires when I maintain 4000rpm in 4th gear. I do that for about 5 minutes, and all of a sudden everything goes to hell and I get huge, black back-fires. How has your engine been running?

quote:Originally posted by jeffc280sl

Is it possible the distributor was not aligned properly (rotor with TDC mark on distributor) when re-installed?  How about the order of plug wires on the cap?  I've made both of these mistakes and the sound the car makes is similar.

Jeff C.
1970 280SL 4-speed