Run On or Dieseling after shut downCORRECTED INFO

[dwsfca]

A friend of mine has a 80' 280 SL that is in need of some help.

I started with the usual(new plugs, points, cap, rotor) and now it runs fairly decent but STILL has a problem at shut off.  It wants to keep running.  :evil:  

I set the timing at 8Deg BTDC with the vacuum line disconnected (it has the vacuum retard distributor)and that eliminated the horrible detonation it had under hard accereration.  

The only way I can get it to shut down properly is to set the Idle speed down to about 500 RPM. With the Idle so low it has a hesitation upon acceleration but runs smoothly after that.

I suspect this car has significant carbon buildup and that is causing it to keep running with ignition off.

Has anyone else experienced this problem?   :?:

Any thoughts?


Dan 68-250SL

I meant to say I set the timing at 8Deg ATDC with vacuum line disconnected.  Is this correct for this year?

My apologies to everyone.  My fat fingers hit the 8 instead of the 7, This is a 1970- 280 SL.  Sorry for the confusion.  Thanks Rodd, Sorry Walter.  

[hauser]

Are you using premium high octane gas?  Low octane can contribute to the 'dieseling' problem.

1969 280sl 5 spd
Gainesville, Fl.

[ja17]

Hello Dan,

Yes hauser is right on the octane issue. The 280SL engine has 9.5 to one compression and needs high octane fuel.  In the US, 92 octane will usually be fine.

Joe Alexander
Blacklick, Ohio

[dwsfca]

I will need to check to see what grade of gasoline she has been using, Thanks Hauser and Joe!

[rwmastel]

quote:Originally posted by dwsfca

A friend of mine has a 80' 280 SL that is in need of some help.

When replying to this thread take note that this is a W107 car.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[waltklatt]

Dan, I believe this is a M110 twin cam 280SE unit.  Check the electrical connections on the fuel distributor.  Other than that, I don't know much about them.
Walter Klatt
1967 220SL-diesel
1963 230SL-gas

[ja17]

Hello,

Yes this is a W107 280SL with a M110 twin cam engine as Walter has mentioned. These were not delivered new in the US. These were high compression and would still need premium fuel.

Joe Alexander
Blacklick, Ohio

[rwmastel]

quote:Originally posted by ja17

Yes this is a W107 280SL with a M110 twin cam engine as Walter has mentioned. These were not delivered new in the US. These were high compression and would still need premium fuel.

Actually Dan edited his post.  The '80 was a typo error, it should have said '70.  This is a W113.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[Douglas]

I had this same issue not long ago on my last Pagoda. It turns out it was a simple adjustment in the throttle linkage. Sorry I can't be of more help, but I would examine the return action of the linkage very carefully.

Douglas Kim
New York
USA

[Ricardo]

Dan
I think you'll find in the archives, references to soot build-up with extended idling. I've had the experience of completely fouling up a set of plugs, by repeated idling bouts, caused by frequently starting the car to move it in the winter and letting it run for 10-20 minutes at idle. After 6 or 8 times of this the car would no longer start and the formerly clean plugs were totally fouled. I think it's partly that these cars run pretty rich until warm and they may be out of adjustment and running VERY rich until warm. It's probably made worse by the idea that one should start the car regularly when it's in storage, to keep the battery charged, etc. or let it warm up every time we go for a little drive, instead of just driving off with the engine relatively cold and disconnecting the battery for the winter and just leave the car sit without starting.

Maybe a long extended hot highway run would clear up the issue if it is carbon build-up?
My 10 cents worth (since two ain't worth nothin')