Can't get my 280SL to idle right...

[snjjahshan]

Hey all,

I've had a few problems getting my 280 to idle properly.
I'm not a mechanic nor do I have a good grasp of how it all works. So excuse my lack of expertise in this area.

The symptoms:
- When hot idle is at around 800-900 and at times it jitters above 1000 and oscillates between 800-1000 in neutral/park.
- When putting the car into reverse while hot it will almost always stall.
- When the cold start solenoid is on it idles quite high between 1300-1600 rpm in neutral/park and then down to 1000 in gear.

Where should the engine idle?
Cold in neutral/park
Cold in gear

Hot in neutral/park
Hot in gear

If I'm happy with the idle while hot in neutral/park (around 800) is it possible to increase the idle while in gear without affecting the idle while in neutral/park? I can sort of hear you saying, "what drugs is this guy on" apologies in advance.

Hope you can help?
Regards,
Saleem

[Larry & Norma]

The constant speed solenoid should increase the revs or at least stop them falling too much when put into gear.
Sounds to me like you have other problems, follow the set up tour in the tech manual before doing anything
else might be a good idea.

[Michael C]

What year is your 280SL?  In 70 & 71 the constant speed solenoid is only used for the A/C.  As part of the smog set up the later models have a vacuum operated dashpot that opens the butterfly a little at idle on the intake when in gear.  (It's a pain in the a**) The idea is that it leans out the car a little when in gear raising the idle speed at idle.  If you have a later model check to make sure it is adjusted correctly. 

If in fact it is an early model, check the linkage and CSS.

[snjjahshan]

Hi Larry and Michael,

Sorry for my late response, it's taken a while to get through the whole tour for getting the idle right.

I'm happy to say that I've got it idling really nicely. Possibly a little too high in neutral but I'm still going through the adjustments.

My 280 was manufactured in Jan 1969 and delivered to Sydney Australia.

Thanks for the help.