My 1976 230 has never been running better, I have the fuel/air mixture set and I had the timing done too. However, More frequently than not, the engine runs on for 5 seconds or so after I turn off the ignintion. It shakes a bit and then shuts down with a whizzz...

Is the timing possibly off and needs to be re-adjusted or is there something else I should check ?

I recently had my rusty fuel lines and vacuum line replaced so this might affect something.

Thanks again guys for saving me grief.

AARON ROCHARD
1976 230.4 W115

Running on after shutting the engine off is called "dieseling"and can be caused by low octane fuel,or if the timming is retarded too much. Try some higher octane fuel or advance the timming just a wee bit. Too much advance, and the engine will "ping" upon acceleration. Good luck.
Bill Lewallen Lexington,Ky.

thanks, I also have been having vacuum problems with my carb, and I'm thinking (from reading the other posts on this subject) that this may also be the problem.

Is the timing something I should mess with or should I leave it to the garage. From what you say, it sounds like just taking the right size allen key and turning the bolt slightly forward clockwise.

Thanks again.

AARON ROCHARD
1976 230.4

You need a timming light to set the ignition timming accurately.Loosen the Allen screw on the clamp of the distributor and rotatate the dist. Not sure which way to turn it, but the timming light will guide you.The timing specs should be in the owners manual.If you don't have it, let me know and I will look it up and send it to you by e-mail.
Bill Lewallen Lexington,Ky.

Thanks guys for all your help. turns out upon using Ultra 94 intead of the (usual 87 octane) the run ons have almost disappeared. I am surprised that this might have been my only problem. It stinks that the cost of fuel is what it is now (~75 cents/litre here in T.O.) I'll try and use mid grade and see what happens.

AARON ROCHARD
1976 230.4

Well there is always another way around the barn. You car has a rather unique anti-dieseling solenoid that if functioning absolutely stops the problem.

What makes it unique is that the system is dead with the car running and activates at shut-off. The solenoid is the large round one one the bottom of the carb that is used for mixture adjustment. With no power (no connection) the thing is just the main jet of the carb. When the key is shut-off a relay powers the solenoid for about four seconds if I remember correctly.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

When the solenoid activates, it turns off all posible fuel, not just killing the ignition. An engine without fuel will not run on.

My first thought here was what Steve said. Take away the fuel when you turn off the engine.

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Benzmac:
Donnie Drummonds
300E
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM
OWNER OF MB AUTOWERKS .COM

To me "dieseling" is really aggravating. Too high an idle speed will exacerbate run on. Another workaround that I use is to turn off the ignition while the transmission is still in drive. The extra drag on the engine will stop it. On a standard shift I will put it in high gear, put a very slight drag on the clutch while stepping on the brakes, and then switch it off. Check the idle speed first.