How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Marty Your Own Question
Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 54019
Experience:  Bosch Certified Master Tech. Over 35 years experience.
Type Your Mercedes Question Here...
Marty is online now
A new question is answered every 9 seconds

1986 560 SL..cold start..hesitation..timing chain..tensioner

This answer was rated:

1986 560 SL:Rough running at cold start and smoothes out after 5 minutes. Slight hesitation from dead stop after car is warm. Changed plugs and wires, timing chain tensioner, fuel pressure regulator, warm up regulator,and cleaned fuel injectors. All the above has made a huge difference but still not quite right. Fuel mixture is a little rich as it does idle just a hair fast. Plan on having mechanic adjusting this week. Any suggestions?
HiCustomer has the car been sitting awhile? Is the anti lock warning light on?

Customer: replied 8 years ago.
The car has 128000mi.currentle. The previous owner only put 900 mi.on it in the last 8 months then traded it in on a newer SL. No warning lights are on.
Ok, when you say that the mixture is a little rich and that it idles fast what do you mean? How do you know it's rich? How fast is the idle speed in neutral when fully warmed up?
Customer: replied 8 years ago.
In neutral it just sounds like it is slightly racing. The tach. needleis between 5 & 10. In drive on leval ground, without touching the gas pedal, it will accelerate ito about 7mph.

Ok, your idea about the fuel mixture adjustment is good but you need to make sure that the adjustment is done properly. A lot of times what I see is mixture incorrectly adjusted in an effort to lower the idle speed. If the car is idling too high that needs to be addressed separately from the fuel mixture. I would have the mixture checked and if leaning it out results in a too high idle then the idle control system will need to be diagnosed. You've had a lot of work done to the car already. One thing I would want to make sure of is that the camshaft timing is correct but I'd only address that if these other things didn't turn anything up. Start with your adjustments and let me know what you come up with.



Marty and 7 other Mercedes Specialists are ready to help you
Customer: replied 8 years ago.



Thanks for allyour help. I am glad that Iam on the right track. Hopefully, my mechanic will get the adjustments done in the next day or two. If that doesn't do the job, I will suggest

the camshaft timing. I would like to let you know the final outcome. How can I get back to you with that info?


Thanks again,