1996 C180 Elegance Tickover Problems

[mikk600]

hi just joined the site and wish to say hi and best wishes to all.i have just bought myself my first mercedes it's 1996 c180 auto and am really pleased with it apart from a couple of niggles the seller did'nt disclose.1st the car runs excellent when warm apart from a little up and down fluctuation of the revs at a standstill and also when its cold it will not tickover until it warms up.which with it being an auto is a bit of a pain.and lastly there is a slight knocking coming from the front but with using your wonderful forum have diagnosed this as a belt tensioner on its way out.please can anyone help thanks mikk

 

[Dec]

I will tell you a little story that may or may not apply to you, I do a lot of short runs of one or two miles, last winter I had similar symptoms as yourself, erratic tick over at standstill with engine hot, but a steady takeover if car is put into Neutral or Park.

To investigate I removed the jubilee clips from the air channeling that crosses the top of engine and removed the spark plug cover (I think 3 hex bolts).
I found a small amount of water (quarter of a teaspoon) at the lowest corner of the plug chamber, which was a dirty brown colour. I cleaned and dried the area and plug leads with WD40, this completely eliminated the problem.

Engine was never power washed so I can only attribute the presence of water in this sealed area to my short runs in cold weather i.e. hot engine + cold night = condensation on the underside of the cover which then works its way down the inside surface of the cover lodging at the lowest point in the compartment.

I have changed my driving habits since and avoid the short trips as much as possible.

On starting from cold, revs should be about 1000 and when engine is hot the should be about a steady 750 and dropping slightly when the car is put into Drive or Reverse. In traffic with engine hot, does the fluctuation of the rev’s disappear when the car is put into Neutral or Park?

Dec

 

[Aussie Nick]

Dec I was hoping that you would look at Rmt6668 thread and post today with similar but not identical problems with a W202/220.May also help mikk600.

 

[mikk600]

may have found tickover trouble as small bore vacumn pipe not connected but have since broke down outside mates house.have posted a new thread for any assistance.many thanks for replies.and your kindness is appreciated.

 

[mikk600]

well i've now got my car back with the rvm immobiliser bulb replaced it now starts and runs but still won't tickover when cold.so i'm back in your hands again guys to see if you can help me out once again.many thanks mike

 

[mikk600]

i've just been told the problem could be my maf sensor.only problem is i don't know where to look. i can't find on my car what the guy is telling me it looks like all i can see is a little what looks like a light bulb filiment on the end of two wires which is pushed into the plastic pipe that goes from throttle body to airbox.can anyone shed some more light on the subject please.