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Old 10-29-2001, 09:18 PM
Posts: n/a
1986 300E - 3n ew problems after service

I recently had my car serviced because it began stalling at idle (cold, warm, & hot). It was serviced at an exclusive mercedes shop in Orlando that had serviced this car for the last 5 years for the previous owner. They fixed the stalling problem (motor vac, fuel injectors & seals and coolant temperature sensor, distributor cap, rotor, plugs). To me it seemed like the shotgun approach, but, I'm no expert. They also checked, coil, fuel pump, fuel distrbutor, o2 sensor (at one time they said the 02 sensor was bad, but, when I complained about how could so many things go bad at once, they said they cleaned it and it tested ok) $1,200 Total.

Anyhow, when I left the shop, my car had 3 new problems. First was obvious - LONG CRANKING (3-5 sec) cold, warm or hot. Previous to this I could crank the car in 1- 1.5 seconds. I mentioned this to the shop owner, and he said he owned the same car and 4-5 seconds of cranking is normal for this car. Wrong answer. I found a workaround by holding the gas pedal down while cranking. This helps crank in 1-1.5 like before.

However, after I start my car, comes problem number #2 VERY ROUGH IDLE. The car will cough and gasp for several minutes. Occasionaly it may die and I will have to re-crank and lwait for the car to warm up before moving. But, what is odd is that this happens after cold and warm starts but gennerally not hot starts. Mentioned this to shop owner and he said this is most likely the resistor ends. For a fee, he could look at this and replace and bad ends. My only work around to this is to keep the RPM's above 1K until the engine smooths out.

Now before you comment let's go on to new problem #3. When coming to a medium to quick stop, something in my (and I think it's either the engine or transmission) VIBRATES and makes the car SHUDDER while stopping when the engine goes below 1k rpm. It even shakes for several seconds after stopping. The engine sounds like it's about to stall but it does not. This happens predictably. Mentioned this to the shop owner and he said the motor mounts were collapsed. Now here is an interesting observation, if I shift to neutral before braking, I can brake as hard and quick as I want with ABSOLUTELY NO idle roughness whatsoever. Behaves just like you would expect a mercedes to behave. I ruled out warped rotors because in neutral while braking problem disappears 100%

Now, I don't mind having the motor mounts, resistor ends and/or wires replaced, but, I wanted to get some expert opinions from the masters out here first, because I don't want to go in with 3 problems this time and come out with 9!

In summary I now have long cranking, rough idle (cold & warm), and vibration while/(and after) braking, except if I brake while transmission is in neutral.

What do you think is causing these 3 problems and why didn't I have these problems before I put my car in the shop?
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