300E Problems

Hello: Happy New Year everyone.....

Today while driving my 300E. M103, the check engine light came on. This evening while drving for about 2 minutes the car decided to go on vacation and stop running. Thankfully were were able to use a rope and pull the car to safety at my local volunteer rescue station, which I am a member of. After the car sits for a while it will start and run normal for about 30 seconds then quit. In the past couple years many parts have been replaced. I would appreciate any help with this problem. Thank you- Charlie, 140,000 miles 300E 1989

Reply to
Chuckyg
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Suggestions:

  1. Fuel Filter - Engine runs briefly and quits. Fuel starvation.

  1. Fuel Pump Relay - Intermittent relay drops power to fuel pump.

Reply to
T.G. Lambach

Hi Tom.....Thanks for your prompt response....I know that everyones time is very important. Could that make the check engine light come on? I always thought that on these older models it takes an "Act of God" for that light to appear....The pump relay is brandy new. When i turn the key, the pump sounds strong before cranking over. I was able to get the car home a few minutes ago and it rode fine home, about one mile. My sister has been driving it for a while at school. The car really hasn't been under a tremendous load.....However, it's a car and is to be drivin. Thanks for the help so far- Charlie-Monmouth County NJ

Reply to
Chuckyg

I would have suspected fuel pump relay too... Sounds exactly like it. Where did you get it? New or remanufactured?

I would also check the overload relay.

Last thing I can think of is the distributor cap and rotor.

Reply to
Tiger

Tiger, it all comes back to me - this guy lent his car to a relative. She let the battery go down and some well meaning idiot jumped the dead battery but REVERSED the polarity. So Chuck spent buko $$ on parts to fix the mess, including an OVP relay.

Lots of stuff was replaced and it finally seemed to be OK back in November.

Now this.

Until some further data is available I still vote "fuel filter" or, given that it's winter, water in the fuel line that freezes and so blocks the fuel supply. Add "DryGas" or equivalent to fuel.

Tom

Reply to
T.G. Lambach

Mmm... that is quite a fiasco... I don't see how reversing a polarity will burn out anything but the OVP fuse. That is what this is designed for.

I remember a cracked distributor cap will do the same thing.

Another possibility is crank position sensor... if this is shot, engine won't run either. But this is a rare part to replace on any Mercedes... BMW is very common... but not Mercedes.

Reply to
Tiger

I think your correct Tom. The fuel filter has never been replaced on this car. -Chuck

Reply to
Chuckyg

check your distributor rotor adaptor plate. Its a disc that attaches to the end of the camshaft. Believe it or not, Ive heard they break....

-- dave_rose69

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Reply to
dave_rose69

Hi Can someone please help me with my 300E diesel, my battery keeps going flat, have tested for alternator is charging when car is hot or cold and is fine. I have put a new battery on her but still have problems. I have checked main fuses, any advice would be appreciated thanks,

Reply to
sprayer

There are many causes to your condition. Shorted diode in alternator, bad voltage regulator, (most alternaters have them integrated within the alternator itself), or something is staying "on" in your electrical system, thus drawing the battery down. If you have a new battery to start with, then use a good VOM meter and check your charge back voltage when the engine is running. It shout read at least 13.5 volts or more. If it does, slowly add accessories to add to the load. First headlights, then blower and rear defroster, radio, wipers etc. The voltage shoud not drop past 13.0 volts. If after a few items turned on and the voltage drops below 12.8 or so volts, your alternator and or regulator is failing. If the voltage holds well at or above 13 volts when things are on, something is drawing power from the battery during the engine ignition off condition. In a darkened area, and make sure all doors are closed, no key in ignition, disconnect the negative side of the battery, and stroke it against the same neg terminal and watch for small sparks. (wear safety glasses) You might get a tiny one at first but then see nothing after. This is normal. If you constantly see small sparks coming fron this swiping action, you have a drain somewhere. Pulling one fuse at a time can help locate which device is pulling power, but unless your a seasoned electrical trouble shooter, bring it to a sharp electrical guy, to find exactly whats pulling your power away. Buy a special terminal cleaner tool, (round wire brush type), and clean your terminal clamps and battery posts shinny. Also check the belt tension on the alternator. The whole problem might be corroded terminals.....

-- dave_rose69

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Reply to
dave_rose69

Have you had the battery load tested? That is so you know if it's any good? how old is it?

How many volts is the alternator supplying the battery with?

Reply to
Richard Sexton

If you got new battery, then you need a new alternator.even though you think it is charging... chargine is 14.4V... anything lower than 13.4 will not charge.

Reply to
Tiger

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