Hey Guys, my 87' 300E has a Hard start and the ABS light glows. At this point to start her, I need to push the gas petal just slightly to induce the start, if not she just cranks and cranks. It generally takes about 20 turnovers or 10 minutes to finally take off then were at a rough idle stage.... The strange thing is I replaced the alternator and battery and it ran Perfect for 2 days, firing up first crank without touching the gas, no ABS light either.
-The car has 188,000 mi.
-New Oxygen Sensor
-New Battery
-New Alternator
-New Starter
-The 10 amp fuse behind the battery checks OK.
-I've ran a bottle of fuel treatment through.
Did starting the car with my cell phone plugged in ruin my alternator? It was fine most of the summer.
Please help me out here gentlemen

 

had/have the same sort of problem on my 76 300D...

does the light turn off when the car is revved?
(mine you have to rev it a tad to shut off the light, revving spools up the alternator)
if so, you gotta shell out a small bit of cash (sorry to say this)
the cheapest way to attempt to correct it is new battery cables

(shouldnt be more than 20$ for some good ones)
on my car i had to really dig around in the enginecompartment to find all 3 connection places... if its hard to get at, get a cheap box end wrench, and lob the end off you dont need to make it short enough so you can use it...

but thats only if its hard to get at (if not just pop it off and put in a new one... remember to measure the wires with a peice of string or something flexibal)

if that does not fix it... you need a bigger battery (more ampearage)...
you get what you pay for in batterys, i went mantanance free on mine

but i went cheap on the battery, big mistake...
I dont have to rev it for more than like 1/2 second (verses about 2) to get the warning lights to turn off.
rule of thumb, YOU GET WHAT YOU PAY FOR, and buy something good or buy something twice...

feel free to pm me or e-mail me (92091236@students.ecasd.k12.wi.us)
Nathan

 

This sounds like the OVP relay (over voltage protection relay). It controls the ABS computer and the idle valve when cold. which is a major cause of hard starts. The fuse on top can be OK, but the welds inside the relay might need to be redone. This relay is also quite simple to replace either with a new MB one ($50 to $60) or to rebuild using Radio Shack components ($5 to $10). The diagram is on the service cd #1 under /electrical". Using both the diagram and the actual relay you can actually build a new relay using the old OVP board with the attached connector as a base. The main diode in the diagram is a zener diode 12 to 15 amps.
Hope this is helpfull,




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