Today I went to start my 1986 300E (gas)
I preformed the daily ritual of getting her started and warm before the trip to work. This ritual is somewhat tiresome but necessary as of now.
First, I turn the key to the ON position and wait until the buzzer stops then I return the ignition to the OFF position. I repeat this process two to four times depending on the time I’ve allotted myself to start and warm the 300E up before the trip to work.
This morning, I followed the normal routine it was somewhat different. When I started her up she cranked and cranked over but nothing happened.
I repeated all the steps from the beginning and still she just would crank and not fire over.

There were two different times this morning when I was trying to get her started that she sputtered and attempted to start but then, reverted back to just cranking.
This hard start has been a problem before; never like this though. I have been stuck in a parking lot 3 times last year about this time just cranking and cranking… the out of nowhere she fired up..

Does anyone have some insight on why this is happening?
I’m currently at the work place and my car is still in my driveway at home. This is an emergency.
Thanks,
Jon

1. Crank position sensor.

2. Fuel accumulator.

3. Fuel filter.

4. Fuel pump.

5...here is where it gets worse...fuel distributor.

But you did not mention, mileage, last tune up time and mileage, has it been pampered?

Good luck!

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I have never met a man so ignorant that I couldn't learn something from him. -Galileo Galilei, physicist and astronomer (1564-1642)

Need a bit more info:

When it does run, does it run well?

All that engine needs is spark, fuel, air, and vacuum to run.

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Eugene

10 E63 AMG
93 300te 4matic
07 BMW X3
14 Ford F-150 Fx2

first thing to check is spark-

get a known good spark plug, disconnect one of the ignition wires (that goes to one of the spark plugs on the car), attach it to the loose known good spark plug, ground the crown of the spark plug and check for a blue spark while an assistant cranks the car.

if you see spark they you have a different problem other than ignition.

Next thing to check is fuel. remove the fuel filler cap and put your ear next to it. Have an assistant turn the key to 'on' (don't crank). you should hear a 'hum' for a few seconds then it will stop. if you hear the hum then you are probably getting fuel. I say probably because you problem might still be fuel related but just downstream from the pump.

this might be the extent of any parking lot diagnosis at this point.

with the proper tools you can check for fuel flow to the injector rail. but I would start with the procedure above first.

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Ben
1987 190d 2.5Turbo

When she runs she runs well, when warmed up...
when I first get her started, I have to give it a few mins. because if i just take off i push on the gas and she seems to almost want to die before she will pick up speed.

Also has a low idle until warmed up


As for the maintenance I picked it up from the 2nd owner she gave it to me @ 124k last year about this time I just rolled over 130k this week.
I have service records that are up to date but i've been replacing things as needed to bring her back to her former glory... and so that i can be sure they where done...

Jon, if the engine has performed this way since you acquired the 1986 300E a year ago then it is a longterm problem. There should be no need to warm up the engine for several minutes before driving. The acceleration hesitation could be linked to a faulty Oxygen sensor.

If you're not an avid DIY'er you might consider taking your car to a reputable independent tech trained to work on MB automobiles. Otherwise follow Ben's advice to pinpoint the basic problem. Check the service records for replacement of the distributor cap, distributor rotor, spark plugs and ignition wires. They are all candidates for replacement if they haven't been changed within the last 30,000 miles. Once you get this underperforming engine sorted out you will feel like you're driving a different automobile.

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Fred Hoelzle

I have hooked up with someone in my area. He has a bobeyard of around 30 MB's ranging in years.
I am an advid DIY'er but the MB makes me uneasy. I love the car and don't know anything really about them.

VW = ME

Tonight I was on the phone with a local mechanic he said check spark and fuel like a few of you others did....

I have spark and I have fuel at the lines to the injectors.

I sat there and reved the engine and feathered it for about 20 mins until I was able to keep the rpms up to about 2-2500k for a few mins.

The Anti Lock light came on and the mechanic told me to check my OVP.

everything looked okay with the OVP but the fuse seemed to not be very tight.

I poped the top off of the relay, and squeezed the metal termanals down and re-assembled the relay.

The fuse I put back in was some what hard to insert and very firm to remove.

I put the OVP back into my 86 300e qnd it started better than it did before the problem started...

--------------------------------------- GUESS I GOT DAMN LUCKY -----

Thank you all for everything. I'm off to get some epoxy to make sure the top dosent pop off again.

Do you have any noticable loss in coolant or oil? Does it puff any kind of smoke out of the tailpipe or do you smell anything when warming it up? The head gaskets are notoriuous for leaking internally (oil seals also get hard and leak). It could be the warming up of the car might be the engine burning off the internal leaks in the leaky cylinders. The most improvement I had in starting and idle was after I replaced my O2 sensor. I tried the fuel accumulator idea as well and replaced the pumps and filter at the same time. Starting problem would still come and go. If it starts up pretty quick after you warm it up and then turn it off for a few minutes, then it could be the leakage. If it still has trouble starting and has to warm up, it probably has other issues as indicated by the other folks. Check the condition of your spark plugs and see if any look considerably different (worse) than the others. Unfortunately, if you don't get an expert W124 mechanic diagnosis, you may be tossing money at it until you eliminate the culprit.

Woops...did not see the last post. Glad it's better now. Another FYI just in case...in my daughter's '86, the fuel pump relays (ocated in the same area as the OVP behind the battery) were loose and after I tightened them down she stopped having issues with starting her car and it always idled and drove great. Best of luck!

I was bs'ing on the line while I was taking the fuel line loose he said that my year 300E (86') was nortorious for head gasket leaks...

When I pulled the spark plug the first 2 where a little wet...

That might be the next replacement

Valve stem seals may be leaking, its not a head gasket issue.
If there is no external loss of oil, and no oil in the coolant, the head gasket is fine.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

It was dark when i was messin with the car. I seen that the plugs where a little wet but i didnt get to take a good look..

like I said before Soon, she will be like brand new.... soon.