Help! 92 300E 2.6 died on way to work. - PeachParts Mercedes-Benz Forum

colingibb · #1 12-30-2005, 02:49 PM

I was making my regular commute to Atlanta this morning when my 300E quit on me. The car turns over normally but will not fire. I can hear the fuel pump powering up so I suspect the problem may be electrical. I had the car towed home and want to do some checks for fuel and spark. I think either the ignition control module or the coil are defective. Anyone out there had a similar problem or can suggest what I can try to troubleshoot the problem?
Thanks Colin Gibb

Sagittarius · #2 01-01-2006, 05:08 PM

My 420SEL has been doing the same thing. I had the fuel filter replaced but no luck. A MB mech told me it (definitely) was the Hydro Pneumatic Activator, a small black thing that sits under the air filter. ??? I can't find one but you might want to ask about this part.

John

softconsult · #3 01-01-2006, 07:54 PM

How's about telling us how many miles on the baby. Do you have the service records? Have the plugs been replaced? Distributor rotor and cap? What else has been done?

At about 175K my 1992 300E suddenly crapped out at a stop light 200 miles away from home in a rainstorm on a Sunday afternoon. Had it towed to a local MB Indy. He went through everything . We did EHA, Coil, OVP relay,
Plug Wires, O2 Sensor, and a few more things I don't remember. Granted I told him to make it right. $2500 worth of right. My point is that I wouldn't have stood a chance of getting it right.

Your situation may be different, but it's hard to guess when you provide almost no information .

Steve

suginami · #4 01-01-2006, 08:54 PM

Could be the OVP (over voltage protection relay).

Try a search for the above. There is tons and tons of info to read.

fahrgewehr2 · #5 01-01-2006, 09:15 PM

Don't see how the OVP could be the problem, as the car will run with it disconnected. Will be hard to start, though.

I think you are on the right track with ignition components, especially considering the car died in a rain storm.

lkchris · #6 01-01-2006, 09:53 PM

Still would look at fuel pump relay.

The device mechanic suggests is called electrohydraulic actuator (EHA), and it would be interesting to search this forum for descriptions of possible failure modes for this item. Only one I'm familiar with is that it can leak fuel, which doesn't mean car stops running.

When a motor suddenly stops running it's VERY likely not getting fuel and on this car it's very likely the fuel pump(s) and it's VERY likely they're not getting power.

Ignition systems on these cars are VERY powerful and VERY reliable and sudden failure seems unlikely.

Fuel pump relay failure happens a lot.

colingibb · #7 01-01-2006, 11:28 PM

Hi,
Thanks for all the great info. First of all, I was doing about 65 mph when the Merc died. It was a damp morning after a very heavy rain storm through the night. I had just serviced the car a week previously replacing spark plugs, plug wires, distributor cap ,rotor, oil, air and transmission filters (the fuel filter and O2 sensor about 3 months ago). The car has 217,000 miles on her and up to last Friday had never let me down.
I hooked up a timing light to the number 1 plug lead, pulled the trigger at the same time turning over the ignition. The strobe lit up. That makes me suspect the problem may now be fuel. I can hear the pump start up as normal and the fuel is reaching the fuel distribution block next to the throttle body.
Also, I have to admit it, a week earlier, I let the fuel level get down to reserve, something I usually never do. Is there a chance some crap got into the fuel system causing a block?
I'm going to take the spark plugs out to see how they look and also check the injectors to see if they spray fuel.
I'll get back to the forum and let you know what happens.
Thanks,
Colin.

fahrgewehr2 · #8 01-01-2006, 11:48 PM

Quote:

Originally Posted by lkchris

Still would look at fuel pump relay.

The device mechanic suggests is called electrohydraulic actuator (EHA), and it would be interesting to search this forum for descriptions of possible failure modes for this item. Only one I'm familiar with is that it can leak fuel, which doesn't mean car stops running.

When a motor suddenly stops running it's VERY likely not getting fuel and on this car it's very likely the fuel pump(s) and it's VERY likely they're not getting power.

Ignition systems on these cars are VERY powerful and VERY reliable and sudden failure seems unlikely.

Fuel pump relay failure happens a lot.

Your fuel pump relay is bundled with the MAS unit, near the fire wall, as opposed to earlier ('86-'89, I believe) models which had the individual relays.

colingibb · #9 01-03-2006, 09:17 AM

I just pulled all the spark plugs and found them to be black and sooty. I tested the number 1 plug wire with a plug in it and got spark when I turned the engine over. Am I right in assuming the car has a fuel problem?
Colin

Ferdman · #10 01-03-2006, 10:02 AM

Colin, black and sooty sparkplugs indicate too rich a fuel/air mixture, or oil bypassing the piston rings. Replace the sparkplugs with the proper type listed in the Owner's Manual and see how the engine runs. The spark you saw when testing the No. 1 sparkplug may not be strong enough to ignite the fuel/air mixture which would suggest that the coil is the culprit. What about trying a coil from another 300E to determine the condition of the coil?

colingibb · #11 01-03-2006, 10:26 AM

That's a good idea, Ferdman. I have a new coil coming and I will be buying new spark plugs and a fuel filter (cheap insurance)today. I'm sure you are right about the oil by-passing, the car is long overdue to have the valve stem oil seals replaced. I'm off the next couple of days. I will let you know what happens.
Thanks,
Colin.

Rob Pruijt · #12 01-03-2006, 10:43 AM

In diagnostics never assume, always check systematically.
The first thing I would check is the last one I repaired. Take off the distributor cap and check if everything is ok, all cables connected (check with Ohm meter) and if rotor is fixed properly. Don’t forget the black carbon pin that connects to the rotor. Failure of new components is not uncommon. If you have a bad connection somewhere you may still have a (weak) spark.
Once you are sure that the ignition is working perfectly , including timing, the next step is the fuel system. This procedure will save you a lot of money and time.

colingibb · #13 01-05-2006, 05:40 PM

Hi y'all,
Went back out and tried to get my 300E to run today. Put on a new coil and checked all the components I had recently fitted. Everything looks fine, but she still won't start.
Finally decided I will have to let the professionals look at it and had it towed to an independent Mercedes shop called Bridgeman Silver Star in Macon, GA.
First time in many years I have had to let someone else work on any of my cars. I don't want to keep throwing parts at it on the off chance I might get lucky.
While it's in the shop I have also asked them to replace the valve stem oil seals and do a wheel alignment. That should bring my car back up to snuff and be good to go for a while.Once they find out what the problem was I will get back to you all and let you know what transpired.
I would like to take this opportunity to thank everyone for their advice.
Colin

colingibb · #14 01-11-2006, 10:15 PM

Finally swallowed my pride and had my 300E to a local independent Mercedes shop in Macon, GA. Turns out the problem was the adaptor that connects the rotor to the front of the camshaft had broken.
I would have found that out if I had taken the cap fully off and examined the distributor more closely!
I also had them replace the valve stem oil seals as the car has been using a lot of oil. I will be monitoring the consumption to see how much difference this has made.
Had the shop check out the steering shake I had posted earlier. Advised all the suspension components were perfect and that I should have the tires electronically balanced on the car by someone like Butler Tire of Atlanta.
First time in many years I have had someone else work on any of my cars but it was money well spent. Anyone out there in Middle GA looking for a good Mercedes shop should try Bridgeman SilverStar in Macon. They were very courteous and helpful and had my baby back on the road in no time.
Also thanks to everyone who offered advice on previous posts.
Later y'all,
Colin.