93 300e won't crank, need help diagnosing - PeachParts Mercedes-Benz Forum

darby · #1 03-04-2009, 12:12 AM

Initial problem: failed emissions testing yesterday, due to high hydrocarbons. Drove to local parts shop to get spark plugs, since I was told by emission shop that was the first thing to suspect.

As I got back in car to leave parts store.....car would not crank. Heard fuel pump run briefly and a single click from engine compartment, then nothing. Lights, radio, windows etc all work fine. I tried starting while jigling shifter all around neutral and park to no avail. Guy in store came out with portable battery jumper and tried that too..still nothing. I then figured the OVP relay had gone bad again, since this is how car acted about 4 years ago. So today I purchased a new OVP relay and put it in after work...still nothing (no crank, fuel pump runs, and only an occasional single click when turning key to start). I also had searched forum last night and had decided I would try jumping X27, as per Arthur Dalton's informative posts (hope you are reading Arthur!). But unlike the posts I read last night which all indicated starter engaged upon jumping 12V to middle terminal of x27 today, I got nothing. Only a small spark at terminal/jumper indicating I had current. I am now assuming I have a starter/solenoid problem.

I had to get the car towed back home tonight from auto parts store since I was unsuccessful in getting it started. And I really don't want to buy any more parts unnecessarily (I now have and extra non/refundable $60$ OVP relay). Any suggestions from anyone on how to procede? Arthur?

JonL · #2 03-04-2009, 01:05 AM

How easy is it to get at the starter on that car? Perhaps I should rephrase that... how difficult is it to get at the starter on that car? If you can get to the terminals at the starter, you can easily determine if the starter is the problem. (And it sounds like it is.)

Arthur Dalton · #3 03-04-2009, 09:00 AM

If you jumpered from bat + to center terminal of X27 w no crank, then the problem is at the starter/solinoid or a bad ground.[ assuming bat is up on charge]
Take a jumper cable and go from the bat - and go to a good engine ground
and retry with + to x27.

Also, take a good look at the wires going from the X27 to the starter [ behind oil filter]..common for those to have the same problem as the engine wire harness.

Suspect is starter.

Oracle12345 · #4 03-04-2009, 10:31 AM

hope this flow chart helps

Arthur Dalton · #5 03-04-2009, 10:37 AM

That is a RUN chart..he does not have CRANK.

And we know he has power to X27...so the problem is downstream from X27.

Oracle12345 · #6 03-04-2009, 10:50 AM

Quote:

Originally Posted by Arthur Dalton

That is a RUN chart..he does not have CRANK.

And we know he has power to X27...so the problem is downstream from X27.

it tells him the 3 major areas to check when the car dont start but doesnt give all things to consider ie bad battery etc

darby · #7 03-04-2009, 11:33 PM

Thanks for the responses. I tried the grounding jumper as you suggested Arthur, no effect. Lost daylight so no chance to check wires closely from x27 to starter. Priced rebuilt Bosch starter/solenoid today at $180. If I can't find fault in wires from x27 to starter guess I will move forward with replacing that. Anybody have replacement procedure for starter replacement on this rig?

Oracle12345 · #8 03-04-2009, 11:40 PM

Quote:

Originally Posted by darby

Thanks for the responses. I tried the grounding jumper as you suggested Arthur, no effect. Lost daylight so no chance to check wires closely from x27 to starter. Priced rebuilt Bosch starter/solenoid today at $180. If I can't find fault in wires from x27 to starter guess I will move forward with replacing that. Anybody have replacement procedure for starter replacement on this rig?

Download 15-7100.pdf from FileFactory.com

Download that file

Arthur Dalton · #9 03-04-2009, 11:55 PM

>

The top bolt takes a long extension [ I use a 20" and a 6" combined] and you get way back and sneek in over the top from the upper right side of the tranny.

If that harness is OK, then the suspect is sol or brushes...sometimes you can get a starter with hung up brushes to spin if you give it a smack while someome holds the key over..that will verify starter.

JonL · #10 03-05-2009, 12:01 AM

OK, let's be old school about this. First, confirm that your battery is good. Next, if you can get to the terminals on the starter... the big terminal connects directly to the battery positive terminal. You should have battery voltage here at all times. The small terminal energizes the solenoid when you turn the key to "start." Take a screwdriver. Use it to bridge the big terminal to the small terminal. If the starter cranks the engine, your starter is good. If it doesn't, your starter is bad. (Or your engine is seized, but we don't want to go there.) But be VERY careful not to touch the screwdriver to anything else when it is touching the main terminal!

Arthur Dalton · #11 03-05-2009, 12:06 AM

__________________
1987 W201 190D
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....and what do you think the X27 connection terminal does ???

JonL · #12 03-05-2009, 12:14 AM

Quote:

Originally Posted by Arthur Dalton

__________________
1987 W201 190D
>

....and what do you think the X27 connection terminal does ???

I think it adds another uncertainty to the procedure, as you said:

Quote:

Also, take a good look at the wires going from the X27 to the starter [ behind oil filter]..common for those to have the same problem as the engine wire harness.

Otherwise I think it's fine. Obviously easier, and if it cranks by jumping it there then there's no point in going to my suggestion.

Oracle12345 · #13 03-05-2009, 12:28 AM

whenever i have a starting problem i suspect fuel delivery, ignition and the starting circuit and elimnate anything that is fine. Check the obivous like fuses etc.

Just because the fuel pump can be heard working doesnt mean the system is up to pressure. I would take a quick fuel pressure test to verify if its working or not.

I would pull a spark plug and see how they look and inspect the ignition system. Also make sure the timing is right.

If these all checked out then I would starting elimnating components in thestarting circuit by making sure i have a good battery, do a few tests with a dvom to check the wiring, make sure the NSS is doing its job and then I would be left with the starter(ignition switch would be elimnated after 12volts was reaching the starter)

Kinda hard to diagnosis problems if you dont have the car in front of you

Arthur Dalton · #14 03-05-2009, 12:32 AM

Correct ... and that is why they put it there ...cuz you can't get to the wires at the starter on a 124.032 chassis car.
But you have a valid point and that is the old way we did it on an open engined compartment car/truck.
If you read his post, you will see that he has already done his homework and read one of the circuit tutorials I have in the Archieves on this exact chassis procedure ,,,that is how he knew about the X27 shortcut we use for diagnosis on this particular chassis.
The other VERY COMMON failure part on this exact chassis is they had a problem with the harness that went from the X27 test connector to the starter solinoid b/c of bio-degradable wire insulation...so, knowing that, one can see why my next recommendation step is to check that harness for that common complaint before changing the starter...he understands where the diagnostic stand and I credit him for using the Search feature of the Forum.
We are on the same page..and I am aware of this chassis circuity and it's common failures and weaknesses.............

Arthur Dalton · #15 03-05-2009, 12:39 AM

If these all checked out then I would starting elimnating components in thestarting circuit>

He has a NO CRANK condition.... I would certainly not be checking the timing and ignition system before I got the car to Crank....

Are we reading the same post??????????? Did you see his answers ????