Initial starting issue resolved by replacing bad fuse in ECU box, operated as designed for bit.

New starting issue is starter begins to engage but then stops, barely turning the engine. If the key is held in the 'start' position the starter will repeatedly and quite regularly (every 3-5 sec?) try to engage again.

The new battery exhibits 1100CCA at 12.8V and jumping the connections under the relay in the ECU box causes the starter to spin the engine enthusiastically. 'Jumping' with long trucker jumper-cables from the battery to engine compartment changes nothing. It's not the battery or connections.

There are no codes and every fuse I've been able to find on the car is OK.

I've swapped the relay in the ECU box with another, same symptoms.

I feel as though I've been beset by malicious fairies, so much for a holiday weekend! I've searched and haven't found anything like this, any thoughts???

What year car?

Does the car have a V6 M112 engine?

There is a service bulletin on that problem on a V6 M112 engine.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

'01 E320, US market car, 3.2 V-6, 4matic wagon. I think that's the M112 engine...

I've begun to wonder if the blown fuse was the beginning of the end of an ECU in the box, the ECU cooling fan that usually blows a fuse works fine, cycling on and off w/ ign. is on. But wouldn't a failed ECU throw some kind of code? I'm baffled with this one...

The issue is the starter to the flywheel.

Attached Files

Flywheel ring gear grease.pdf (60.4 KB, 211 views)

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Turned the engine by hand while lubing ring-gear w/ Fuchs heavy spray lube, then spun it with the starter by jumping relay connections in ECU box to make sure the lube is distributed but that didn't change anything. How much is too much lube on the ring gear? I'm having to apply it through the rubber-plugged hole on the bottom of the bellhousing as the starter on this 4matic car looks to be problematic to remove!

There's also a noticeable delay when turning the key to the 'start' position, like a ''one-thousand-one" pause before the starter cycle begins.

I give up, off to Hans und Fritz at the nearest dealer, 70 miles away, the first time since '03 or '04. I suspect it's the K40 and/or ECU and I hate to just start buying parts...

Investigated the K40 module: took the bottom cover off and the odor of burned electrics was strong, several solder joints on the bottom of the board had clearly been quite hot and at least two resistors on the board are cracked. Part arrives in the AM, I intend to say my prayers tonight...

UPDATE: Issue resolved, new K40 module has the Green Machine back on the road. It all seems obvious with 20/20 hindsight, blown fuse on K40 at first, then strange electrical symptoms. At least I didn't have to pay $250 towing and Lord knows how much at the dealer to figure this out. Thanks for the assistance, every suggestion helps!