The W116 Library - The definitive W116 resource!

Main Menu

280SE stater motor problems

Started by Sluggish, 16 February 2024, 08:09 PM


Hey all

First time posting, but long time lurker. I really enjoy the imput on this site. I have an Australian 1977 280se.
My car had been sitting for some 37 years under a house. I purchased from original owner. I wanted to make sure the car run. I changed out the fuel etc and it did however I thought I must have burnt out the starter because I did wind over a fair bit using starter fluid to help get going. Since I have cleaned and replaced the fuel lines, injectors and serviced the fuel distributor.
I have also purchased a new Bosch stater motor and wired up.  However when I turn over all that happens is the fuel pump starts but nothing from the starter.
Is there a fuse or relay that I may have damaged when winding over previously or how do I test the trigger wire from the ignition?

Any help would be greatly appreciated


In the main fuse box in the engine compartment there should be 2x large relays.  They're called "ice cube relays" as they look like blocks of ice I suppose. One is for the fuel pump and one is for the starter.  Try swapping them out if you have a known good one as a test.

Should be circuit "4".

"21" is fuel pump relay.

Here is what they look like:
1977 450 SEL 6.9 - Astralsilber


What you described it's exactly what happens when one tries to start the engine with the gearbox lever in a position different than 'P' or 'N'.
If your lever is left in 'D' for example you hear only the pump running while the key is held in the 'start' position. That's perfectly normal. In fact we use that a lot as a technique when testing fuel system components to run the pump without letting the engine star. Much easier/safer than playing/jumping relays etc).
I'd say your wiring and relays are perfectly fine but you can always test the starter is getting 12V in the wires connection box right under the battery tray where the starter wires land at.
Perhaps while undoing those 3 bolts behind the starter you inadvertently touched the transmission rod or neutral safety switch (NSS) out of the ´P' position (?). Or your NSS itself is acting up, possible too. They're very easy to diagnose and repair. I'd play with the gearbox lever first while attempting to crank the engine and see what happens. Keep that key in 'start' and delicately move the lever up and down around 'P' or 'N'.

Please keep us posted.

Nice find by the way. After you deal with this starter situation, please share more details on the story and pictures of course.

Good luck



Firstly thank you for taking the time to reply. I have tried the relay switch before asking and unfortunately didn't make any difference. I have ordered two new ones for piece of mind.
I didn't about the linkage underneath, quite possible as I have changed all bushings in the front end and disrupted.
At next opportunity I will check out and let you know my findings.


One more thing you could do.
Check the engine oil.
High level? Smells gas? Low viscosity? Clear color?
You've mentioned pouring some to motivate the engine to start. Sometimes it could happen that we inadvertently throw too much, crank too much and overflow the chambers with gas. In extreme cases (I hope not yours) we can hydro block the engine. The symptoms are no starter noise, no cranking, but pump keeps making its noise throwing even more gas into the injectors when putting the key in start position. In other extreme/extreme cases we can bend a rod if we continue to try beyond those symptoms overheating/burning the starter even. Worth checking to rule that out too.



really simple fix, the gear selector had moved out of place. Once i readjusted it the car cranked over.

thanks for your help full suggestions!


Simple never fails.
Usual suspects (read statistically driven solutions paths) never let us down either when solving problems in our machines.
How about the history on that car? Pics?