1972 Mercedes Benz 280SE 4.5 Distributor & Trigger Points Removal & Cleaning

I inspect and clean the distributor cap & rotor. Next, I take out the distributor and remove the trigger points for inspection and cleaning. I then test the vacuum advance mechanism. After reinstallation I reset the timing and idle speed on my 1972 Mercedes Benz 280SE 4.5 with Bosch D-Jetronic electronic fuel injection. Video made on May 10, 2022.

[@michaelsliwinski8044]

thank you for sharing!

[@kensshowtell]

My pleasure. Thank you for watching.

[@R107Schrauber]

Thank you for this video

[@kensshowtell]

Thank you for watching. I learned a lot in the process.

[@martinowens5309]

Hi Ken. Watched with great interest. I have a 1972 R107 350SL. The engine looks nearly identical. It sat for 20 years and I just started. Replaced fuel system including injectors, ignition wires, plugs, cap, and installed electronic ignition optical FAST X700. It worked except the tach now reads 4500 for a true 800 rpm… got to figure that one out. It started first time and sounded good at idle and accelerating in park. Took for its maiden voyage up the road. It bogs down and misfires. I am guessing it needs timing and your video is the only one I found that comes close. The setting I found on the internet is 5A TDC at 800 rpm which was curiously different from yours but I suppose ok. I’m going to by a timing light this weekend. I had one 40 years ago when I had a 1970 OPEL GT.

[@kensshowtell]

Thank you for watching and commenting. Your engine is the M116 and mine is the M117. The M116 is a high compression (9.5 to 1) 3.5-liter V-8 whereas the M117 is a 4.5-liter low compression V-8. They produce similar horsepower. However, yours requires at least 93 octane fuel and is higher revving whereas mine does well on 87 or 89 octane and is low revving. The timing requirements are quite different between the engines because mine has longer stroke and is "lazier" than yours. They have the same Bosch D-Jetronic fuel injection system. Backfiring usually is an ignition issue. If you have not pulled the distributor, you might consider doing so in order to clean the trigger points deep within the distributor as they help the ECU time when and how long the injectors squirt fuel.

[@tonyreyes9969]

If my memory serves me right the vacuum mechanism used on this particular model retards the the ignition timing when in operation.

[@kensshowtell]

Thank you for watching and taking your time to comment. My understanding is that the vacuum mechanism places the ignition timing in the correct state of advance as the engine accelerates. This is one reason for pre-detonation (pinging) if the distributor is set to far in advance to begin with. It is also a reason for sluggish engine performance if the distributor is set to far behind (retardation) to begin with.