PeachParts Mercedes-Benz Forum - View Single Post

Tomguy · #13 04-21-2006, 03:33 PM

If this is like MANY other MBs of its time frame, and most other m116/m117 engines I've seen, getting those vacuum lines right is CRUCIAL to running right at every RPM - it will run rich at all RPMs if it's leaking, and it will show symptoms of low idle and possibly stalling. If I pull vac lines from my car while it's running, the idle drops a lot EXCEPT if I pull the one running to the distributor. ANY manifold vacuum leak will cause a lower idle. BEFORE adjusting the timing and everything, make 100% sure all your vac lines are connected, and connected PROPERLY. After doing that, check for vacuum leaks. The intake manifold is two halves, and the seals between them can crack over time and start to leak. Spray carb cleaner around it at idle and see if it sputters or stalls or changes the engine's tone at ALL. Do the same around the injectors and throttle body. Spraying anything on the outside of the intake areas should NOT change engine RPMs or tone, if it does, you have leaks!

AFTER (And only AFTER) you are sure EVERYTHING is hooked up right, you should set the timing. If your distributor's vacuum line is hooked up to the wrong source, or if your switch for it is bad, this WILL cause your timing to be WRONG so setting it before checking your vacuum lines is like balancing bald tires - A waste of time.

Get vacuum diagrams any way you can. Someone here has GOT to have them for you!