Mercedes-Benz Forum - View Single Post - 1973 W115 timing and starting
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post #3 of Old 06-01-2012, 12:20 AM
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Originally Posted by GGE280 View Post
Hey DMon,
The problem you have could come from a number of issues. Please confirm that the primary issue began before you had the carburettor cleaned/set. i am also presuming you have the M115 motor - either a 200 or 230 4 cylinder.
Start with the easier problems. 1) Check your vacuum system carefully. The vacuum advance/retard hoses could be loose, leaking or possibly incorrectly fitted. There is a also a vacuum non-return valve on the primary hose between the Inlet manifold and the Brake booster housing, this could be faulty and contributing to faulty ignition advance/retard.
2) The ignition distributor shaft could be worn around the area of interface with ignition contact points, a visual inspection can show this.
3) I presume you are setting the timing using a strobe/timing light. If indeed you are seeing a significant variation of timing readings, then you probably have a major timing system fault. This can be caused by a sticking timing chain tensioner. This has to be removed and inspected manually, and invariably replaced if it is not operating freely. A faulty tensioner can cause damage to the chain system itself, so avoid over-revving the engine until this is resolved.
4) By removing the top/valve cover, you can inspect the camshaft gear for wear or any damage, but the more plausible suspect would be the intermediate gear which drives the ignition distributor and rotor. This could also be worn and introduce significant play which causes your timing to 'jump'.

I hope this helps,

Good luck
Some good advice there, the tensioner I would look closely at. I am not sure with this engine but there are two types of tensioner, one piece and two piece. With the two piece tensioner the outer case must be fitted first and the inner tensioner fitted after, if it is fitted as one piece then it can stick in the wide open position.


Last edited by eric242340; 06-01-2012 at 12:22 AM.
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