As the 616 and 617 diesel engines age, I am seeing an increasing number of worn out camshafts. In my humble opinion the cause of this is usually due to lack of frequent oil changes. Excessive valve clearance may also be a contributing element to the problem. It all begins with minor scoring of the cam lobes. Then over time the wear increases to scoring on the rocker arm and eventually the cam tip itself will wear to a sharp point. As this happens you will notice a gradual loss of power and the engine will begin to smoke more.
Problem & Solution
Common among these chassis:
WARNING: If you have just acquired a Mercedes diesel or you have a diesel that you've not personally removed the valve cover and inspected the camshaft, I suggest you do it now. In the case shown here, the camshaft was extremely worn (to a point!) and the engine was not developing good power. Once we replaced the cam and the rockers this particular turbo diesel engine came right back up to performance specs and at this time the engine has not developed any further problems. Buyer note: If you are in the process of looking to buy a used diesel Mercedes, I suggest this be one of your preliminary inspection items that you put high up on the check list. I often check the camshaft for wear when I go out and look at a used diesel to buy. In fact I put this inspection item right in the top three. The first thing I do is pull the air-cleaner cover and see how much oil is in the air filter housing and air filter itself. If I find an excessive amount of oil it gives me a good indication the engine is an oil burner. The second thing I do is a "blow-by" check by removing the breather tube from the valve cover and seeing just how much crank case vapor blow-by the engine is creating. Lots of blow-by could mean low compression and hard starting in the winter. The third top inspection item is to take off the oil filter cap on the valve cover and feel the top of the cam lobe with my finger. By running a finger nail across the cam lobe surface you can feel if there is excessive wear. If there is evidence of wear, then I ask to remove the valve cover for a thorough inspection before purchasing the vehicle.
If the camshaft is worn then it's a pretty good indication of very high mileage or poor maintenance over the life of the engine. Camshaft wear may indicate possible cylinder wall wear as well. Before purchasing the car have the engine compression tested. Camshaft replacement can be done without removing the chain or losing camshaft timing. New camshafts are not available. You will have to find a good used replacemnt
RECOMMENDATION: During inspection you should also perform a proper valve adjustment. If you are planning to remove and replace your camshaft, I recommend that you also replace the valve stem seals at the same time you change the cam. Please check out our related kits and instruction guides on replacing these items.