I have a cold start issue that has become progressively worse. My car is currently in for service. The shop (dealer) first checked glow pugs as I would have suggested. The resistance test was good for all glow plugs.

Next was a valve adjustment and had minimal effect. They then proceeded to test the injectors and reported that they looked perfectly clean, tested OK.

Could a glow plug have the correct resistance and not produce enough heat?

Any thoughts on other potential issues?

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2012 B Class

1981 300D - Now with greazzer