Valve Adjustment 617: What Are Symptoms It's Needed?
 

Done some searches....couldn't really find anything.

I'm thinking about picking up an 85 300D. I know the valves are supposed to be adjusted every 15,000 miles or so. What I'm wondering: are there particular symptoms that indicate the valves need to be adjusted? If so, what are they?

Thanks.

some of the symptoms include..

Low Compression
hard starting
smoking from unburnt diesel not getting a clean burn
loss of power and fuel economy

Just a few

Symptoms are not knowing when they were last checked or if fifteen thousand miles have elapsed since the last check.

Not common on the diesels but you can damage the face of the valves by not doing it. On the older mercedes gas engines it was common to burn exhaust valves by not checking them when due.

Another symptom - when you first start it, you have to keep it rev'd up a bit or it will die. Example - I used to have to sprint in reverse out of my garage in the mornings or else it would cough and die. After I had the valves adjusted, I could just glide out of the garage. So it is running much smoother when cold now that the valves are adjusted.