I just had a pre-purchase inspection done on an 83 300D and the first thing they told me was the engine lacked adequate compression. Of the 5 cylinders the compression ranged from 195 - 220. The owner was supprised and I was disipointed because the car seems to crank easily on cold mornings and, according to the owner, cranked first time after sitting idle for 2 years. I've driven the car before and didn't notice any problems. The inspection was yesterday. Today, I found out that valve adjustment may be critical to accruate compressioin testing ( I'm not a mechanic, and don't know much about diesels). So, I called the shop where the inspection took place and asked if they checked the valves or adjusted the valves to insure proper clearance prior to testing compression. They said no, they do not do this. As a novice, my question is-----------will improper valve clearance/adjustment affect compression that much? I've been told that compression is 420 on these engines when new and in this 1983 car with 148k miles you should have a min. of 320. Otherwise, this is a very nice car and I'd like to buy it, but don't want to buy a sick engine. Any suggestions? Thanks for your help.