CDR it gets rid of crankcase pressure and is part of emmisions. If you take the oiol fill cap off and it looks like an air compressor puffin away motor is probably tired but a well cared for 6.2 can last close to 400k miles. Missy did a write up of buying a used 6.5 in the 6.5 section. Most of the info there is useful for 6.2's as well except of course for the turbo and electronic IP stuff. Check the coolant for signs of contamination. 6.2's have dual exhaust so look at smoke from both tail pipes. Should be pretty even. If one side smokes any color more than the other could indicate a problem, see how it starts cold etc,. If you can bring it somewhere have the tranny checked out. TYhe Th700 1st gen which IIRC the 84's have were POS. They can be rebuilt to make them "better". If the truck has any starting issues and starting fliud has been used on it, tell em have a nice day and walk away. If the starter sounds excessively loud it could be a broken bolt or missing rear support bracket. Check the starter to make sure it has both bolts and rear support. Alot of guys have a broken bolt or cracked block from missing support or use of ether and then jerry rig the starter and sell it so check that out. It will usually sound really loud if that is the case. Not a whole lot goes wrong with these engines if they are treated right. They are actually quite reliable. The earlier ones the IPs used a plastic governor gear that goes but an IP for a 6.2 is cheap anyway.Expect to carry a spare alt belt. A gates 5725 is a good upgrade.
