Just bought an 86 F250 6.9 idi. It just had injectors (Stanadyne), glow plugs (no name) and return lines replaced and when the guy was test driving it, smoke started pouring out the exhaust. He told the owner it blew a head gasket and the owner did not want to put more money into it. Long story short I got the truck for $800 delivered and looking for some advice. I did a cold compression check - all cylinders are 300-400 psi. Pulled the CDR - packed full of a gray greasy substance. Inspected the check valve on the IP - clean but the gasket on compression fitting fell apart. There is a little bit of oil (could be diesel??) in the coolant and the rad is low but the bottle is full. I found two pieces of plastic when I pulled the CDR - 1 on the valley pan and 1 in the hole for the CDR - anyone know what these are??? Are they internal to the CDR? I think the smoke is fuel - doesn't smell sweet and is a bluish/white color. The truck fires right up but smokes a lot and based on the compression test I don't see that it could be a head (maybe more just hoping so). My plan is to pressure test the cooling system (need to rent the kit), replace glow plugs with motorcraft, replace injector return lines and o rings, possibly run a clear return and get rid of the metal tube, replace CDR and gaskets, replace FRAM fuel filter with Motorcraft and fill with diesel Kleen. Put it back together and see if there is any change. Would love to see the truck back on the road, thanks in advance for the help!