The head gasket of my Brother's car (21 year-old Peugeot 405) blew and it caused coolant to mix with oil. There is only coolant in oil but NO oil in coolant. Besides, combustion gases enter cooling system and pressurize it.
I'm preparing myself to remove the cylinder head to replace the gasket and probably resurface the head if need be.
However, I want to clean inside the engine to some extent before doing anything because I don't want to leave the block with oil/coolant mix on bearings and journals which may cause rust and corrosion.
Most people recommend draining the oil and fill it up with fresh new oil (and use a new oil filter), start the engine, let it run for a while and then drain it again and repeat the process 2 or 3 times.
My biggest problem here is if I drain and refill it with fresh oil and start the engine, coolant will again mix with oil due to failed gasket and I will be back to square one!
I can clean the head easily when I remove it from the car but cleaning the block is more important because I'm not going to disassemble it.
I was thinking about draining the coolant completely and then start the engine (stone cold engine) with fresh oil only for a few seconds (30 seconds or so) and do this several times to remove most of the coolant from oil passages. Will a stone cold engine still overheat if it only idles for a short period of time (less than a minute)?
After that, can I pour some diesel fuel through the dipstick tube (by the help of a hose) to fill the oil pan and let it sit there for a few hours and then drain it to clean the pan and the oil pump pickup tube? (Of course I'm not going to start the engine with diesel fuel in the oil pan!!)
