I've reposted this as it was hidden in my new member intro with a non descriptive title. I run various diesel vehicles and have just purchased a non running Polo 3 cylinder 1.4 AMF engined car. I have run bio in all of my vehicles since 2002 without problems. My first diesel vehicle was a Golf 1,5 in 1970 something which surprised me with a runaway on the highway without consequences. Since then it's been trucks and small marine engines through to medium GM marines to 2 x 2000 hp B&W's in a salvage tug where I was directly involved with service and maintenance. Currently running a 4wd VW Syncro with a Toyota 3ct td motor and an Opel light pick up with Isuzu TD power. Back to the start.......the Polo 1.4 appears to be 2/3 of a 1.9 PD motor and has a problem which I think I have pinpointed but won't be sure until I get the PD units to a service centre. I'ts a long story but goes roughly like this. Previous owner had the motor rebuilt (pistons, rings, bearings and head work but could not supply details). The vehicle was driven for around 1000km and then the performance dropped off rapidly to the point where it was towed home. This is where I bought it. The condition was declared by the seller so I had my eyes open and the price was right. The motor starts but there is an intermittent clatter and a brief attempt to run away accompanied by clouds of smoke. Turbo shows no sign of introducing oil into the system and there is almost no blow- by from the rocker oil filler. A process of elimination pointed to #1 PD unit. As I was testing and eliminating likely sources I started the motor with #1 glowplug removed and was a bit baffled by the colour of the fuel cloud blown out as it appeared to have a black tinge to it. I dismissed it and put it down to soot being washed off the piston etc. However I decide to drain the fuel filter into a container suspecting water contamination. There was no water but the fuel was black! Not printer ink black but black enough to be totally opaque in a 2L glass bottle. Also the fuel didn't smell like diesel but more like kerosene. I have drained the tanks and purged with bio. The misfire persists but now with no clatter and run away, probably because the bio is more resistant to igniting when not properly atomized. Liquid fuel which has accumulated in the exhaust poured out of the tail pipe when the motor was revved. The smoke on the suspected kerosene was very acrid and on the bio caused no discomfort. Cutting to the chase I suspect a service station is cutting their bunkers with kerosene and used engine oil. The previous owner is probably unaware as he would have been able to pinpoint his problem if he was the culprit. As it was the car stood for 6 months while he tried to repair it. This is where I am now and I''ll pull the PD units tomorrow. The black in the fuel has me thinking. If it's not used motor oil what could it be. The fuel has to be kerosene as the viscosity is very low and the smell is right. Is it possible that the "O" rings of the PD that seal in and separate the supply and return fuel have failed along with a poorly fitted PD unit allowing fuel to bypass the PD and enter the cylinder then be blown back into the return fuel channel on compression and thereby contaminating the fuel? Is anyone aware of leakage problems between "O" rings and the PD/combustion chamber seal? Update: I've found the problem............#1 PD has a fractured injector tip. It's a large piece as the photo shows. It's probably out of the cylinder by now and through the turbo and parked in the cat. Well I hope so. I still need to inspect the cylinder with a magnet and scope. There was undoubtedly reverse pumping back into the fuel circuit. Any ideas what causes this type of failure? My guess is an incorrectly set rocker adjuster but thinking about it afterwards the interconnecting parts aren't robust enough to do this damage. The fracture lines pass through two of the spray holes so it may well be due to erosion?