5 replies to this topic

[Pete R]

Hi All :)

 

I have a bit of a problem, that is causing me to scratch my head a lot.

 

About 2 weeks ago i rather embarrassingly put about 7 litres of diesel in my 1985 Mini 25. Although it had the odd hicough and pop, it drove pretty much ok for 80 miles in four separate trips, with petrol top ups  to dilute the diesel. However, i then left it for a day. started it ok, but then after a couple of hundred yards, it was popping and banging so badly, that it was just totally undriveable

 

Hopefully somebody out there might be able to suggest something that i haven't tried, but at the moment all that happens is: I can start it when i take out the plugs and warm them with a heat gun before starting. Once it's going it's really rough and will only sort of tick over with my foot flat to the floor, no revving up past about 800 to 1000 RPM.

 

What I've done so far: Drained 25 litres of fuel out and replaced with 15 litres of fresh.

                                    Cleaned out float chamber and nylon tube to jet and the jet.

                                     Replaced the float chamber valve (it had worn shoulders on the valve)

                                     Replaced the main needle and made sure the jet was central and the piston drops with a "clonk"

                                     Made sure the jet is 1 to 2 mm below the bridge of the carb.

                                     Checked fuel flow from fuel pump by cranking the engine with the tube in a jar( 1 or 2 seconds half fills the jar)

                                     Gravity fed the float chamber.

 

                                    Checked points

                                    Replaced the spark plugs, leads and coil ( I now have the best spark I have had in 17 years it'll go like stink when it's fixed :) )

                                    Checked timing manually (Piston 1 TDC, Valves shut, Rotor on contact 1 on Dizzy)

                                    Tried moving timing slightly.

                                    

                                     Replaced head gasket and pulled all the valves whilst i was there and reground their seats.

                                     Checked and adjusted valve clearances.

 

                                    Turns out that some of the diesel had washed down the side of the rings and collected in the sump, so i changed the oil and filter also.

 

                                    Then I started looking for vacuum leaks with a can of easy start with no joy.

 

                                     Had the manifold off today and cleaned the faces and replaced the gaskets and smeared a bit of liquid gasket (High temp) on the faces and                                               gaskets.Also checked the small nozzle where the vac pipe from the ignition advance on the dizzy attaches. Tube also seems intact with no leaks.

 

 

Please can somebody help me :S

 

[nicklouse]

so what is the timing set at?

 

about 10 degrees static is a good start.

[Milton]

Diesel is a compression ignition fuel not a spark ignition fuel. If you have cleaned everything out then next thing is check your oil for petrol. Trying to compress diesel in a petrol engine can (not will) deform crank, cause rings to go, and cause damage to valves and stems. If you do find petrol in the oil then at least its new rings.

Check the oil level since you last changed it and see if it has risen.

[Pete R]

so what is the timing set at?

 

about 10 degrees static is a good start.

 

Not completely sure, but i would say a bit less than that, so it should start and run for sure without my foot flat.

 

Diesel is a compression ignition fuel not a spark ignition fuel. If you have cleaned everything out then next thing is check your oil for petrol. Trying to compress diesel in a petrol engine can (not will) deform crank, cause rings to go, and cause damage to valves and stems. If you do find petrol in the oil then at least its new rings.

Check the oil level since you last changed it and see if it has risen. 

 

Just been out and checked and the oil level is the same as when I changed it a few days ago. (I have been trying various things since, so I imagine the level would have gone up if fuel was making it's way past the rings, so hopefully they're ok )

[weef]

I take it that the engine was running fine before the misfuel?

If so it can be presumed that all the parts you have replaced etc were still serviceable as the fault persists. 

Go back to basics, checking all the serviceable adjustments are in spec, eg static timing, plug gaps, dwell angle, valve clearances, fuel filter,  oil and coolant levels and air cleaner condition. When satisfied all are correct carry out a compression check to see if there are any major differences that could lead to irregular running.

Next remove and drain the fuel tank, as it is the only way to ensure no contaminated fuel is left, flush with clean petrol, similarly flush the fuel line and the carb bowl.

With clean petrol in the tank you can now be sure that all is correct and apart from some fine tuning to the system when the engine is running and up to temperature.

I know this means back tracking on a lot of your work but you have to ensure the basics are correct before starting any fault finding..

 Please let me know how things progress.

[Rorf]

Did you do all these adjustments and engine work after the diesel mishap? Too many parameters have then been changed so difficult to identify the real problem. As mentioned you will have to start from basics - clean fuel and system, new spark plugs and set distributor timing up correctly. Try starting it up without the air filter on.

 

Might pay to do a compression test also.

 

Good luck