I have been making and using biodiesel for 7 years now, my quality is high, always >98% conversion, <200ppm of water and <60ppm of soap.
I have two Skoda Felicia cars, a hatchback and an estate. They have the 1.9 VW diesel in its simplest version, Rotary pump, no turbo, single camshaft, 2 valves per cylinder. They have run perfectly on B100 for 180,000 miles between them.
About 6 months ago the estate car broke down. The water pump failed causing the engine to overheat and damaging the head gasket. I had it towed home and replaced the waterpump and removed the cylinder head. I had the head skimmed, replaced the valve stem guides and also a couple of hydraulic tappets that were worn. I refitted the head with a new correct head gasket and replaced the timing belt while I was doing this. Ive done the timing belt on these cars before so I am confident it was done correctly. I also replaced the fuel filter.
When the repair was finished the engine was hard to start and ran very roughly with bluish white smoke when cold though once it is warm it ran perfectly.
I checked the heater plugs and sure enough one was faulty. After fitting a new one the engine started more easily but still ran very rough and smokey when cold. I removed the injectors and tested them with a pop tester and they are ok. I checked the timing and it is ok. The compression seems good and there is no smoke coming from either the oil filler cap or the dipstick tube. I have a short section of clear fuel hose on the injector pump and can see that the pump is receiving fuel with no air bubbles in it.
Last week my wife filled the tank with dinodiesel on a long trip and next morning the engine ran smoothly when cold. So the fuel is the problem but it wasnt before I did the work to the engine.
has anybody any ideas about this, it really has me stumped.
Don't personally have any experience with that engine, however may know what's happening.
The smoke sounds like low injector pressure, fuel is not atomizing correctly. Depending on how long you had it tore down, I've saw B100 get sticky in injectors, pumps, and fuel lines open to the air for much time.
I'd run it on dyno-diesel for a bit and check the fuel pressure if you can. If it's not a serous issue it will probably clean up after a tank or two. Since it was fine before you tore it down, sure sounds like oxidation of fuel causing ya issues.
You might be onto something there. The engine was unused for 6 months with B100 in the tank, I was just too busy to get the repair done. I will put a few tanks of dinodiesel through it and see if it solves the problem ( thats going to hurt, I have not bought diesel for several years !)I wonder if one of those injector cleaner additives would help?
I've tried Lucas, but after reading the label stating it's "biodegradable", felt it must be something close to biodiesel. Haven't notice any big improvements with any of the major fuel system cleaners.
In my case the engine was tore down for a year on B100. Ended up disassembling everything and soaking parts in Methanol just to get it running again.
My best suggestion at this point is run some K1 at high levels mixed with bio or dyno diesel and see how that does. Kerosene seems to clean the oxidized bio deposits as good as any special additive I've tested.
I think you are probably right about the additives. Here in Ireland kerosene is dyed red by the Customs and excise and you will be fined 2500euro if there are traces of that dye in your tank so I cant try the kerosene but I will run a few tanks of dino diesel through it. Thanks
How's that engine running now John?
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