<VV> RE: VirtualVairs Digest, Vol 3, Issue 184

[Tony Underwood]

Gas in the oil?




>a) carburettor needle valve (we've checked that - it isn't that, and anyway,
>
>carb is new)
>
>b) fuel getting past the pistons and into the pan, if one or more cylinders
>have broken rings - we have checked the compressions and they are all
>normal, and there is no blow-by (always a problem on these engines if a ring
>
>goes - they begin to smoke a lot into the engine compartment, and this one
>isn't doing). We haven't done a leakdown text yet, but we will soon. I don't
>
>think this is the problem, though, although it does have a very slight
>misfire, that clears itself over about 2000 revs.
>
>c) fuel pump diaphragm failed and leaking fuel into engine a la Corvair -
>it's not that because there is no path for the fuel to follow through into
>the pan with the pump on this engine.


How is the fuel pump actuated?   If there's a mechanical connection to the 
inside of the engine I'd suspect it.



>So... we have investigated all three possible causes that we know of, and it
>
>doesn't appear to be any of them! Does anyone know of a fourth, before I
>ruin my engine? I am now taking the car off the road until I fix the
>problem, because it will undoubtedly trash the engine if I carry on driving
>it with thin oil mixed with gasoline!


Is this car parked with the tank end higher than the engine end?

Fuel *can* siphon into the engine if there's any sort of leak in the pump 
circuit if the tank is higher than the engine/carb/pump/whatever.    Been 
there done that with a fuel pump with leaky diaphragm.



tony..