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Slightly exaggerated illustration...
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After my last flight (3 weeks ago) I had not only closed the
fuel tap on the firewall but also let the engine run dry.
Yesterday I went out to the field to prepare the plane for a longer flight next weekend, I removed the spark plugs to make sure they were clean, re-gap etc.
Yesterday I went out to the field to prepare the plane for a longer flight next weekend, I removed the spark plugs to make sure they were clean, re-gap etc.
2 spark plugs (one per cylinder) were overflowing with oil,
the 2 others just full of oil… I would not have been able to start.
While the fuel tap improves the situation it does not
eliminate the problem, nor does fuel tap and
running the engine dry...
So what about the quantity of oil? I have not measured the
quantity but estimate it to be a little less than a teaspoon – and I don’t know if
there is more oil in the engine… A teaspoon is 5 ml and with 2% oil this would
represent ¼ liter mixture, or the consumption for less than 1.5 minutes.
Knowing that similar problems on other engines have been
resolved by using longer spark plugs (to prevent the excess oil from running in
to the spark plug) I have asked Simonini for advice.
Fred, did you get any help from Simonini?
ReplyDeleteWhat brand oil do you use? Do you know the flash point? It may be worth trying a full synthetic with a low flash point like Amsoil Interceptor.
ReplyDeletewhat would be the difference?? It is a leakage no matter what oil is!
DeleteSorry, thought the leakage issue had been addressed and we might be dealing with unburned oil. You would be amazed what can survive the combustion process if you choose the wrong oil. Ask me how I know.
DeleteOn a Rotax 582, spark plugs are normally NGK B8Es or BR8ES.
ReplyDeleteBut on an inverted 582 a good advice is to use NGK BP8ES or BPR8ES, with an electrode a little bit much longer so that the firing cannot be under the oil level in the cylinders heads.
In fact when you fly very regularly (ie: once a week) no matter the kind of spark plugs. But if don't and let your engine sleep a lot, better use spark plugs with longer electrode.
I am trying the closed fuel tap before stopping but I am very sceptical, since the membranes behind the carburettors will prevent evaporate fuel into the engine itself. It rather will go out thru the air filters. But it improves a bit on the situation.
ReplyDeleteThe only thing which really helps starting without having the plugs pulled all the time after 2-3 weeks is full choke, no throttle, flood the engine with fresh petrol than, no choke, full open throttle to vent the fuel out. Than choke again with no throttle. But its eating the electric starter.
I think the only thing would really help is re-desing the cyl head with a deeper point where oil can gather and put the plugs into more aside of it. But its Simonini's work,...
Peter from Hungary
BPR9ES projected plug solves the problem !
ReplyDeleteAfter 2 weeks of standing, cranks like hell.
:)
Peter from Hungary