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Alan

Fuel Draining Jab 230c

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It looks like I am going to have to switch to using Mogas 95 in my Jab 230c as it is getting hard to conveniently access Avgas and I would rather operate on one or the other and not mix them.

Any tips for using Mogas? Anything to watch for apart from using a busy servo to ensure fresh fuel, being aware of vapour lock risk etc.

 

The Jabiru recommendation of not leaving Mogas in the tanks for longer than two weeks means more arduous use of the drain valves beyond checking for water.

How do others that use Mogas drain out the unused fuel ie. is there a standard drain hose fitting for the Jab fuel drain valves? 

 

Regards  

 

Alan

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It's worse if it's a 2 stroke  with premix.  Mogas Is not as reliable a product. When it goes off it really stinks sometimes if it gets a BUG in it. This also happens in AVTUR and they put a chemical in it to help prevent it. It blocks filters.. A recent largish lawnmower I purchased stipulates a "conditioner " for the fuel. it's a TORO . There might be something on line about it. I only advise you. I'm not taking any responsibility for it's safety.  2 weeks is not long ..  I wouldn't worry about a bit of avgas remaining in the tanks. It does mix OK but the Mogas degrades it (as you would expect) but it's still better than straight mogas. Nev

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I used to use Mogas 95 in my Jab 3300 engine but the quality of 95 is sometimes doubtful and some petrol stations no longer sell 95 & have gone to an Ethanol mix which is 94 RON. It has up to 10% ethanol in it. Do not use this. Ethanol is hygroscopic so it mixes with any water in the tank from condensation or whatever & reduces the amount of ethanol in the petrol while making the ethanol/water mix a much greater volume than if it was only water .

 

I now use exclusively 98 RON from a busy petrol station. My engine runs smoothly and I've never had an issue. It is also much cleaner than Avgas & doesn't foul plugs & leave deposits. There is a document put out by BP which discusses the issue of leaving fuel in storage tanks. Interestingly 98 RON increases its Octane rating over a period of 5 weeks but as the lighter components (aromatics like Toluene) evaporate off first the fuel becomes heavier so the mixture will be richer. It can cause problems in high revving conditions such as hard acceleration with a cold engine. This should never be the case with an aircraft engine if, as you should always do, warm it up to the minimums specified before a full power takeoff. 

 

You don't need to drain fuel out, just add some fresh fuel to what is already there & everything will be fine. The advice is to add some fresh if the engine is not run for more than a week. I usually fly at least once a weeks so it isn't an issue. A while ago after not flying for a couple of months due to weather and delays with parts I was quite surprised when I decided to test run the engine, it fired really quickly & I test flew it with no issues at all. Normally though I just add fresh fuel to the tank if I have not flown for some time.

 

The BP document is attached. It is 10 years old but the information is still current. There is a newer fact sheet with some of the same information but providing no technical explanations. It should have been titled "petrol use and storage for dummies"

petrol-life-vehicle-tanks.pdf

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I used Mogas in my Jab 2200 engine. It came from a busy caltex station, but i think the quality was dodgy as I had detonation. After fixing the piston and rings I went back to Avgas and no further problems.

I also used Mogas in the RV, but only for cruise where i could monitor what was happening. I got leaks around the rivets in the top of the tank. No leaks below the fuel level. I had to fix the leaking rivets using one of the thread locking chemicals. No further problems, but i won't try mogas again.

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I have about 350 hrs on 98 in my 2200. All good. I keep the tank half full and top up each time I fly with the amount I will need for the flight. Ken

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1 hour ago, Kenlsa said:

I have about 350 hrs on 98 in my 2200. All good. I keep the tank half full and top up each time I fly with the amount I will need for the flight. Ken

 

I manage fuel in the same way with my Jab 2200 (similar hours) and have had no issues to report. There is a second Jab in my hangar, does the same, and he doesnt have any probs either. Seems like 98 is OK for the 2200.

If I'm away for any length of time (more than 4 weeks), I try to use up as much fuel as is prudent, and when I fly next, put a large quantity of new fuel in both tanks, and make sure I give the engine a good warm up period.

 

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interesting topic.

Ive worked in the motorcycle industry for years. the engines being high performance are sensitive to fuel.

we steer clear of 98, it goes off too quick, usually sits in the servo tank longer, and is so full of additives/detergents that it causes rough running of bikes. (especially shell, our version of the IT turn it off and on again, is to drain the shell and refill with BP) 98 also causes cold starting issues.

 

recently we've had a bad run (think one a week) of bikes coming in with the tank rusted and the fuel pump destroyed from fuel sitting in tanks for 12 months. had one sit for 18 months and the fuel turned to a tar like substance, never seen it before. not like the old varnish you'd find in carbies

 

fuel has changed alot in the last 10 years, for starters there is no-longer any refineries in Australia

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Anyone who leaves fuel in a tank for a year or more & then tries to run the engine is an idiot. Even 91 will cause damage to a lawnmower engine if left that long. (98 that has been in the tank for 5 weeks or more will have most of the lighter components evaporated off and cold starting will be a major problem, if indeed it starts at all.

 

Loss of light components – impact on mixture
The light components in petrol are lost first as the petrol sits in the fuel tanks. These components provide valuable octane benefits during cold start. Because they are volatile they compose most of the air fuel mixture during cold start, if they are absent then the mixture becomes lean resulting in higher temperatures, pre ignition, detonation and piston damage. This is generally the cause of piston damage in high revving engines used in boats and small engines such as chain saws etc.
The portion of the petrol that remains has a higher density and higher octane but this is not available during cold start resulting in hard starting. Because the fuel carburetors and injectors operate on a volume metering system the higher density means that more fuel is introduced for a given volume of air and so the air fuel ratio is fuel rich. If all the fuel cannot be burnt then it forms carbon deposits that will foul the spark plug and cause the engine to stop and not start. This is generally the cause of problems in classic cars where the engine stumbles and hesitates or cuts out.

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yep, your not wrong. these bikes we pick up and service from storage before the owners use them again.

 

It used to be as simple as draining the fuel, blow the lines out, and filling with fresh stuff.

but currently the stuff is eating through tank linings and destroying fuel lines. never seen so much damage done so quickly.

used to be practice to store the tanks with a full tank of fuel in it to stop moisture build-up and rust. but these days its doing just as much if not more damage.

 

as for the carbon build-up,

that's what the old Italian tune-up is for
 

Edited by spenaroo

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On 2/18/2019 at 1:57 PM, spenaroo said:

......

 

fuel has changed alot in the last 10 years, for starters there is no-longer any refineries in Australia

 

I think we still have four refineries in Australia - at Altona Vic, Lytton Qld, Geelong Vic and Kwinana WA, producing about 55% of all the refined fuels we consume domestically. Australian Institute of Petroleum Factsheet 09/2017.

 

That was 2017, but is supported by the more recent July 2018 ABC update of the Australian Petroleum Stocks Fact Check.

 

I think Bulwer Island Qld was the last to close, in 2015. With each of the previous closures, the remaining refineries become a little more profitable -

 

Roger Montgomery - why our oil refineries are shutting down.

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There is also IOR (Inland Oil Refinery) at Eromanga QLD. They produce Avgas Petrol & Diesel & have a lot of truck stops.

Edited by kgwilson

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As the number of "Australian located " refineries has decreased the stored amount has reduced.  Our RESERVES are at a too low level as there's no money paid for doing it so it won't be done. Let alone issues with quality, that overall must be costing an absolute fortune. Nev

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