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Viton tips & Ethanol etc.

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Blumax008(at)aol.com
Guest

Posted: Sun Nov 22, 2009 12:05 pm Post subject: Viton tips & Ethanol etc.

I got the following (in red) from Ask.com. Bear in mind that it  relates to Ethanol used in Automobiles...not 2-cycle Rotax engines. With that in  mind, does anyone know if Ethanol will affect the rubber (neoprene?)  Viton tip used on the float needle valve in a Rotax carb?

  

 Also, is the Viton tip made of rubber or neoprene?

  

 Lost 90% power the other day due to fuel starvation in one carb (dual carb  503). The float bowl was flooding previously (overflowing thru vent tube) but  was still performing normally. When it lost power on a later flight (which  resulted in an off airport landing), the same float bowl was empty. An  A&I mechanic said that the Viton tip could stick both ways causing fuel  overflow & fuel starvation. I disassembled the float needle  valve & Viton tip & found that the Viton tip had some  deterioration but am not sure this caused the sticking. Has anyone ever  experienced anything like this?

  

  

 A 10% blend of ethanol and gasoline will not harm any  engine or fuel system component. However, the ethanol has a cleaning effect that  will remove rust and other junk from the fuel system. This necessitates frequent  fuel filter changes until the fuel system is cleaned out.  

No modifications need to be done to  allow an engine to run on a 10% blend of ethanol and gasoline. There is, in some  areas, an 85% blend of ethanol and gasoline that does require engine  modifications. 

Actually there is no rubber used in the  fuel system. All the fuel lines are made of Neoprene which is impervious to  degradation by gasoline or other additives.

  

  [quote][b]

rampil

Joined: 04 May 2007
Posts: 870

Posted: Sun Nov 22, 2009 2:33 pm Post subject: Re: Viton tips & Ethanol etc.

Viton is a mixture of synthetic rubber and fluorocarbon polymer



it is neither rubber nor neoprene.



it comes in many variants and some are sensitive to organic

solvents like ethanol.



So far as I know, nothing in the rotax engine family is sensitive to

ethanol

_________________
Ira N224XS

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Sun Nov 22, 2009 3:29 pm Post subject: Re: Viton tips & Ethanol etc.

Rampil is right, nothing in the carb should be an issue for the 10% or less ethanol. There was an SB out for some of the older float needles. If you have an engine over approx. 5-6 years old the SB might pertain to you. You will need to look this up because I can't remember off the top of my head where the cut off was. The float needles have springs in them and they wear out. The old Viton tipped needle was red and the new ones are black. Plus there were a couple of other colors that had different spring pressures. Make sure your up to date on the right needle valve and make sure it is not just plain old and worn out. If you have a float needle older than 3 years old it should be replaced any way because it is getting old and worn. Many parts should not just wear out and quit before replacement. They have a timed life and these parts should be thrown away. Rotax wants all rubber parts replaced regardless of hours every 5 years. Rubber gets hard and may break or break down inside and get places you don't want it to go.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

Tom463(at)aol.com
Guest

Posted: Sun Nov 22, 2009 4:02 pm Post subject: Viton tips & Ethanol etc.

I just had the 200 hour service done on my 1 year old 912S. I always used  93 Octane auto gas.  Non-Ethanol auto gas is no longer available in this  area.

  

 The floats in the carburetors were found to be detoriating and flakes large  enough to clog the main jet were about to separate.  It is possible the  floats were from a bad batch of resin; however, the Rotax Service Center  believed the cause was Ethanol in the gas.

  

 They showed me a carburetor float bowl with corrision in the bottom of the  bowl.  It was from a 200 hour, 5 year old 912S.  Also, attributed to  Ethanol fuel and infrequent flying.

  

 I'll be using 100LL from now on.

  

 Tom Yowell

 N569AT

  [quote][b]

rampil

Joined: 04 May 2007
Posts: 870

Posted: Sun Nov 22, 2009 6:32 pm Post subject: Re: Viton tips & Ethanol etc.

Tom,



Just out of curiosity, which Rotax Service center did you have 

work on your engine.  I have been using Mogas for 5.5 years

about 275 hours.  I have not seen any deterioration of any parts

(except my first muffler which cracked in several places).

_________________
Ira N224XS

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Sun Nov 22, 2009 6:45 pm Post subject: Re: Viton tips & Ethanol etc.

I have seen a few floats flake, but usually older floats. A few new ones. I service lots of planes and almost all use ethanol and none have any issues. You add all these guys total hours and were talking tens of thousands of hours and no problems. The planes that are at least 4-5 years old ought to have the floats changed out and not just because of ethanol, but age.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

ami(at)mcfadyean.freeserv
Guest

Posted: Mon Nov 23, 2009 1:13 am Post subject: Viton tips & Ethanol etc.

Viton is made of Viton (a fluoroelastomer) which has excellent resistance  to alcohol, as does neoprene.

 However, the latter has poor resistance to the aromatics in 'high octane'  fuels (eg super-unleaded).

  

 Duncan McF.

 [quote]   ---

Tom463(at)aol.com
Guest

Posted: Mon Nov 23, 2009 3:36 am Post subject: Viton tips & Ethanol etc.

Lockwood Aviation, Sebring, Fl

  [quote][b]

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Mon Nov 23, 2009 5:11 am Post subject: Re: Viton tips & Ethanol etc.

I've become a 10% believer myself since the SB approving 10% finally came out this past summer. Switched to it the next day and have had no issues that I've been able to see in my 912.

When I bought my plane a couple years ago, the bottoms of the bowls did have a scaley buildup. But I've seen that so much with my other engines, namely my 2-strokes, that I don't even think anything of it anymore. When it starts to build up I simply dremel it out with a wire brush and carefully clean it all up, blow it out with compressed air etc. 

I don't think that has anything to do with 10% and for all I know the 10% probably helps keep everything clean in the system .



I kept an eagle eye out on my fuel filter and fuel lines for the first several tanks after the switch, but had zero problems. 



As for 100LL, a friend of mine ran almost all 100LL through his 912uls for quite a long time, even using full synthetic oil (Mobile 1). After a couple oil changes he pulled his oil tank and found no sludge buildup whatsoever. All he needed to do was wipe a little film off the bottom of the tank and that was it. Er, maybe it was just leaving all the sludge in the motor 

Course I wouldn't necessarily recommend deviating from the rotax maintenance schedule for 100LL based on that, but it was pretty interesting to me. 



LS

_________________
LS
Titan II SS

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Mon Nov 23, 2009 7:11 am Post subject: Re: Viton tips & Ethanol etc.

Your friend wouldn't see anything in the full synthetic oil any way and it would be very misleading as to what was going on inside the engine. The 100LL would only leave a grey paste type substance on the bottom of the tank. If your friend continues with the full synthetic and 100LL he is headed for one expensive fix. His clutch will get clogged sooner, too.



100LL won't leave a sludge. It will leave over time regardless of the oil a grey film on the bottom of the oil tank. This is the lead falling out of solution and building up in the bottom of the tank. It will do this in your gearbox and crankcase too. The full synthetic oil will not suspend the lead at all and it will fall out in greater qualities compared to semi synthetic and full dino based oils. At the 800 hr mark you ought to see the grey lead build up in your gearbox clutch. If not removed it will keep the clutch from functioning. If you can use 91 Oct. you are better off if not then use the fuel additive Decalin. You can get it from Aircraft Spruce. Use it at 1/2 oz. per 10 gals. of 100LL. This additive won't help the oil, but will help keep it out of the fuel burning areas. TCP is no longer approved for a Rotax engine and Rotax has advised people to stop using it. They are now finding problems with people who have used TCP.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

Blumax008(at)aol.com
Guest

Posted: Mon Nov 23, 2009 7:49 am Post subject: Viton tips & Ethanol etc.

In a message dated 11/22/2009 5:34:40 P.M. Eastern Standard Time,  ira.rampil(at)gmail.com writes:

  	  Quote: 	
		  Viton is    a mixture of synthetic rubber and fluorocarbon polymer



it is neither    rubber nor neoprene.

	


 

 Nothing like posting a question, then getting a reply & feeling stupid.  So Viton is neither rubber nor neoprene! Thanks for that. Had no ideee!  Thanks to all who answered.

  

 An excelllent 2-sicle mechanic friend of mine says there's a  possibility that the Viton tip could be swelling on me. Good thought. Does  anyone know if this could be true?

  

 The reason that he & I think it could be true is that I had a Phantom  that was overheating like hell on me. After going thru jet cleanings & jet  changes to no avail, I had him send me two carbs which I exchanged onto the  Trike. It cured the problem immediately. I sent him the old carbs which he tore  down & couldn't find a thing wrong with them. The only thing he can figure  is...Viton tip swelling...which would also explain the fuel overflow /  starvation problem I had on my Trike a few days ago.

  

 The problem is that I've been flying these contraptions for a very long  time. I mostly left my old Trike in my front yard for years...like 12 years,  flew it often but it never gave me a problem...especially a carb  problem. NOW, since I've been using Ethanol laced fuel for the past few  months, I've had nothing but carb problems. Are my carbs haunted since we just  passed Halloween or does Ethanol have more to do with it than I  think?

  [quote][b]

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