Is Crank Bearing Failure Common?


BETHEVIPER said:
so your going to stand by the statement that a plastic 12 gallon tank, vented to atmosphere, empty, in a constantly changing temperature is not going to breath????? It is all about lessening the amount of air exchanging into the tank as well as the other side.

The other side is, gas that is dried onto the inside of your tank and inside of your pump and fuel lines leaves a mineral residue, this residue is washed off and mixed with the new gas as sediment, to either go through the carbs or to stick in the filter. If the tank, fuel lines, pump and carbs are filled, there is less of this mix with new gas. Carbs will evaporate a litte through the storage and need to be cleaned anyway.
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You’re right that I should not have said NO breathing takes place with an empty tank (a previously fuel exposed tank). But compared to a full tank; or worse a half tank, the level of breathing isn’t comparable. Unless you can completely fill up the vapor space (to the point of overflow during expansion), you’re still going to have ingress of moisture laden atmosphere - that’s exposed to liquid fuel that is more than likely to contain moisture sucking ethanol. Also, the inside tank temp will follow the changes in ambient temps more quickly if empty since it doesn't have a large heat sink (the fuel). The differences in the bulk fuel temp vs. ambient is what causes most of the breathing even with a small vapor space. The larger the difference the greater the breathing.

From what I’ve gathered, that’s the reason why most manufactures have recommended draining for storage. The Stihl farm boss I bought last year, Husqy weedwacker and '01 SRX owner's guide ( a suppliment, not the printed book) all recommend draining. I have a scanned PDF of the storage recommendation from Yamaha Service if anyone is interested.


I agree that with gasoline of old (even un-treated), storing with a full tank is fine. In fact, it’s best to have some fuel in a plastic tank for long term storage to keep the hydrocarbons that replaced the plastisizers from leaching back out of the tank skin.

I think aviation fuel is exempt from the ethanol mandate. If I'm not mistaken, most airplanes have thier tanks within the wing so they're flat, long and shallow. With so much surface area the fuel heats and cools quickly thus creating a lot of breathing especially if stored outside. I would imagine a water seperator or low-spot tank drain is essential on an aircraft.

I agree that the residue left from the dried fuel is a concern but I don't think it out-weighs the issues ethanol creates. Me personally - after I drain the fuel from the tank, I add a half gallon or so of pre-mix and run it through the system, drain it, then run the sled 'til it dies. With fogging oil in hand, I full choke it to get it lit than poor the fogging oil to it until the can is empty.

I like to think the oil from the pre-mix protects the pump diaphrams, fuel lines and such but I have no data to back that up. I think there is something to be said about Gary Nos' suggestion of using trans fluid for fogging although I'm not convinced that it protects the bottom end but I'm sure it treats the lines and rubber real nice. Maybe some type F instead of 2 cycle oil is the way to go.

Since you also recommend draining and filling with fresh fuel before the first ride (after carb cleaning) it probably doesn't make much of a difference either way. And for long term storage (longer than a summer - like me this year, I never took it off the stand) having fuel in the tank helps keep the tank ply-able.

Finally, another less important reason I drain is that I'm not comfortable having 12 gallons of fuel sitting in a vented tank.

Anyhow, that's my opinion and you know what they say about those. I'll go back to polishing my... er, um, clutches.
 
davidgboy said:
bottom line: for most situations- fog engine- make decision on fuel system. dont forget about the damn rodents.(if sled in vulnerable enviroment) at least remove air filter and stuff some rags in box. u should open hood fairly often to make sure they dont go to town on ya.
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those rags you leave in there should make for a nice mouse nest ;):D
 
I use the tennis ball or steel wool in the exhaust opening to seal off.For the carbs you could just take abs pipe with cap on it,slide the open end into the reed rubber opening and tighten clamps.
 
I have a pit bull on patrol, seriously! She is a better mouser than any cat I have ever seen. We had these ground squirrel things emphasis on HAD. Bought a pop up 2 years ago that HAD micce in it. She would lay on the deck and watch it like a hawk...then BOOM! off like a rocket. Before her I would use moth balls (ever try catching a moth?) and fabric softner sheets.
 
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