I just put the first 50 miles on my new '06 MXZ 500ss...it ran great but whenever I turned it off I heard a strange whining noise from under the hood like air was being forced out somewhere, which would go on for several minutes. After investigating for awhile I found that it stopped when I opened the gas cap, which released quite a bit of pressurized air. Anyone have any idea why it is doing this? The sound it makes almost sounds like a dying car horn. Is there a problem? Thanks for any help!

Mine doo it to. Don't tighten the cap too tight or it'll take all you got to get it off.

I have heard this is very common on the Rev's. Snowmutt said he actually heard the same thing on ours this past week but was aware to be listening for it from someones post on it over in Doo-talk. Most of the time it happens when you sit on the seat and the tank is full......and your right, it does sound like a dieing horn.

From what I have read, these sleds are equipped with a one way pressure relief valve so pressure does not build up in the gas tank.. That is what we are hearing.. No worries.

that's just the one way valve allowing air into the tank. i noticed it when i first got my sled and had a stroke worrying about my precious little yellow.

:withstupid:

Yes that is normal for the REV's. No worries :cool: .

:withstupid:

Yes that is normal for the REV's. No worries :cool: .
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Normal, but strange :dazed: Guess we are all the same when we get a new sled, listen for all the quirky things. I also heard it but had seen a thread on it so was prepared.

it is normal but keep an eye on it . my 2004 500ss they put the pressure valve in backwards and my tank colapsed down to 6 gallons . it has something to doo with the tank sitting on top of the heat exchanger

IT'S just gas pressure :blush: , just remember to say "EXCUSE ME" :lmao: .
I said that at a trailhead last wk , boy did i get a mixed reponse :whistling:. I almost blamed snow4 :devil: .

If anyone on the trail ask ,"what's that" just tell them the bee just buzzed his wings for pre flight. :wink:

Instead of just having an open vent line to atmosphere, there is a pressure relief valve in the vent line to keep a positive pressure in the tank. Since the tank is under your butt, this valve is intended to keep a positive or near zero pressure instead of a negative pressure when you get off the sled. Absolutely nothing to worry about.

also common on the machs.

My 05 MXZx 600 HO also had the Pressure valve installed Backwards also. It caused the tank to have a lot of vaccum in the tank. If installed correctly you should hear the wierd sound when you sit on the sled. I had an issue with the sled starving for fuel at one time after a long ride. Thought I was out of gas but I wasn't.