Odd noise, need your help.

[subaru2006]

whats up guys. kinda need your help. my apex is making an odd noise. i would say it sounds like a thumper(motorcycle). just a quick run down i just got back from the UP without and problems. my last run there was across the lake varying throttle, when i parked it, it was fine. went and loaded sleds 20-30 minutes later it was fine. drove back to illinois where it sat for a day or so. unloaded the sled and it started making this noise.

as for modifications to the engine i really have none. i installed the oft racing rollover valve this past summer. i didn't roll it either lol. so that was the first thing i went to and checked out. im not sure but i don't think the valve is working properly. i say this because i don't hear it clicking open and closed. worked fine before.(so lets say some how it got stuck closed) *crankcase vent* could this cause damage to the sled? if so what?

next i went and checked the exhaust donuts hoping it was that. well they don't leak at all. not one bit.

lastly i havent pull the plugs to see if anything is going on there. but i figured i would come here to get some ideas.

as for the sound it only happens at idle and as it warms up it gets stronger. when riding it doesn't have any negative effects. no backfiring, no sputter, and full power no issues there.

here is the sound clip. the sound in the clip sounds worse than it really is. i placed my phone under the tunnel near the rear suspension.

http://s769.photobucket.com/albums/xx34 ... ysound.mp4


what do you guys think? or what should i look into to rule out?

thanks
subaru2006


edit: no check engine lights or codes. sled seems to run fine otherwise

 

[APEX 06]

Sounds like a exhaust leak.

 

[Blue Dave]

Plug the exhaust pipes with the engine running. If the engine doesn't die you have an exhaust leak somewhere.

 

[apron800]

agreed, exhaust leak, time to tear her down, cracked y pipe possibly, just tore one down sounded the same.

 

[subaru2006]

When i plug her up she doesent die. But slows way down. When i first fire the sled up it puts all that vapor out the exhaust(no not burnning anything) the normal stuff lol. I plug it up you would figure when i did that it would want to come out where ever the leak is correct? Well nothing is showing anywhere. Im gonna pull the plugs today and look.

Whats the easiest way to the exhaust? Seat down?

Subaru2006

 

[APEX 06]

Donuts- seat, tank

Exhuast-skid

 

[subaru2006]

well finally started to pull stuff apart seeing how winter never showed up... lol got seat/tank off and started her up to see what was leaking. sounds like the donut second from far right is leaking.. you guys were right.

will i have to pull the skid out, or can i undo from engine and flex joint and pull it apart?


thanks for the help. next question is were to buy new ones from?

subaru2006

 

[CaptCaper]

I pulled my skid out. I was able to work on the exhust system that way. Some guys here have left the exhust system in I believe but I too it out and got new pipe connector gaskets as well as donuts and Y pipes. If you look real close after you get the donuts and the ypipes out at the lip or flange of the Y pipe you might see chipped off sections and or cracking. Yami has SS pipes now that are susposed to be better holding up then the Ti ones that came oem.

 

[actionjack]

Hate to say it, mine sounded like that since I replaced the donuts. Ran fine all year, guess I m taking her apart again. Probably a flex pipe or the silencer gasket in my case.

 

[actionjack]

Hey how'd you test it withe tank off? Maybe just propped it up enough to see under the heat shield?

 

[subaru2006]

I havent been able to visually check it. But with the tank off i was able to turn it side ways and put an extended fuel line to it. From there i could hear the leak using this stethoscope thing my dad has. Worked like a charm.. soon as i pull it apart ill look at the pipes to make sure there are no cracks. I caught this early so im hoping nothing else is wrong.

Subaru2006