Knocking noise in motor

[powder_bound]

Hi all newbie here… thanks in advance,

Just bought a 2002 800 edge, had 1300 hundred miles on it. I’m noticing a knocking sound after motor comes up to temp on PTO side. Seems to happen when I rev about 2500 rpm then stops as I pass that. When I throttle down happens again at 2500 rpm. Doesn’t happen when motor is cold and I’m pretty sue its not coming from Primary clutch but Im going to pull it off and try it. PTO side crank bearing going out? Ideas?

Thanks

 

[winter brew]

rod bearing.....knocking noises are never good.

 

[powder_bound]

Thanks Winter Brew, guess I'll tear the motor down.
Do you know any reputable mechanics in western Washington?

 

[freak58trio]

Could possibly be piston slap.

 

[renotay]

X2 on the rod bearing, I'd tear the head off and check if it broke a ring or piston and is slapping on the head before you tear the whole motor out though

 

[powder_bound]

Thanks Guys, I will pull the head and look for damage first.

 

[rmkboxer]

the 800's do have a knocking noise in them from the pistons, I haven't heard one w/o it. we have a motor that makes the noise and it has less then 500 miles on it

 

[rmkboxer]

Thanks Winter Brew, guess I'll tear the motor down.
Do you know any reputable mechanics in western Washington?

where are you located?

 

[chater]

I had knocking in my motor on the same side, i lucked out and it was a broken exhaust valve on the pto side. Luckily it didn't hurt anything and all is good hope you have the same luck.

 

[powder_bound]

@RMKBoxer - This noise sounds like metal on metal, I don’t think its normal engine noise. I’m located in Fall City, WA

@Chater – I hope I get as lucky as you. Going to pull the head on Thursday night, sled is in Roslyn, WA right now. I will let you guys know what I find.

 

[cbc24]

lol i had the knock too turned out my cranks snapped 99 rmk 700

 

[rmkboxer]

@RMKBoxer - This noise sounds like metal on metal, I don’t think its normal engine noise. I’m located in Fall City, WA

@Chater – I hope I get as lucky as you. Going to pull the head on Thursday night, sled is in Roslyn, WA right now. I will let you guys know what I find.

pull your exhaust valves out and check them out. you would be amazed at what kind of noise the pistons make. if you are not familiar with them you would think something was wrong. I am in Bonney lake.

 

[powder_bound]

@RMKBoxer - I'll pull valves too, I bet there stock also. Prolly replace with the SS valves huh?

 

[rmjj]

let us know what you find. I have the same noise at the same RPM around 2500 only on a 03 700,mine does it cold or warmed up. dealer thought piston slap so pulled apart and ended up had a scored piston, I decided to replace them both as I had things apart. Sled had 6600 flawless miles so was time anyway. Put back together and noise is still there. To me it sounds like a exhaust valve clatering around but neither is broke. So today I pulled the valves and made a flat peice of metel to block them off. Started and noise still there. I to am dunbfounded as what next to do. Please keep the ideas comming. Thanks

 

[freak58trio]

Here's my thought's both the 700 and the 800 are noisy motors mine makes a knocking sound also and has 500 ish miles we just sold a 05 700 with low miles and it had a similar sounds come to find out it was the exhaust valves opening and closing. Now if you listen to my other sled which has a 99 non ves 700 it does not have any of the sounds that the ves 700 does so maybe something to do with the ves jug just thinking out loud.

 

[powder_bound]

Hey guys, I just pulled the head, exhaust valves and jugs. Everything looked ok to me except the PTO side valve diaphragm was all oily. I cleaned it off and noticed a tear in bottom side. I didn't pull the pins on the pistons but looked at rod bearings which looked and seemed ok. could the noise be from the PTO side exhaust valve? here are a few pics, are the black streaks normal on the pistons?

 

[rmkboxer]

the black is a teflon coating, I would put it back together and replace that bellow. If everything looks and feels good its the normal knock that is in all polaris 800 big blocks

 

[rmjj]

I thought maybe I maybe I had something in the clutch everything there looked good. I started the sled and the noise is gone, put clutch back on and noise is back. Could be a crank bearing ??? If so would'nt you hear it all the time not just at the 2500 RPM when coming back down to idle?