Engine tapping or knocking noise at idle - looking for possible sources

[gsteffens]

I am considering the purchase of a 2000 GTX RFI Millennium Edition 782cc that is making a pronounced tapping or knocking noise at idle which you can hear in the video. I rev the engine and the sound goes away. Engine does idle but a bit rough. Recent work: new fuel pump, filter, fuel injectors, cleaned air system, new plugs, new coil, battery.

I've searched the forum and checked some of the suggestions - compression tests are at 151/156 psi and tried to locate the sound with a screwdriver but can seem to find it. Could the rotary valve make this sound? Any thoughts or suggestions on what this might be?

[video]https://plus.google.com/u/0/photos/106697122893831777123/albums/6057910021518863889/6057910027247425538[/video]

 

[Unclebob]

does the sound go away when you pull either of the plug wires?

 

[j.moret66]

does the sound go away when you pull either of the plug wires?

really can,you do that, are you serious?

 

[griz400]

hard to say by listening, i see you have 14 yr old oil lines on it .... i would pull the raves and look, maybe one is chipped off or something ... btw, that motor only idles on 1 cylinder, when you rev it it runs on both ... does it make that noise in the water ??? if not, its in the driveline -- or the seadoo rattle ...

 

[gsteffens]

does the sound go away when you pull either of the plug wires?

I will have to go back to the seller and try this. Does it matter which plug wire? If the noise goes away what would that indicate?

 

[gsteffens]

hard to say by listening, i see you have 14 yr old oil lines on it .... i would pull the raves and look, maybe one is chipped off or something ... btw, that motor only idles on 1 cylinder, when you rev it it runs on both ... does it make that noise in the water ??? if not, its in the driveline -- or the seadoo rattle ...

Just ran it on the hose this time so our next step is to water test it. When I first saw the ski the seller couldn't get it to idle/run right away. We came back a few days later to compression test it and he put new spark plugs in and it fired right up. Will try to pull the raves and look for something amiss. The seller says it's made that noise for years but it sounds metallic so that is what concerns me. If I put it in the water and the noise goes away should I be concerned any further?

 

[suke]

if it's the seadoo pump knock my sounds like my engine is gonna fall apart, but it's the normal pump knock. Obviously goes away once I get some load on it.

 

[LouDoo]

It sounds to me that it's the Seadoo rattle, which is completely normal. There's about 1/8" play in the pump, when the pump is under load the noise should go away.

Lou

 

[suke]

It sounds to me that it's the Seadoo rattle, which is completely normal. There's about 1/8" play in the pump, when the pump is under load the noise should go away.

Lou

Yup if it was an engine noise it wouldn't go away with RPMs. It'd get worse.

 

[gsteffens]

Thanks everyone for the input!

 

[j.moret66]

If the mystery ever gets solved, let us know.

 

[MichaelGSX]

It sounds to me that it's the Seadoo rattle, which is completely normal. There's about 1/8" play in the pump, when the pump is under load the noise should go away.

Lou

Would a anti rattle cone help with that?

 

[j.moret66]

I was there with gsteffens and filmed the video, it didn't sound like it was coming from that far back in the hull, it seemed to be right in the engine area.

 

[LouDoo]

I was there with gsteffens and filmed the video, it didn't sound like it was coming from that far back in the hull, it seemed to be right in the engine area.

The only way I know to get a definitive answer is to pull the pump, pull the drive shaft, and see if you still have the noise.

Lou

 

[j.moret66]

Lou, The guy won't let us take it for a water test so I'm sure he won't go for pulling it apart.

 

[LouDoo]

A water test would tell you if it's pump noise or not. If it were me I think I would pass.

Lou

 

[j.moret66]

Thanks Lou, sound reasoning, it's tough to pass up when u find a ski in as good as condition as this one. And I still want to solve this sound just so I can sleep at night

 

[jammin777]

the price should drop way down without a water test. a ski can run great all day long on the trailer water testing makes a world of difference. it's like buying a car without a test drive but worse. offer half the asking price or walk away.

 

[suke]

I was there with gsteffens and filmed the video, it didn't sound like it was coming from that far back in the hull, it seemed to be right in the engine area.

yup, still sounds like pump knock. An engine knock would only get worse with RPM. I've never seen an engine noise ever get quieter with RPMs.

 

[suke]

the price should drop way down without a water test. a ski can run great all day long on the trailer water testing makes a world of difference. it's like buying a car without a test drive but worse. offer half the asking price or walk away.

agreed! No water test, take a couple hundred off.....

 

[WhiskeyD]

I know I'm a few days late on this but this does not sound like pump rattle to me. Sounds more like a dirty RAVE clipping or something else internal. I'd personally leave this ski unless it was an absolute steal.

 

[j.moret66]

That's kind of what I was thinking it might be since the engine runs so well and has such good compression. He came down to $2000 and the ski is in really really good condition for a for the year.

 

[AdamXP800]

Did y'all watch this video? It sounds like chit! Sounds like something internal

 

[Sportster-2001-951C-Stock]

Grab a 2" piece of PVC pipe and use that as a stethoscope to locate the source of noise? Maybe something's caught in the RV meat-slicer?

Is this ski priced right for a reman motor install if that's what it comes to?

 

[jammin777]

Did y'all watch this video? It sounds like chit! Sounds like something internal

agreed, dosn't sound like the normal pump rattle to me.