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Test run results since pump rebuild on 96 challenger
- Thread starter lilngineer
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lilngineer
Well-Known Member
Not being comfortable with the noise and vibration I scheduled a lake test with my dealer.
The tech took it out and it turns out the problem is not in the pump at all! He discovered that one of the RAVE valves is hitting the piston apparently. Not sure how this could have happened or how long it has been happening.. The engine was rebuild professionally about 30 hours ago, but by the previous owner. They are supposed to be a reputable shop, but who knows.
Anyhow they plan to cut back the valve a bit and replace therave gaskets/o-rings to fix. In the process, they will check compression and inspect the cylinder/piston with a fiber optic scope. Total cost with the lake test is $160. So I gave them the go ahead.
Has anyone ever heard of anything like this? I hope the internals are ok. I did check compression recently and both cylinders were right at 150psi.
The tech took it out and it turns out the problem is not in the pump at all! He discovered that one of the RAVE valves is hitting the piston apparently. Not sure how this could have happened or how long it has been happening.. The engine was rebuild professionally about 30 hours ago, but by the previous owner. They are supposed to be a reputable shop, but who knows.
Anyhow they plan to cut back the valve a bit and replace therave gaskets/o-rings to fix. In the process, they will check compression and inspect the cylinder/piston with a fiber optic scope. Total cost with the lake test is $160. So I gave them the go ahead.
Has anyone ever heard of anything like this? I hope the internals are ok. I did check compression recently and both cylinders were right at 150psi.
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Pretty good price....
I think you got a pretty fair shake from the mechanic.
You said the engine was just rebuilt ....but, you say by the previous owner. The one thing you'll see in rebuilding the Rotax engines is that often, they will bore over .010 and not take into account, the RAVE has to be shaved .005 to make up the difference in the piston size.
If you have good compression and the knocking was slight and caught fairly quickly, then you might be o.k. with the RAVE repair.
I did not read the 50 some odd posts to this thread, so I base this on the last post lilngineer made............:cheers:
I think you got a pretty fair shake from the mechanic.
You said the engine was just rebuilt ....but, you say by the previous owner. The one thing you'll see in rebuilding the Rotax engines is that often, they will bore over .010 and not take into account, the RAVE has to be shaved .005 to make up the difference in the piston size.
If you have good compression and the knocking was slight and caught fairly quickly, then you might be o.k. with the RAVE repair.
I did not read the 50 some odd posts to this thread, so I base this on the last post lilngineer made............:cheers:
lilngineer
Well-Known Member
Louis,
Thanks for the opinion. I am on pins and needles until the morning when the tech gets into it and knows how extensive the damage was.
Normally, I would have performed the work myself, but the price seemed reasonable so I figured I'd let someone with a heck of a lot more seadoo experience handle it.
Question: Since I have owned it (February this year), I have had it out probably a half dozen times for short test runs in an attempt to diagnose the problem. It always ran great above idle and I could not hear the noise or vibration. It was always only at idle (in the water). Is this because the valve was opening away from the piston at higher RPMs and thus not making contact?
Thanks,
Jason
Thanks for the opinion. I am on pins and needles until the morning when the tech gets into it and knows how extensive the damage was.
Normally, I would have performed the work myself, but the price seemed reasonable so I figured I'd let someone with a heck of a lot more seadoo experience handle it.
Question: Since I have owned it (February this year), I have had it out probably a half dozen times for short test runs in an attempt to diagnose the problem. It always ran great above idle and I could not hear the noise or vibration. It was always only at idle (in the water). Is this because the valve was opening away from the piston at higher RPMs and thus not making contact?
Thanks,
Jason
Rave....
No....you should actually hear the tapping as soon as you start up. The RAVE is closest to the piston at idle. When you increase the throttle, increasing the exhaust gas pressure, the bellows begins to build pressure in it till it overcomes the spring tension, then begins to lift the RAVE guillotine (slide) valve, making the exhaust port bigger. So, at WOT, the RAVE should actually be further away from it.
Also, if the tapping was the RAVE being hit by the piston, I'd want to see that slide valve. If the boat is with the mechanic now and you ask, if he's honest, he'll show you yours. But, if there was no damage to your RAVE and he's not honest, he'll show you one from a damaged boat.
I'm very much a pessimist when it comes to marine mechanics. I find it very hard to trust them. It's a shame because I know there are good ones out there who have their reputation tarnished by all the others that want to screw customers around.........but in your case, the ride and diagnosis sounds fair.
No....you should actually hear the tapping as soon as you start up. The RAVE is closest to the piston at idle. When you increase the throttle, increasing the exhaust gas pressure, the bellows begins to build pressure in it till it overcomes the spring tension, then begins to lift the RAVE guillotine (slide) valve, making the exhaust port bigger. So, at WOT, the RAVE should actually be further away from it.
Also, if the tapping was the RAVE being hit by the piston, I'd want to see that slide valve. If the boat is with the mechanic now and you ask, if he's honest, he'll show you yours. But, if there was no damage to your RAVE and he's not honest, he'll show you one from a damaged boat.
I'm very much a pessimist when it comes to marine mechanics. I find it very hard to trust them. It's a shame because I know there are good ones out there who have their reputation tarnished by all the others that want to screw customers around.........but in your case, the ride and diagnosis sounds fair.
lilngineer
Well-Known Member
Louis,
Take a look at post 39 of this thread. There is a sound clip of the actual noise with the boat in the water.
The noise was apparent at idle once started and up to maybe 2500-3000 RPMs. It was however, kind of erratic (i.e not continuous or cyclic). I could never identify it (and neither did the tech) when not in the water, though, over the exhaust and thrust bearing noise.
Once I had the engine above that RPM range, the sound/vibration disappeared.
I was already having thoughts of inspecting the valve prior to reassembly.
I do appreciate your help. Thanks, Jason.
Take a look at post 39 of this thread. There is a sound clip of the actual noise with the boat in the water.
The noise was apparent at idle once started and up to maybe 2500-3000 RPMs. It was however, kind of erratic (i.e not continuous or cyclic). I could never identify it (and neither did the tech) when not in the water, though, over the exhaust and thrust bearing noise.
Once I had the engine above that RPM range, the sound/vibration disappeared.
I was already having thoughts of inspecting the valve prior to reassembly.
I do appreciate your help. Thanks, Jason.
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ski-d00
Well-Known Member
I've seen pistons hit the rave valves and it usually does major damage, have seen a couple that were just touching that did basically no damage but I've never been able to actually hear one hitting. I'm not convinced that's it especially since you only heard it at idle, I would expect it to get louder, not go away.
If it was professionally rebuilt, the piston shouldn't be hitting the rave. I would call that an amateur rebuild since that's basic knowledge.
I still think it's the seadoo pump knock, you can pull the pump and driveshaft as long as you still hear it on the trailer but most of them you can't because they rev at much higher rpms out of water.
If it was professionally rebuilt, the piston shouldn't be hitting the rave. I would call that an amateur rebuild since that's basic knowledge.
I still think it's the seadoo pump knock, you can pull the pump and driveshaft as long as you still hear it on the trailer but most of them you can't because they rev at much higher rpms out of water.
Agree...
I pretty much agree here. It is unusual for you to be able to hear the clicking of the RAVE while in the water and the engine running, unless he used the engine stethoscope. I've seen them as he states, just a little dinged up, maybe a chip or beaten up pretty bad and piston damage.
Pump knock?......I'm unfamilar with that terminology. The only thing I can come close to thinking your referring to is when a bearing is out of tolerance and it wobbles the shaft, usually striking the wearing ring. What's your take on the definition?......
I pretty much agree here. It is unusual for you to be able to hear the clicking of the RAVE while in the water and the engine running, unless he used the engine stethoscope. I've seen them as he states, just a little dinged up, maybe a chip or beaten up pretty bad and piston damage.
Pump knock?......I'm unfamilar with that terminology. The only thing I can come close to thinking your referring to is when a bearing is out of tolerance and it wobbles the shaft, usually striking the wearing ring. What's your take on the definition?......
lilngineer
Well-Known Member
I assume the "pump knock" ski-d00 is referring to is the known thrust bearing noise heard when out of the water.
I have changed nearly everything in the pump short of the impeller shaft. My initial description of the noise was that the impeller sounded like it was hitting on the wear ring. (Post 39 has a clip)
I still do somewhat doubt that the RAVE valve is really causing the problem. I guess I will know more in the morning.
I have changed nearly everything in the pump short of the impeller shaft. My initial description of the noise was that the impeller sounded like it was hitting on the wear ring. (Post 39 has a clip)
I still do somewhat doubt that the RAVE valve is really causing the problem. I guess I will know more in the morning.
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ski-d00
Well-Known Member
seadoo pump knock is very common on older crafts, up to 99 or so til they went to the better spring design in the pump cone, even then some still have it. it is kind of a rattling knocking noise that is heard only at idle normally just in the water, once you get above 1600 rpm or so it completely goes away, some are really bad, some don't have it at all.
lilngineer
Well-Known Member
Is it actually common to hear it while in the water?
BTW, I retrofitted my 96 pump with the 97 cone w/pusher during my troubleshooting phase and it made zero improvement.
ski-d00
Well-Known Member
Yeah, I've done a few with the new spring/cone design and it didn't help. Normally it does help and sometimes eliminates it completely. Has always been one of the oddest things, have also had some success using the newer larger bumpers on the ends of the driveshaft. The noise is from the impeller shaft moving back and forth and can sound like a rod is knocking on bad ones, if it clears up by 2000 rpms,most likely it's pump knock and yes you can definitely hear them in the water normally worse. Pump knock will always have an exact rpm where it goes away.
I couldn't get your mp3 to work, my computer thinks it's a corrupt zip file no matter what I do.
I couldn't get your mp3 to work, my computer thinks it's a corrupt zip file no matter what I do.
lilngineer
Well-Known Member
how to get the clip
Assuming you are on vista, here is how to download it. Go to the documents folder (or any folder in windows explorer). Click "organize", then "folder and search options". Under the view tab, uncheck "hide extensions for known file types" then click apply.
Now go back to post 39 and right click on the file and "save target as". When the prompt comes up, remove the ".zip" at the end and you will have the file.
I know its a PITA, but the forum doesnt allow mp3 uploads.
Also, I am interested in the large shaft bumper design. Do you know a P/N or what years/models use it? I would like to retrofit mine once I take it out for a test run and discover that the RAVE valve repair didnt cure my problem!
Assuming you are on vista, here is how to download it. Go to the documents folder (or any folder in windows explorer). Click "organize", then "folder and search options". Under the view tab, uncheck "hide extensions for known file types" then click apply.
Now go back to post 39 and right click on the file and "save target as". When the prompt comes up, remove the ".zip" at the end and you will have the file.
I know its a PITA, but the forum doesnt allow mp3 uploads.
Also, I am interested in the large shaft bumper design. Do you know a P/N or what years/models use it? I would like to retrofit mine once I take it out for a test run and discover that the RAVE valve repair didnt cure my problem!
Rave????
wow . Could not imagine that noise being the rave hitting the piston. I think you can go two sizes over on the cyl (Well at least one) and still not have to notch the rave's. Even then I think it would snag a ring, with the noise yours is making. And if you have 150/150 compression?......
I used pusher cone;
http://www.parkeryamaha.com/seadoopumpconekit295500542.aspx
and new pumpers;
http://www.parkeryamaha.com/seadoodriveshaftbumperplug272000019.aspx
I also use a new neopreme seal every time I r&r pump
http://www.parkeryamaha.com/seadooneoprenepumpseal293200024.aspx
With the above seal All I need is a little rvt around the water inlet tube on the pump that goes through the transom, Easy clean up for the next time and still air tight
I use to have the knock and was told by a mechanic it was a rod knock. After the new cone and bumpers I have zero knock.
I Listen to the clip lilngineer the day you posted I think. My sound was not like yours. Yours sounds like it is in the hull. Mine was a crisper metal on metal tap/knock noise. If you stuck your head int the engine compartment it got louder.
I will be interesting to hear what the mechanic says. Please keep us posted on the outcome.
wow . Could not imagine that noise being the rave hitting the piston. I think you can go two sizes over on the cyl (Well at least one) and still not have to notch the rave's. Even then I think it would snag a ring, with the noise yours is making. And if you have 150/150 compression?......
I used pusher cone;
http://www.parkeryamaha.com/seadoopumpconekit295500542.aspx
and new pumpers;
http://www.parkeryamaha.com/seadoodriveshaftbumperplug272000019.aspx
I also use a new neopreme seal every time I r&r pump
http://www.parkeryamaha.com/seadooneoprenepumpseal293200024.aspx
With the above seal All I need is a little rvt around the water inlet tube on the pump that goes through the transom, Easy clean up for the next time and still air tight
I use to have the knock and was told by a mechanic it was a rod knock. After the new cone and bumpers I have zero knock.
I Listen to the clip lilngineer the day you posted I think. My sound was not like yours. Yours sounds like it is in the hull. Mine was a crisper metal on metal tap/knock noise. If you stuck your head int the engine compartment it got louder.
I will be interesting to hear what the mechanic says
. Please keep us posted on the outcome.
ski-d00
Well-Known Member
OK, I just listened to your mp3 and it definitely sounds like pump knock to me. I've battled with a few of them trying lots of different things, here is a list, as I remember, in order of what has worked better than others from my experience...
1. new cone spring system
2. new larger driveshaft bumpers
3. shifting the motor slightly towards the back
4. slightly thicker thrust washer, as I remeber about .020"(it was the mid 90s since I tried that)
5. new impeller
Like I said before, there were a couple that I just couldn't get to go away and gave up due to the time spent on it. I haven't gone past changing the cone spring system in many years and just tell people it is an unfortunate, but normal, sound and turning up the idle slightly will make it go away, or you just live with it as nothing is harmed by it.
1. new cone spring system
2. new larger driveshaft bumpers
3. shifting the motor slightly towards the back
4. slightly thicker thrust washer, as I remeber about .020"(it was the mid 90s since I tried that)
5. new impeller
Like I said before, there were a couple that I just couldn't get to go away and gave up due to the time spent on it. I haven't gone past changing the cone spring system in many years and just tell people it is an unfortunate, but normal, sound and turning up the idle slightly will make it go away, or you just live with it as nothing is harmed by it.
lilngineer
Well-Known Member
Ski-d00 & others,
Thanks for all the help. I am still waiting on the mechanics call to discuss prior to work.
I appreciate the list.
I was unaware of any larger bumpers. Do you know of a part number?
I still wonder if the solas might be a little sloppy fitting on the driveshaft splines. I have a new skat impeller I was thinking of trying, but I am really tired of r&r on the pump assembly.
With all this said, what are the chances the RAVE valve still needs repair? I don't want it shaved for no reason. It seems this might rob performance if that was the case.
Thanks for all the help. I am still waiting on the mechanics call to discuss prior to work.
I appreciate the list.
I was unaware of any larger bumpers. Do you know of a part number?
I still wonder if the solas might be a little sloppy fitting on the driveshaft splines. I have a new skat impeller I was thinking of trying, but I am really tired of r&r on the pump assembly.
With all this said, what are the chances the RAVE valve still needs repair? I don't want it shaved for no reason. It seems this might rob performance if that was the case.
lilngineer
Well-Known Member
Well I got the boat back. They ended up cutting the RAVEs back. Good news is that there was no internal damage since they were barely hitting.
After speaking with the mechanic, he told me he discovered it when opening up one of the RAVE valves while looking for the vibration. He didn't hear it hitting, but felt it by hand. Upon inspection, he thinks the rebuilder might have been slightly off center when boring to the point that the valve was just touching. Who knows? Anyhow he put them into tolerance, cleaned them up and replaced the gaskets and o-rings.
I also clarified with him that what I was describing in this thread was normal seadoo pump knock. So the RAVE valves were not really the "cause" of the viration/grinding I was describing as the service manager informed me it was.
Two seperate issues so to speak. So I guess it's a matter of perspective.
Either way, I guess better safe than sorry with the RAVEs. But I'm sure after taking it back out to the lake, it will be back to the drawing board on quieting the pump knock.
After speaking with the mechanic, he told me he discovered it when opening up one of the RAVE valves while looking for the vibration. He didn't hear it hitting, but felt it by hand. Upon inspection, he thinks the rebuilder might have been slightly off center when boring to the point that the valve was just touching. Who knows? Anyhow he put them into tolerance, cleaned them up and replaced the gaskets and o-rings.
I also clarified with him that what I was describing in this thread was normal seadoo pump knock. So the RAVE valves were not really the "cause" of the viration/grinding I was describing as the service manager informed me it was.
Two seperate issues so to speak. So I guess it's a matter of perspective.
Either way, I guess better safe than sorry with the RAVEs. But I'm sure after taking it back out to the lake, it will be back to the drawing board on quieting the pump knock.
You are right. You can go to first oversize (.25 mm) without shaving the valves. If you go to second oversize (.5 mm) you must shave the valves by at least .005".
Chester
lilngineer
Well-Known Member
I got a chance to take the boat out again since the RAVE valve repair. I cannot believe it, but the noise/vibration is gone.
I don't believe that the RAVEs were actually producing the noise, but maybe vibrating the hell out of the pump and causing excessive "pump knock".
I am so happy the problem is finally solved. The engine idles smooth as can be!
Thanks again to everyone who tried to help.
I don't believe that the RAVEs were actually producing the noise, but maybe vibrating the hell out of the pump and causing excessive "pump knock".
I am so happy the problem is finally solved. The engine idles smooth as can be!
Thanks again to everyone who tried to help.
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