99 Air transmission noise

[mevirga]

Hi-
I have a 99 Air with a GT-40 that is making what sounds like a transmission noise only when in neutral. I would describe it as a "rowel....rowel....rowel" , at medium pitch. The noise completely disappears when the boat is put in forward or reverse gear. It drives and performes normally. Could this be a throw-out bearing, or other bearing, as in a car? Any advice would be greatly appreciated.

Thanks.
Mike

[mevirga]

revised description of noise

I know this it starting to sound weird, but I dont know how else to describe the sound short of uploading an audio file. The sound I described is not quite correct. Its more like a cricket but not high pitch.

Any ideas?

[WakeSlayer]

Have you checked or changed the fluid? Any slippage?

[mevirga]

fluid

ya know...thats a good point. I had a 96 Sport that I just sold. I changed the tranny fluid every year and never heard any noises other than the normal Nautique whine and reverse backlash rattles. This boat has 1/2 hours & while test driving it, the prev. owner said the engine oil and tranny fluid had just been changed. I checked the engine oil and it was new and full, but did not physically check the tranny fluid. I heard the noise at the time I test drove it, but thought it was subtle at the time and did not pay much attention to it. Now that I have bought the boat and have a lot more time to nit-pik, I've keyed in on this noise and it bugs me more. I also think it didn't bother me that much at the time because the boat drive great. No slippage, plenty of power, & more responsive than my Sport. Good call though Slayer. I'll start with the basics and do a tranny fluid change myself and see if it changes. One question...do you know if there a throw bearing down there and has this noice been described before?

Thanks.

[jimmyj]

this might be an obvious question, but why would the transmission be making noises while the boat is in neutral? i might be reading something wrong....

[mevirga]

No..you're reading correctly. Not sure if it even is the transmission. Not sure what it is. I just remember I had a truck that did the exact same thing and it ended up being the throw-out bearing associated with the clutch. Do these boats have clutches?

Thnaks.

[WakeSlayer]

There is no throw out bearing. There is a damper plate bolted to the flywheel. That is defnintely a possibility. However if there were a problem there, I would think you would hear that under power, not so much in neutral. I could be wrong.

Call Eric here: http://www.fantasticfinishmarine.com/

[mevirga]

Thanks Slayer. Im going to do a tranny fluid change tomorrow and if that doesn't help, I will give Erik at FFM a call. I'll keep following up on the forum so others can maybe garner some info if they're having the same issue.

[mevirga]

That's one hard dude to get ahold of!...but still spoke with Erik today. Super knowledgeable, friendly, & willing to take the time. He basicallly told me to get used to the noise and as long as that PCM TRANS works, use it because if they go, they go quick. Im going to change the fluid and run it til it breaks. Will post if anything changes.
Slayer- thanks again for the ref.

[mevirga]

More info

Changed the tranny fluid and took the boat out again last weekend. It ran and performed great again, but still the quick "rar,rar,rar,rar,rar" noise in neutral. Bugging me! I just cant turn the stereo up to mask it. Need to fix the problem. Talked to 2 CC dealer service guys and both said this is a common concern/issue with the PCM PP 1:23:1. Both explained it as clutch plates that have been warped due to high temp in the tranny at some point in it's life. They suggested I check to see if the prop & shaft turn while the boat is running in neutral on the trailer. If so, then the clutch should be replaced. But also said I might as well RR the tranny while in there. Anyone been through this? Surprised not to find similar info on PN if it's a "common" problem.

Thanks.
Mike

[intrlaz]

I have a similar noise in my 02 SAN. It is very annoying. Dealer told me the same thing he told you about PCM transmission dying a quick death. Keep us updated on your progress

[mevirga]

more info

Thanks intrlaz. Will do.

[mevirga]

dampener or clutch plates

Okay, I did some more research on this. Can someone more mechanically inclined take a read below and let me know if I'm understanding this correctly? Again, thanks for the help PN community.

It's most likely 1 of 2 issues causing the rapid paced "rer,rer,rer,rer,rer,rer" noise in neutral- clutch or dampener plate. These 2 parts transfer power between the engine & the transmission. The major part flow from front to back is as follows- engine/crankshaft, flywheel, dampener plate, clutch, transmission, drive shaft/prop.

Dampener plate- (part cost +-$100)
This plate bolts to the flywheel and has springs in a circular pattern. It engages the clutch as the boat is shifted into gear. Sometimes this plate becomes loose and/or the springs become unseated and can cause a noise like I'm experiencing. It only does this in neutral because the it's not engaged to the clutch/tranny and is only spinning with the flywheel, knicking the clutch plate & causing the noise. When the boat is shifted into gear, the noise goes away because the plate is firmly mated with the clutch/tranny. If the spring(s) become completely unseated or the dampener plate loosens entirely from the flywheel, all heck breaks loose and you're stranded on the lake.

Clutch (part cost +- $200)
There are #? circular clutch plates between the dampener plate and the transmission that are the final transfer of power between the engine and the transmission. If the tranny ever heated up for whatever reason (usually low or dirty fluid) these plates can warp and cause the same issue. Instead it would be a warped clutch plate being knicked by the dampener plate in neutral. The way to test this is to start the boat on the trailer and visually check if the drive shaft/prop is turning. If it is turning, the clutch plates are most likely warped and being knicked by the dampener plate while it's spinning in neutral. If the drive shaft/prop are NOT turning, the noise is most likely coming from a faulty dampener plate.

The noise is most likely originating from this point, whether its warped clutch plate(s) or a faulty dampener plate. The best way to determine which part is causing the problem without tearing into the tranny is to inspect the drive shaft/prop while the boat is running on the trailer in neutral, as described above.

[mevirga]

fixed

Damper plate replacement- $450 at Larsen Marine in Stockton, CA. They did a great job and only had the boat for 3 days in the middle of summer. No more noise.

PN- thanks for all the help

[lapextreme]

i have a 93 sport and have the same problem, change the trans fluid with amsoil atf and went out this weekend, pulling skiers for about three hour when the noise started, lasted about 30 min and then stopped, check trans look ok still wondering why it was making the noise and hopping it will not come back ,boat only has 380 hr on it