View Full Version : Strange Noise Ideas needed.

88 PS190
08-16-2005, 09:19 AM
Our 1988 Prostar 190 has been making an odd noise that occurs while accelerating and if the throttle is backed off quickly while at skiing speeds. The noise only occurs for a limited portion of the acceleration, there is no noise when the throttle is engaged into gear but when it is pushed to pull a skier or just to accelerate quickly the noise comes in. I would describe it as a whining growl, but it goes away rather quickly, so far several mastercraft dealers have voiced opinions they are as follows.
1. Flex disk coupler between engine and tranny (possibly wouldn't stop making noise, plus we have no noticeable vibration)
2. Bad strut bushing/bearing surface transmitting vibration thru the hull (driveshaft is not sloppy at either end, including when the tranny/shaft coupler is unbolted (alignment is within .001))
3. Normal noise on acceleration the vibration is being transmitted, on deceleration the propellor cavitates as it slows down w/ the engine and causes the water to shake and make a noise. (shouldn't occur on acceleration as the prop would not be cavitating and if you back off the throttle during the noise the noise will stay till higher speeds.

I'm not sure which of these ideas to investigate as i've not seen conclusive evidence of any of them being correct.
We've just bought the boat so we do not have too much history on the noise. less than 700 engine hours, and the trans fluid (while old) is not off color, doesn't smell and is bright (no shavings or wear)

Thanks for any help, the boat is out of the water for the fall anyway, but anything that could help solve this before spring would be appreciated.

08-16-2005, 12:06 PM
Welcome to this site!!!
Hope someone can help you...

08-16-2005, 12:14 PM
With 700 hours on the boat, my first guess would be that the shaft bushings in the strut need replacing (recommended 300hrs I believe). Other than that, possible lack of lubrication (water) in the stuffing box. I'd make sure your stuffing box is dripping water like it's supposed to.

Workin' 4 Toys
08-16-2005, 12:17 PM
Assuming you have assured the prop is tight on the shaft. If you do not know how to check this, consult your owners/operations manual.

Second, I would lean towards your option number 1.

Have you tired it with the cover open, to see if there is a engine noice that accomodates the vibe?

88 PS190
08-16-2005, 02:42 PM
we ran it w/ the engine lid off and the rear deck removed, and the noise was hard to pin down, no particular area, althought w/ your head on the fiberglass of the hull you could hear it through the boat. I was thinking the flex disk would make alot of noise near the engine, and this seems more like a general howl. But its hard to hear it from the back of the boat. Personally when its assembled I hear it most from the driver's seat

In the few days we've owned the boat we've fallen in love w/ the thing, need to get this fixed and then we'll be in the money.

All our previous skiing happened behind our chris craft I/O runabout, which is basically skiing up a wake and down another one. Major improvement in wake size, boat tracking, and pull out of the water.

08-16-2005, 02:46 PM
In an attempt to isolate the noise, try using a 3-4 foot section of heater hose. Not quite as good as using a mechanics stethoscope but does the job....