Prop Shaft Noise

[kapt]

I have a 96' Evinrude 130 hp. When the prop shaft is turned by hand it makes a noise like gears are slightly meshing.If I pull outward on the prop it is smooths and no noise. I have pulled the carrier and replaced the seals twice in two months. The gears are perfect with no sign of touching each other or any visable wear at all. It runs without any vibration and shifts without any problems. The prop shaft has a slight bit of side play which causes the seals to fail quickly. Am I correct in assuming the front set of roller bearings are bad ?<br /><br />Please email replies to : kapt1951@yahoo.com<br /><br />Thanks.

 

[ob]

Re: Prop Shaft Noise

Hey kapt,Try adjusting the shift linkage.You'll have to remove the shift arm pin(not the shift rod)and while turning the prop,shift into forward,neutral ,and reverse,and then finally back to neutral by using just the shift arm.Make sure the the controls are in the neutral position and note the alignment of the shift arm pin hole.If it is not perfectly aligned,adjust the cable trunion until it is before re-installing the shift arm pin.<br /><br />The propshaft will have some lateral movement to it.You can only determine how much with the usae of a precision tool such as a dial indicator.This will let us know whether to recommend if you may have propshaft bearing issues.<br /><br />Many times the shift cable trunions are moved by boat owners in an attempt to adjust throttle linkages and are not returned to their previously set position ,causing a similar syptom of what you describe as a slight meshing sound when the prop is manually spun in neutral.Other times ,the shift cable just gets stretched out and needs to be re-adjusted.Hope this helps.

 

[kapt]

Re: Prop Shaft Noise

Tried the linkage adjust suggestion. Had no effect on the noise..

 

[ob]

Re: Prop Shaft Noise

Then what you're hearing may be bearing related.Are you hearing this noise with the propeller installed while spinning.Just trying to rule out a propeller skirt rub causing the noise.Noises are hard to describe and understand via internet to say the least.Keep postiing and someone may help you pinpoint you're issue.

 

[kapt]

Re: Prop Shaft Noise

It is not skirt noise. I pretty good with mercruiser outdrives and have rebuilt many. But tis is a mystery to me. As I said I have pulled the bearing carrier and all the gears and rear bearings are in excellent condition. With the bearing carrier out there is a lot ( 3/4 -1") of side play in the prop shaft. Also I can turn the shaft with the carrier out and still hear the noise. I know no gears are involved since none are turning with the carrier and rear gear out. it almost has to be in the front bearing. I assume the lower has to come off and the drivesahft and pinion removed to get at the front gear and bearing.

 

[kapt]

Re: Prop Shaft Noise

Note: 2<br /><br />I have never been inside one of these and I guess I need to know if it is a job for the experts or someone with a little knowledge can do it.

 

[ob]

Re: Prop Shaft Noise

Just listening to your comments leads me to believe that this task is well within your mechanical scope ,however I would secure the specifics of a service manual for the detailed points.Good luck,and tell us what you find.<br /><br />Off hand I can say that I don't know how much lateral movement would be present with the carrier removed.Look forward to your update.Bummer it wasn't something as simple as a linkage adjustment.

 

[kapt1951]

Re: Prop Shaft Noise

I have a 96' Evinrude 130 hp. When the prop shaft is turned by hand it makes a noise like gears are slightly meshing.If I pull outward on the prop it is smooths and no noise. I have pulled the carrier and replaced the seals twice in two months. The gears are perfect with no sign of touching each other or any visable wear at all. It runs without any vibration and shifts without any problems. The prop shaft has a slight bit of side play which causes the seals to fail quickly. Am I correct in assuming the front set of roller bearings are bad ?

I had the exact same motor with the exact same noise. I have a lathe so I pulled the lower unit apart and where the main carrier gear runs in the bearing on the front part of the shaft , I turned a stainless steel shim of .125 thickness and installed it on the shaft where it ran against the bearing race and re-assembled the unit. The noise is from the gears slightly touching each other when turned by hand. After the repair , the noise is gone and the motor has been running perfectly for 6 years. You will need to measure the end play to get the correct shime size. Your may not require .125 ot it may need more.