1966 18602C 18hp strange noise..help!

[berninga87]

Hello all, so I bought my first boat recently, an old 14ft sears flat bottom that came with the '66 18hp Evinrude. After some research I've come to believe this motor is probably a little overkill for the boat, and I was maybe a little naive when buying, but it's what I have to work with for now. Luckily I know two-stroke motors well enough and this one runs great and starts first pull most times, however my knowledge stops at the powerhead...The issue I'm having is in forward gear. When I shift into forward it starts to whine and gets louder and louder with more RPMs, to the point that I can hardly even hear the motor past half throttle. The prop is in OK shape..not new by any means and a little dinged but no big chunks missing. I replaced the lower unit gear oil(old oil was a little milky, but couldn't see any major amount of metal shavings.) I toyed around with it on the water for a while and the noise never changed, although sometimes I could hit the throttle and the boat would jump right up on a plane and go, others times it felt almost like the prop was cavitating and the motor would rev up but didn't pick up any speed. The noise still kept up, and got really annoying, I can't say for sure but it sounded like the noise was coming from somewhere in the upper part of the drivetrain, not something in the water, but it was hard to tell. I have tools and can do most repairs myself, I just dont know what could be causing it, help!

 

[boobie]

Re: 1966 18602C 18hp strange noise..help!

Sounds( no pun intended) like a problem in the lower unit. Like maybe a gear problem.

 

[berninga87]

Re: 1966 18602C 18hp strange noise..help!

I kind of thought so...but where should I start investigating? What do I do first?

 

[Chinewalker]

Re: 1966 18602C 18hp strange noise..help!

Gear whine. Not uncommon with those motors, particularly when the bronze bearings get worn. Drain the unit, noting the color and odor of the oil. Remove the lower skeg half of the gearcase housing. Check for wear on the gears and the bearing surfaces.

 

[berninga87]

Re: 1966 18602C 18hp strange noise..help!

Ok I'll do that soon as I can, hopefully get to it this week yet. Thanks.

 

[berninga87]

Re: 1966 18602C 18hp strange noise..help!

So I haven't gotten anything apart yet, but I was just looking it over and noticed if I wiggle the end of the prop hub there seems to be a lot of play in it, is some wiggle room acceptable or could this be a major issue/related to my noise issue?

 

[Cap'n Chaos]

Re: 1966 18602C 18hp strange noise..help!

What exactly is moving? These props do not have a hub in them... they are driven by a metal pin.

 

[berninga87]

Re: 1966 18602C 18hp strange noise..help!

Sorry, I don't know these things too terribly well yet. The best way I can describe it is there is a little rubber "cone" on the end of the prop with a cotter pin through it. If I grab that and move it, it has quite a bit of play from side to side and endplay forward and back, moves a little bit up and down. It sounds like something is moving on the inside with it when I wiggle it, but it seems to be moving as one unit, just not held in place very solidly...I hope that description is a little better. Thanks

 

[Cap'n Chaos]

Re: 1966 18602C 18hp strange noise..help!

That's exactly what it's called, a prop cone. If you remove that cotter pin the prop cone will come off and you'll see a nut behind that... behind that is a the drive pin "shear pin" which mates up with a notch in the back of the propeller.

The prop cone moving is no big deal, if the whole shaft is moving then you have a problem with the bearings that support the prop shaft.

Have a look at this diagram: (it's not for your exact motor but the gearcase is pretty much the same for these older motors.

http://epc.brp.com/AssemblyTree.asp...f8b-47c2-8df1-83b9cf4dd094&=&lang=E&siteid=1#

EDIT: My internet skills are lacking... I hope this link works.

 

[berninga87]

Re: 1966 18602C 18hp strange noise..help!

I think I definitely have problems with the prop shaft bearings....the whole thing moves, not just the cone. I have a parts diagram for my exact motor and I see the bearings you mentioned. Is my lower unit salvageable without major expense?

 

[berninga87]

Re: 1966 18602C 18hp strange noise..help!

Ok so I found another lower unit, supposed to be complete and ready to go, I sent the seller a message, but can anyone confirm if this will fit my motor or not? http://item.mobileweb.ebay.com/viewitem?sbk=1&nav=SEARCH&itemId=321183455811

 

[Chinewalker]

Re: 1966 18602C 18hp strange noise..help!

Back up a bit first...
There is SUPPOSED to be some rotational play in the propshaft as it rotates between the shift lugs on the gears and clutch dog, approx. 1/4 turn either direction when in gear.
There is SUPPOSED to be a small amount of in and out play in the propshaft, but no more than several hundredths of an inch.
If you are getting slop side to side, without turning the shaft or pushing it in or pulling it out, then yes, you have an issue. Take it apart - might be as simple as replacing a bearing, but you won't know until you take it down...

 

[berninga87]

Re: 1966 18602C 18hp strange noise..help!

Thanks for the help guys. I talked the guy who sold it all to me into buying the motor back on the basis that he promised a "ready to fish" boat/motor/trailer. It was too big for that little Sears boat anyway. I'm going to look at a 9.8 mercury today which will be a better fit. I'm taking a tool kit with me this time to check a few things and hopefully not make the same mistake again!