'91 Yamaha 200 noise - help needed

[samsims]

I have a noise that only occurs under load. At 2.5k rpm it you can really here it. At idle there is no noise. Sounds like a bearing, its meadium in pitch, not high pitched at all. It varies with engine rpm. I am guessing a crank or rod bearing. The engine has close to 1000 hours on it. Just did a compression check: left bank,112-115-110, right bank,106-111-110. The engine runs fine, power is fine for its age. I plan to pull the manifold on sunday to check things out. What should I be looking for? I don't that much experience with outboards, at least with internal problems. Have lots or 4 cycle car engine experience. If it is a bearing I plan to just get a rebuilt power head, the engine is about at that point I believe. Any advice on where to get a GOOD rebuilt power head from? Any advise on what the problem might be and what I should do? Thanks.<br /><br /><br />Stacy

 

[rodbolt]

Re: '91 Yamaha 200 noise - help needed

check the gearcase magnet. usually with a 2stroke and needle bearings your fist inkling that a bearing is loose is when it appears outside the block. the bottom main is a roller and will fail as well. test by using a dail indicator and lifting up on the flywheel. should have less than about .010" of vertical motion.<br />good luck and keep posting

 

[samsims]

Re: '91 Yamaha 200 noise - help needed

Thanks for the reply! I just tested the fly wheel, got .004" of play. Also drained the gearcase, not much on the magnet, just the usual very fine gray stuff and not much of it. Nothing big anyway.<br /><br />Stacy

 

[vinney]

Re: '91 Yamaha 200 noise - help needed

The bottom main bearing on the crankshaft is bad. Its a Koyo bearing with a plastic insert.The insert is put in there to hold the balls of bearing in there proper spacing. The plastic fails and all the balls gang together. You can replace the bearing with a steel insert that won't fail. If the engine has 800 plus hours. Its the most common reason for noise. If the engine runs well and is loud(sounds like a can of marbles)and happeneds under load its the bottom main bearing.

 

[rodbolt]

Re: '91 Yamaha 200 noise - help needed

hello<br /> is it a double click? if your a tech and you think its a bearing then look at wristpin bearings. some times they fail and will clatter a bit before coming unwound.<br /> good luck and keep posting

 

[samsims]

Re: '91 Yamaha 200 noise - help needed

vinney-<br />Ah yes, "can of marbles" is the term I was looking for, thats definitly what it sounds like.<br /><br />If that is the problem, my manual says the crank has to come out. Is it worth pulling it apart and doing just the bearing (and whatever else I run into). I am in a squeeze for time and need to decide to pull it apart or just go with another power head.<br /><br />Can I run it for a half hour or so on that bad bearing or should have it towed to the launch?

 

[vinney]

Re: '91 Yamaha 200 noise - help needed

You can pull the power head and pull the bottom bearing cover and sneak the bearing out and replace it. We as a repair facility would never recommend this But it can be done. The bearing is about 30 bucks. We had a 200 Yamaha that ran three years with the bottom bearing sounding like a can of marbles. We made a bet with the customer. That if We were wrong We would fix the engine for free. He wrote the check. His engine is quiet now.

 

[rodbolt]

Re: '91 Yamaha 200 noise - help needed

hello<br /> my bad. I dont know why I said the bottom was a roller. it is a ball and cage. and the cages will fail on occasion. if you suspect its a bearing you need to find and repair it before it takes itself apart.<br /> Vinney gave ya good info. so now its up to you <br /> good luck and keep posting

 

[samsims]

Re: '91 Yamaha 200 noise - help needed

You guys were right on it! That lower main roller bearing is toast. Took awhile to get to, broke two power head bolts. Now a new question. <br /><br />What is the fix for that corroded steering arm, is there a stainless version available? I don't even want to see th price an that!

 

[vinney]

Re: '91 Yamaha 200 noise - help needed

Steering arm. You run the engine till it breaks or close to that. With an engine that old its not worth fixing the steering arm. Unless the rest of the engine is perfect. Sounds like it time to repair the bearing and run it till the rods hang out the side of the block. With a 1000 hours on the block it will last a couple hundred more hours and then Its time to get a payment(New Yamaha 200 HPDI).