1998 Yamaha 25Hp 2 cylinder 2 stroke oil mix outboard making squeal noise just below

[99yam40]

Townsend, I'll check that tomorrow. With the lower unit off, I had planned on removing plugs and see what engine felt like. I will also put an indicator on the fly wheel and check end play. My guess is it should be very small. Probably less then .001 . Manual does not spec it. However like I said, with a precision two ear stethoscope, both upper and lower main crank bearings sounded fine at idle. Just a smooth whirr sound of them turning. Both bearings are ball and no seals, so they are lubed by the 100-1 oil premixed gas. I'm old school and usually mix it 75-1 just see a trace of blue smoke. See little carbon build up on piston tops and plugs.

99, I was watching some Youtube and they were saying replace water pump ever two years. At my age, if it pees the Urologist says be happy? HA... You're right about a lot of neglect. Few years ago, Hurricane Isabel came thru and surrounded my house with 3' of water just below living space and I am 9' above average high tide. It tore the boat free and floated it over my neighbors 3 foot chain link fence into his back yard. Took me two days to get it back over and onto my dock. It just may have gotten water in motor but it never went under.

Even at 75 to 1 the internals do not like sitting for long without running, rust will set in

[rodbolt17]

that's why I don't EVER recommend 100/1. I always recommend 50/1.
IF and only IF the engine is maintained AND run in accordance to the owners manual can you safely run 100/1.
OMC quit due to corrosion(rust) issues on the shiney parts during long term storage.
longterm is generally 30 days without running.
rusted/damaged ball bearings make a whirring or singing noise.
wont get any better and I have yet to have the machine faries fix one.

[grf00]

Thanks Rodbolt...Will use 50-1. What I have always used in the other 3 engines I have had. This motor has only had I gallon of oil thru it. When I fixed it up for the grandkids to take a ride, I purchased another gallon since the original is as old as the motor. When I get the seals and put lower unit back together , will post back if noise is still there and I split block

[grf00]

Well got it all back together. 50-1 oil. Ran it down the creek. Sounds fine. Think the key here was it sounded fine before and only after hot and then idling down it made the noise. Think it was the old hard rubber pump. Sure sounded like noise was at water line. I think if it was a bearing it would sound off all the time at idle when it was cold. Well now it has a new pump, shaft seals,shift rod seal and the wedge gasket between the intake and exhaust passage ways..along with some RTV on the corners. Does not look like a lot of motor for a 16' boat but in the turns, at WOT you fill a slow skate. You would not need to be going any faster. If you push it too hard and it skates out totally, it suddenly spins and heads in the direction you were turning away from. Just back from a run and flushing. Sound OK to you guys. Some shots of my recent conversion from a tiller control

https://www.youtube.com/watch?v=DTBAvOih934

[TownsendsFJR1300]

Sounded fine on You Tube. Couldn't get a much flatter bottom on the boat!

Nice little rig thou, like the ramp in your backyard!!

So the noise is NOT happening anymore under the same conditions as before?

Bet the impeller was pretty set and hard as heck too...

[grf00]

It was set but not that hard. Stiffer then the new one. That creek is the tip of Harris River that goes out into the Chesapeake Bay in Hampton VA. It can get rough not too far out into the river. You can drift fish in 1-2 foot rolls. Trouble is, if it sneaks up on you, you cannot drive into them. Has a habit of rolling over front and dumping 40 gals of water. Couple three and your in trouble since it's too heavy to plane and pull the plugs. We use to ride out and stay behind the point and beach it on the sand bar. Now, they don't want you too since so many migratory birds nest there. Probably end up selling it and getting a 18 or 20 open fisherman. Just could not sell it broke. Thanks for the help. My conversion to tiller is on RIPSAWSBOAT. I need to get the moderator to merge my two accounts and kill the new one ripsawsboat. Had been so long, I forgot I had this one.

[grf00]

Well all was well for a couple trips. Set 5 weeks and went out yesterday and motor would simple not take off. Starts and idles fine. When you throttle up on it, it simple acts like it's running out of gas. You can hear the ping from the advance coming in with no fuel. Can get a firm bulb on the tank hose, so think all is well there. When I came in, there appeared to be no fuel in top carb bowl when I broke drain plug. I rebuilt fuel pump getting motor back into running condition from setting. Is there a way to check fuel pump on the motor? Guess I will pull the carbs for the fourth time this year. Could it be the gas that has set for 7 weeks in the sealed 6 gallon tanks? (been in warm shed but out of the sun) Boats can be a pain...Eeeee

[TownsendsFJR1300]

Are you using any fuel stabilizer in the fuel???

Fuel, expecially the ethonol crap, will go bad in as quickly as a month. Even if you run the engine dry of fuel, there is a bittle bit in the fuel bowls that WILL varnish and clog up jets...

Either use a goodfuel stabilizer (most help with fuel separation as well) "Gas Shok" works very well. A little goes a long way;
http://www.coastus.com/index.phpmain...&products_id=3

Before I learned of this product, YEARS ago, on my carbed 140 Evinrude, the carbs clogged up. Cleaned them, ran fine. Week later, SAME THING. Clean them again. That's when I asked and learned about Gas Shok. Never had an issue after that.

[grf00]

No stabilizer and for once when last used, pulled the fuel line and let it run out of fuel and flushed motor. Probably would have been better to leave bowls full. Oh well, getting good at pulling them apart. Think I have the tools all memorized. Only 100 yards to the boat but I think I will just throw the box in the back of the truck and drive. If not, I usually make 5 trips. No special trick to make sure there is no trash in those two little one way poppet valves in the fuel pump other then taking it apart?

[TownsendsFJR1300]

Can't speak for the fuel pump but you main jet sounds like it varnished up closed.

Leaving un-treated fuel or just running it dry, won't cut it. That little bit left in the bowl (if run dry) can still clog your jets.

Good luck.

[grf00]

Top carb was clean. Bottom carb had light shellac crud sitting in the recess of the bowl were of course the main jet sits in. The jets were open but the crud was easily big enough to suck up and block jet and not pull thru. The 4 fuel pump screws were also not tight. When I rebuilt it, those three stack gaskets and diaphragm had set and let it get loose. However it was not dripping. One concern is one of the metal leaf check valves in the fuelpump will not hold fuel on one side in the small c-bore side. One will hold fuel 15 seconds. The other will not. I fiddled with it and flipped leaf over but appeared to make it worst. Probable may have to replace the black center section and the checks. However going out in a few on the high tide. If I do not write back tonight, someone come out and get me before I drift to Cuba. Taking the marine radio.

[grf00]

Made it back. Ran great. Nailed the pick up timing setting this time. However, seconds before the video ends, it was like the fuel shut off and engine bogged. Not sure if the run you see was the fuel bowls running empty and fuel pump problems or it sucked some more trash. If it's trash, must be tanks but they were spotless clean. Flushed and dried in the sun this spring. Going to check them tomorrow and the filter screen. Guess I will pull carbs again and see what is in bowls. If no trash and carbs are clean, guess I need the fuel pump body. Will try to lap seat with nothing to loose with extra fine lapping compound since that silly fuel pump is pretty expensive. Know if I was paying someone, this boat would be junk.

My run
https://www.youtube.com/watch?v=A3s82uq1WN8

[TownsendsFJR1300]

Made it back. Ran great. Nailed the pick up timing setting this time. However, seconds before the video ends, it was like the fuel shut off and engine bogged. Not sure if the run you see was the fuel bowls running empty and fuel pump problems or it sucked some more trash. If it's trash, must be tanks but they were spotless clean. Flushed and dried in the sun this spring. Going to check them tomorrow and the filter screen. Guess I will pull carbs again and see what is in bowls. If no trash and carbs are clean, guess I need the fuel pump body. Will try to lap seat with nothing to loose with extra fine lapping compound since that silly fuel pump is pretty expensive. Know if I was paying someone, this boat would be junk.

My run
https://www.youtube.com/watch?v=A3s82uq1WN8

I didn't see/hear ANY issues in that video.

I wouldn't pull the carbs at this point but maybe just the drain bolts in bowl and catch what comes out (I use a small tuna fish can super clean).

A pump or two on the primer valve should flush out any loose debris (if there's any in there).

I would definitly recommend a stabilizer, you've seen the varnish, even running dry. That or drain the bowls after every outing.

Also, depending on what type fuel hose your running, ethonol (if not made for it) can literally eat the inside of the fuel line. I had it happen (and it was mercury fuel line when they re-powered my boat) to the fuel line inbetween my transom filter and under cowl filter. (see below).

I saw black crap in the Yamaha filter, nothing in the transom filter. WTF? Gotta be that one short piece of hose or primer bulb. Sure enough, pulled that hose off, bits and pieces could be plucked from inside the line...Replaced both the line and the bulb (just in case there was crap in there). I just happened to notice the filter doing some maintainance under the cowl.. The Yamaha filter caught most if not all of it..

[grf00]

Runs like a champ now. Think my problem was two things. The lower carb had the trash but the tank had gotten water in it. I drained the carbs and checked the filter. That is when I saw about 1/16" of water in the jar. I ended up dumping 7 gallons of weed edger.. Runs like a champ now. The carbs on a two cylinder have two slots in the threads at 3 and 9 O Clock in the bowl so you do not need to screw them out since the bottom one is hard to get back in. However it needed to come out to dump trash. I pulled the inlet hose to make room and used a small piece of paper towel on my 6MM extension socket to secure screw to replace it and a ran in the bottom to catch it just in case. Obvious, the one way valves in the fuel pump do not need to seal very well.