Yam 90 2-st 99 impeller change

[BugEyes]

Hi,<br /><br />I got my boat and motor now and want to change the impeller to be sure it's fresh.<br />I ordered the Seloc manual but it's backordered for weeks. I'm not familiar with how to separate the shift linkage on this engine.<br /><br />Can anybody describe how to get the lower unit off? <br /><br />Is there anything else than the shift linkage and drive shaft that needs to be unlinked?<br /><br />Thank's

 

[BugEyes]

Re: Yam 90 2-st 99 impeller change

Oops!<br /><br />I should have seached better before posting. Found another tread with a link to a good description of the job for a 115 hp.<br />Will this description be valid for my 90 hp as well?<br /><br /> http://www.thehulltruth.com/forums/thread-view.asp?tid=79469&posts=12&mid=885897

 

[rodbolt]

Re: Yam 90 2-st 99 impeller change

pretty much, I dont think the 90 has the collar assy so its a bit easier.

 

[BugEyes]

Re: Yam 90 2-st 99 impeller change

Thank's<br />I will get the parts and do it the coming weekend

 

[mattdd]

Re: Yam 90 2-st 99 impeller change

wow. saw this just in time. iam hung up on getting the key outta the shaft. waiting till tomarrow to take the torch to it. i have a 90 as well. its an '86. my pump cover and assembly dont look quit like the one in the link. my plastic cover and the metal "drum" that the impeller rides in are connected....should they be? i also dont have the 2 piece collar holding the drum on. i just lifted the cover off, and impellar and everything came with it. my motor blew and the shop said the pump is why it blew. motor is back together, and now that i have the pump apart the impeller is really tight in there, to the point where the blades have to bend to fit. is the the correct way/part? if it was already this tight and it dosent look like the key was slipping, how did this cause my motor to overheat....or in otherwords how do they fail?<br /><br />thanks

 

[BugEyes]

Re: Yam 90 2-st 99 impeller change

When they fail it's normally the rubber impeller that breaks down, looses the blades/paddles and leaves only the center part. Alternative is the half moon key to make it spin on the shaft but I have never seen that. Another possibility is that the hard center part in the impeller is loose from the rubber and spins with the shaft without spinning the rubber impeller itself.<br />A new impeller is normally tight in the housing to the point where the blades bend slightly.

 

[mattdd]

Re: Yam 90 2-st 99 impeller change

i dont have any of those problems. my blades are still there and fully intact. the key hasnt slipped, and iam pretty sure the center didnt break away. but my blades are probally 1/4" larger in dia. then the metal housing. they really have to bend to get in there. i guess this is why it failed, right? wrong part maybe. but i ran it for over a year and a half, with no problems, maybe it just decided to lock up???? idk. <br /><br />thanks

 

[BugEyes]

Re: Yam 90 2-st 99 impeller change

If the hub is not spun and the key is intact it will rotate if the engine is running. It's on the driveshaft and just can't stop any other way.<br />Did they not already change the impeller at the shop where they said it failed?

 

[mattdd]

Re: Yam 90 2-st 99 impeller change

I don’t think they checked it back then. It was more of a “your motor is blown, it probably happened cause your impeller went out and it overheated” type thing….I think,….. that was back in Nov. My father in law rebuilt it for me, but he doesn’t really know much about boat motors, all he did was rebuild the powerhead. I am thinking it must be something else. But it definitely overheated causing the middle cylinder melted on top and broke apart on bottom. Thanks.<br /><br />ill see if i can get some pics tonite

 

[mattdd]

Re: Yam 90 2-st 99 impeller change

sry for the bad pics. but, is this what it should look like on an '86. seems like its really tight.<br /><br />

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<br /><br />also my key didnt come out at all. i left the whole lu at my bro-in-law so he can continue to grind away at it. iam guessing that a new one dosent come in the impellar kit, so what size do i need to get to replace?

 

[BugEyes]

Re: Yam 90 2-st 99 impeller change

You better look for other problems before you start that engine up again. That water pump doesn't look broken to me.<br />The bend on the blades look a bit much but I have not yet seen the 90 hp pump inside, will this weekend as I bought a new impeller. Can take some pics of it if you like.

 

[rodbolt]

Re: Yam 90 2-st 99 impeller change

the cup looks worn and the impeller is taking a set but I dont see an overheat, I just see normal wear.<br /> the key comes in the pump kit.<br /> you should have used a dull chiesel to remove the key.<br /> overheat normally starts smoking #1cyl first. the middle usually smokes due to carb or fuel pump problems. the kit will come with a new cup,plate,impeller,gasket, key and bolts.

 

[BugEyes]

Re: Yam 90 2-st 99 impeller change

Changed mine today and it looked just like yours except less worn. Acually I could have skipped the change but I had no way of knowing that as the engine is new to me.<br />Gave it new plugs and new gearcase oil as well, no water at all in the old oil is a good sign.<br />The hose connecting in front of the pump ends in nothing, what is it for?

 

[rodbolt]

Re: Yam 90 2-st 99 impeller change

that hose is for a speedometer pick up.

 

[BugEyes]

Re: Yam 90 2-st 99 impeller change

Thank's<br /><br />That explains why it leads to nothing as I don't have a speedometer.

 

[jasell]

Re: Yam 90 2-st 99 impeller change

When doing this as part of the yearly service, should go for just the impeller or the complete pump-kit?

 

[BugEyes]

Re: Yam 90 2-st 99 impeller change

After talking to the Yamaha Centre in Stockholm I did just the impeller.<br />Boat is now in the water and runs fine,strong telltale sprout always present.