is this what my impellar is supposed to look like?

[mattdd]

from my '86 90hp yamaha.....<br /><br />

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<br /><br />my motor melted, and has since been rebuilt DIY, the shop that originally looked it over b4 it was fixed said "it overheated....probally the impelllar went out". when i got to the impeller i was expecting it to look a lot worse. its still in good shap, the key didnt slip and it looks like it should be turning. does it look like it might be too tight in the housing? like it is the wrong part or something? it ran well for 1.5 years. if this isnt the prob what else could cause it to melt the middle cylinder? seems like if water was flowing it would be really hard to get that hot.

 

[Texasmark]

Re: is this what my impellar is supposed to look like?

Looks good to me with a slight set to the blades which isn't all that bad and I don't see any wear on the vane tips although the pic is a bit fuzzy.<br /><br />The impeller is a water pump delivering pressure to the powerhead. To get pressure you need a pump. To pump you need to compress the water. That is why things are shaped the way that they are and if you installed the driveshaft, you would find that the impeller is not centered in the waterpump housing; rather offset...eccentric. This is how you develop the pressure.<br /><br />Suggest you look elsewhere for your problem as I see none here. Liked cloged passageway into or outof the waterpump.<br /><br />Mark

 

[mattdd]

Re: is this what my impellar is supposed to look like?

that was what i was thinking too....a clogged passage way, where does the water come in at, thru the skinny plastic grates on the LU?

 

[Ray Neudecker]

Re: is this what my impellar is supposed to look like?

Yes it comes in through the grates mounted in the gearcase. If it only got one cylinder with no scarring on the others, a stopped up carb is a more likely guess as to the problem. Test the over heat sensor and buzzer, since an alarm should have sounded before the engine croaked if it was due to over heating.

 

[mattdd]

Re: is this what my impellar is supposed to look like?

somebody unplugged my buzzer, but i was wondering how to test that cause the wiring is a little melted. just put 12v to it? thanks for helping, i feel like we are getting somewhere. ill check carbs tonite and i have half day friday to work on it. wouldnt it be something to actually get to the lake this weekend.

 

[mattdd]

Re: is this what my impellar is supposed to look like?

what part of the carb gets stuffed up? i got the carbs off and they look really clean. is it inside the carb that gets clogged or some where along the injector?

 

[Silvertip]

Re: is this what my impellar is supposed to look like?

I agree with was probably a lean carb issue and not a cooling system problem. That said, as long as you have the water pump apart, replace it since you don't want this critical to be "used" when you have a "new" power head. Also you don't have an injector. Carbs get varnish and debris in the high and low speed passages inside the carb. You can't see those passages to clean them without complete disassembly, soaking in carb cleaner and then blowing them out with compressed air. They are then reassembled with new kits. Make sure float level is properly set before reassembly. Link&sync should then be done along with idle mixture and idle speed setting with the engine in the water -- not on muffs. If you don't have a service manual, get one. If you don't want to buy one, check your local library.

 

[mattdd]

Re: is this what my impellar is supposed to look like?

Thanks everybody. We ran the engine a couple times, and its missing on one cyl. one coil is weaker then the others, and we switched the coils around to determine that that was the case. So the new coil is on the way. It dosent seem like any of the carbs are running lean (of course that’s hard to tell with the one cyl missing), so I probally wont be dropping any more money on a carb rebuild right now. But just to give them a tune up, can someone tell me what the starting point is for air/fuel screw, and what the procedure is for adjusting the carbs? thanks