1994 75 hp yamaha overheating

[grinder67]

My 1994 75 yamaha is overheating after running at idle for around 2 minutes but doesnt overheat at high rpms after running for more than 5 minutes. The water stream seams to be a little weak at idle but not sure if this is normal or not. I think its a weak water pump but looking for some input from someone who knows more about outboards than me.

 

[jeffersondodson561]

Re: 1994 75 hp yamaha overheating

When was the last time impeller was replaced?

 

[jiggin joe]

Re: 1994 75 hp yamaha overheating

While you are at it ceck/replace the pressure control valve. The grommet can go bad on them. I am assumiing your motor has one but check parts list to be sure.

 

[grinder67]

Re: 1994 75 hp yamaha overheating

I dont think the impeller has ever been replaced. But thats where i plan on starting. Thanks for your help.

 

[grinder67]

Re: 1994 75 hp yamaha overheating

While you are at it ceck/replace the pressure control valve. The grommet can go bad on them. I am assumiing your motor has one but check parts list to be sure.

Im not sure what the presure control valve is or where its located but i will check into it. thanks!

 

[1978skitender]

Re: 1994 75 hp yamaha overheating

While u got the tailpiece off, go with a wire into the watertube and flush it with water afterwards to make sure there is no dirt in it.

 

[icepaq22]

Re: 1994 75 hp yamaha overheating

had a similar problem with my 95, changed the impellar and the problem went away

 

[grinder67]

Re: 1994 75 hp yamaha overheating

removed impeller last night was missing the ends off of three of the six fingers! orderd a new one but a little concerned aboat where all the debris from those three fingers whent.

 

[99yam40]

Re: 1994 75 hp yamaha overheating

And you should be.
hope you will not have problems from them blocking off some cooling passages.
Good idea to pull thermostats and flush everything while lower unit is off.
And make sure the thermostats are functioning properly by testing them

 

[grinder67]

Re: 1994 75 hp yamaha overheating

I have already checked and made sure the thermostate is working properly can i just run water in the thermostate hole or is there some other way i should flush the engine?

 

[99yam40]

Re: 1994 75 hp yamaha overheating

Hooking up hose to water pump outlet pipe while lower unit is off and stat is off will allow water to flow and from other way may or may not , but it is the best you can do with out dissembling motor

 

[grinder67]

Re: 1994 75 hp yamaha overheating

hooked hose to the water pump outlet pipe and with very little presure water started flowing out the pea hole. Does this meen i should be ok and dont have any obstructions?

 

[99yam40]

Re: 1994 75 hp yamaha overheating

All you can do is hope and keep an eye on things

 

[grinder67]

Re: 1994 75 hp yamaha overheating

I know there is a considerable amount of rubber missing off those impeller fingers, where else could they have went other than up in water passages where they certainly will cause cooling problems? Also i know im not the first person to have this happen so what are my odds that im gonna have trouble?

 

[grinder67]

Re: 1994 75 hp yamaha overheating

recieved and installed new impeller friday put boat on the lake saturday and everything worked great! ran boat for several hours no overheating, pump seamed to work better than when i first bought the boat. i wanted to thank everyone for there help! Thanks