Would Bad Impeller Make Noise

[BobLuck]

I am hearing a noise coming from the backend of the boat both when it is in gear and out of gear. I am also noticing that no water is coming out from the back of the boat. The temperature will start going up past its normal temperature. This is an 88 mercruiser 4.3 and the impeller has never been replaced. This just started 1st time out this year. Would a bad impeller make noise?

 

[stonyloam]

Re: Would Bad Impeller Make Noise

If it does that is a BAAAAAD impeller. In either case it is about 15 years overdue. When you replace it make sure that all of the fins are there, and locate any pieces that are missing.

 

[cedarjunki]

Re: Would Bad Impeller Make Noise

I am hearing a noise coming from the backend of the boat both when it is in gear and out of gear. I am also noticing that no water is coming out from the back of the boat. The temperature will start going up past its normal temperature. This is an 88 mercruiser 4.3 and the impeller has never been replaced. This just started 1st time out this year. Would a bad impeller make noise?

im going to take a willlld guess and say that noise is probly the gimble bearing since the impeller was never changed i doubt the bearing was. what about bellows? were they ever changed? gear oil in lower unit???

ive pressed my luck with some really baaaaad ones and never heard them make noise. describe the noise maybe???


explain seeing no water out the back though..... is this in the water or on muffs??

 

[nola mike]

Re: Would Bad Impeller Make Noise

I am also noticing that no water is coming out from the back of the boat. The temperature will start going up past its normal temperature.

if it wasn't bad before, the impeller is certainly bad now. i would think that if an impeller was bad enough to cause noise, the noise wouldn't last for long until the impeller disintegrated completely, though i don't really know. either way, sounds like you need to replace the impeller/housing, inspect all plastic parts, check drive oil, pull drive and inspect gimble bearing and u-joints...

 

[BobLuck]

Re: Would Bad Impeller Make Noise

There is no water coming out around, what I believe is called the gimbal ball. I did start the boat with the muffs on before putting it in the water and I say water coming out. When I noticed the noise I put it on the lift with the lower unit down in the water, which is when I saw that no water was coming out now.

I drained the gear lube in the fall last year and replaced it with the High Performance lube like I do every year. I also had the lower unit off before last summer and greased the drive shaft. The noise is like a faint grinding sound. If does increase as the RPM increases while in gear. I believe also when it is not in gear but I don?t remember for sure.

 

[Bondo]

Re: Would Bad Impeller Make Noise

Ayuh,... At the very least, you otta pull the drive to check the gimbel bearing,+ u-joints, as that's probably the Noise your hearing...
And, while you're at it,...
Change out the Impeller,+ it's housing, it No doubt needs it...
You'll want to Backflush it, from the T-Stat housing back to the drive, while it's apart.....

 

[BobLuck]

Re: Would Bad Impeller Make Noise

Thanks everyone for the information.

 

[TilliamWe]

Re: Would Bad Impeller Make Noise

I'll say it's probably your exhaust shutters that you are hearing. No water going to the exhaust means that the rubber outer part of them has melted away and the metal remains are clanging/banging/clinking inside the y-pipe.
However, check the other items as described too, but I'd check the exhaust shutters (commonly referred to as "flappers") too.