Sterndrive Impeller Question

sjp

New Member
Apr 18, 2012
13
Connecticut River
Boat Info
1994 Sundancer 300
Engines
Twin 350 Mercruisers w/Gen2 drives
I have a 94 Sea Ray Sundancer 300 with twin 350's and Mercruiser Gen 2 Drives. The motors have thru hull fittings that supplies the engines with raw water thru sea water pumps but only for exhaust as the engines are FWC. I removed the drives for service also to check gimbals, universals, and bellows. After separating the drives I noticed they still have impellers on them. Do I still need impellers on the drives?? The intake hose that would come from the drives are capped off inside the engine compartment.
 
is the hose between the drive and the gimble housing (outside the boat) cut or removed? if its not, i would reccomend it as the drive needs flow through cooling - no, you do not need an impeller
 
I will check on that. I want to say it's still connected as I remember a hose inside capped off by the housing where the water would come from the drive. I also remember someone telling me that the impeller and plate hold or should I say help hold the carrier seal in place.
 
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I will check on that. I want to say it's still connected as I remember a hose inside capped off by the housing where the water would come from the drive. I also remember someone telling me that the impeller and plate hold or should I say help hold the carrier seal in place.
The pump definitely does hold the seal in place, but doesn't require the impeller to do so. However, the outdrives do need cooling water running through them. It's surprising how much heat these things can generate. You mentioned "the motors have thru hull fittings that supplies the engines with raw water thru sea water pumps but only for exhaust as the engines are FWC". Something in that statement doesn't jive with me, as, even with heat exchanger, there has to be seawater coming from somewhere to carry off the heat. I assume with the thru-hulls that there's a raw water pump on the engine.
If no cooling water to the engine comes from the outdrive impeller, you still have to allow the impeller to pump cooling water through the outdrive. I can see that working by disconnecting the hose between the bellhousing and gimbal plate, allowing the impeller to dump water and keeping the outdrive cool. When checking the bellows, could you tell if that hose was intact? In stock trim, it runs alongside to the left of the bellows, then up to the top of the gimbal plate. It needs to either be cut, or removed completely.
 
Sorry, I knew what I was trying to write. Bad choice of words. Writing was always a weak subject for me. Yes the seawater does run through the exchangers and the raw water pumps are on the motors. Still have to run to the marina to check on the inlet hoses. Originally the reason for removing the drives nearing the end of the season I heard what sounded like a powersteering that was low on fluid noise (whine not a growl) coming from the outdrive or should I say from the outside the boat but only on 1 motor, even in neutral. I was expecting to find water intrusion, rusted u-joints and or gimbal but.... dryer than a nun's hoo ha down there. Also no water found in the gear oil, no metal shavings, and the upper gears look good. Currently the gimbals are greaseless and so are the u-joints
 
OK There are no inlet hoses. They must of been removed. I did not see a hose when looking behind the housing and I was able to turn the housing enough to get my finger on the side where the hose would be connected.
 
If you don't want to change impellers you'll have to add drive showers. I'll add those impellers are tough and long lasting so why not just change them every three years instead of annually? Either way you have to cool the drives.
 
I have changed the impellers and the carrier seals. It's not that I didn't want to change the impellers or skip out on PM, the question was more of did I still need them with the thru hull fittings supplying the water. My previous boats were through the drive so I'm like a virgin with the through hull set-up. From the responses I have received it appears the drives still need to be cool so thanks to all for your great input.
 

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