Need help finding a impeller seal/causing a cooling problem

[0352Marine]

I need help finding the impeller seal for my boat. Not the o-ring but the seal behind the impeller. I have a serious leak coming from behind the impeller. I replaced the impeller and o-ring thinking that was the problem but it was not. My problem is also heat related because when I am at idle for more than five to ten minutes the boat will start to overheat. At a cruisin speed of 15 to 20 mph it will cool off. I have also replaced the thermostat. I noticed that when the boat is cooled down and the thermostat is closed it starts to leak around the backside of the impeller housing (real bad like pouring water out). When it warms up and the thermostat opens it quits leaking all together, but it will not cool unless I take off. I'm thinking that when the thermostat opens it starts sucking air through the bad seal causing it not to cool properly at idle. Opinions??????? Any help would be greatly appreciated.

 

[SausageFingers]

Re: Need help finding a impeller seal/causing a cooling problem

The rear seal at the base (the one closest to the pulley), along with its sealed bearing, is one assembled unit and not available separately. You'll have to replace the whole pump with the pulley and they're $400ish retail, sorry. But hey... if it's 11 years old, it doesn't owe you a dime.

Speaking of 11 years old.... still running on original exhaust? If they're rusted closed the water won't be able to get out, the engine overheats, and that would explain the "thermostat closed --- water pouring out of pump" phenomenon.
A simple test: find the two hoses that run from the T-stat housing to the bottom of the manifolds. Undo the hoses at the T-stat, get a garden hose w/ spray nozzle, and try to force water through the manifolds. If it flows out the back of the boat just fine, it's not the exhaust. If you get soaked as the back pressure slams you in the face, the exhaust is wasted.
OR:
If the exhaust is free flowing... have you ever shredded a water pump impeller? If you didn't find all the little impeller arms, there could be one jammed in a crucial place.
Fixing that leaking pump is priority for sure though.

 

[0352Marine]

Re: Need help finding a impeller seal/causing a cooling problem

The rear seal at the base (the one closest to the pulley), along with its sealed bearing, is one assembled unit and not available separately. You'll have to replace the whole pump with the pulley and they're $400ish retail, sorry. But hey... if it's 11 years old, it doesn't owe you a dime.

Speaking of 11 years old.... still running on original exhaust? If they're rusted closed the water won't be able to get out, the engine overheats, and that would explain the "thermostat closed --- water pouring out of pump" phenomenon.
A simple test: find the two hoses that run from the T-stat housing to the bottom of the manifolds. Undo the hoses at the T-stat, get a garden hose w/ spray nozzle, and try to force water through the manifolds. If it flows out the back of the boat just fine, it's not the exhaust. If you get soaked as the back pressure slams you in the face, the exhaust is wasted.
OR:
If the exhaust is free flowing... have you ever shredded a water pump impeller? If you didn't find all the little impeller arms, there could be one jammed in a crucial place.
Fixing that leaking pump is priority for sure though.

Actually I went to David's Marine here in OKC and they sell the back seal so I lucked out and was able to purchase just the seal instead of the $400 impeller pump. So all you Volvo penta SX owners David's has the impeller seal for $8.99. I was so happy I was like now I can go to the lake this weekend. They just saved me almost $400. Thanks David's Marine.

I also replaced the impeller awhile back and when I replaced the thermostat I did find some impeller pieces from an old impeller. But the one I replaced had all it's fins still on it. I will try the water hose when I get home today. I had replaced the old riser gaskets with the new updated ones from the recall and I did not notice any blockage, but I will run a hose just to make sure. Thanks for the good tip SausageFingers

 

[Don S]

Re: Need help finding a impeller seal/causing a cooling problem

Those seals aren't hard to come by, see Item 5 in the link below which is here at iboats.
http://www.volvopentastore.com/Seaw...*****.197049694--store_id.366--view_id.768622

That seal probably won't fix the leak for long, when the seal goes, the bearings usually go to, or on the next trip.
Bearings have problems with water, it's a poor lubricant, and causes rust.

 

[0352Marine]

Re: Need help finding a impeller seal/causing a cooling problem

Those seals aren't hard to come by, see Item 5 in the link below which is here at iboats.
http://www.volvopentastore.com/Seaw...*****.197049694--store_id.366--view_id.768622

That seal probably won't fix the leak for long, when the seal goes, the bearings usually go to, or on the next trip.
Bearings have problems with water, it's a poor lubricant, and causes rust.

Thanks Don. I did spray it down with kroil and then pushed some grease on the inside of the seal (knowing that the bearing is sealed) and were it contacts the shaft hoping to advoid the inevitable which is kinda what I thought. When I spun the bearings they seemed smooth, but that does not mean anything. Well guess I better keep my tools onboard just incase.

 

[0352Marine]

Re: Need help finding a impeller seal/causing a cooling problem

I don't suppose I can press the old bearing out and replace it since noone has stated that.

 

[SausageFingers]

Re: Need help finding a impeller seal/causing a cooling problem

ohhhhh, I didn't realize that part was available separately. Thanks for the heads up