My engine stopped pumping water during my first time out for the season yesterday. I shut it down as soon as I saw the high temp indicated. When I pulled the cover off the impeller housing, I found an impeller with none of the 6 blades remaining on it. Three of the six were in the impeller housing area. I removed them when I popped in the new impeller. Any suggestions on where to look for the other three? I opened the thermostat housing and diid not find any there. I removed the hose on the water pump at the exit side, thinking they may be in that elbow, this was not the case. I do not have a heat exchanger as this is a fresh water boat. Any chance these suckers went through the system and out the exhaust? Any chance they went out the intake through hole? If they didn't go out, they are in the system waiting to over heat my motor once again. I am sure I am not the first one to go impeller blade hunting on a 5411.
Missing Impeller Blades 5411 No Heat Exchanger
- Thread starter Blue Hull
- Start date
- Status
Stu,
Yes, only down stream. That being the case, where do they normally get stuck after going down stream of the impeller housing? Seems to me if they made it through the block they would not make it past the thermostat. When I opened the thermostat housing I did not find them on top of the stat. I removed the stat and looked under it and they were not there. My thinking is that someone may know where they ususally get stuck in a 5411 with the cooling system designed to run without a heat exchanger. In boats with heat exchangers there is a screen at the front of th heat exchanger intake and they are often found there. That info does not help me as my 5411 has no exchanger. lake water comes in via through hull fitting, up to inlet side of impeller, through block and out exhaust hose. There is a reciirculating circuit to help warm up the motor which is the circuit the thermostat is controlling.
Yes, only down stream. That being the case, where do they normally get stuck after going down stream of the impeller housing? Seems to me if they made it through the block they would not make it past the thermostat. When I opened the thermostat housing I did not find them on top of the stat. I removed the stat and looked under it and they were not there. My thinking is that someone may know where they ususally get stuck in a 5411 with the cooling system designed to run without a heat exchanger. In boats with heat exchangers there is a screen at the front of th heat exchanger intake and they are often found there. That info does not help me as my 5411 has no exchanger. lake water comes in via through hull fitting, up to inlet side of impeller, through block and out exhaust hose. There is a reciirculating circuit to help warm up the motor which is the circuit the thermostat is controlling.
The 5411 has a very long exhaust hose run & the impeller blades could be lodged somewhere within it or in the water muffler. I have the 5411 as well. I replaced my impeller last year. Hope this doesn't happen to me, but at least you caught the problem before it was too late. The only way to know if impeller bits are blocking coolant flow is to run the engine at the dock & watch the exhaust stream off the stern transom discharge. But beware that the 5411 doesn't really produce a constant water stream anyway, & it takes a while to discharge until the engine warms up, if you're using the thermostatically controlled coolant loop. I don't like to wait 5 minutes to see the water flow, which makes me nervous, so I rarely use the thermo loop.
Now I'm just thinking of what I would do with my 5411 in such a case...if no trace of the missing impeller blades showed up, and I was still concerned (not wanting failure 50 miles out), I would try a garden hose under little pressure and reverse the cooling system flow to see if they can be dislodged and come back out the impeller case. Certainly would not use high pressure, but a gentle backflow. Now what I am going to do is change that impeller. Good luck and let us know.
I would avoid trying to backflow a raw water cooling system by flooding the water muffler. If water fills the muffler completely & flows back to the exhaust manifold it will enter the engine & flood it, thereby destroying the engine by getting water into the motor via the exhaust stroke of the engine. That is a much more risky maneuver then to just leave the bits of impeller in the exhaust system, which are rubber & will float. They will most likely just float out of the exhaust on their own through the exhaust flow. They have likely already exited the water muffler & exhaust at the transom anyway. If you have raw water cooling visible discharge at the transom, then I wouldn't worry yourself about it. The important thing is that you shut the engine down & changed the impeller before it overheated & killed it.
It would seem that the obvious point of water insertion to gently reverse the flow would be at the exhaust elbow water injection hose, which would be disconnected from the downstream muffler and exhaust system. My concern about letting pieces of impeller simply pass through depends upon the size of the pieces and any potential narrowing of the cooling system like at the elbow injection site. The 5411 does not have much water flow in its cooling system due to the recirculation of water at the mixing T, and merely spurts water out the transom exhaust. In spite of its small size, the 5411 is depended on for safe passage, particularly where we sail in very isolated areas and out of sight of land. If I couldn't locate the missing impeller pieces, I would try to eliminate any possibility that they are going to lodge in the cooling system at a critical time. That little engine should run no warmer than 140 or so degrees so there are consequences running in 80+ degree water. The advice on filling the water muffler should cenrtainly be heeded when cranking the engine without it starting and blowing out the water with the exhaust. Again, this thread provides motivation to replace that impeller yearly.
I wold try back pressure on the 5411's two inch long hose where the engine feeds water to the manifold. I would also open the thermostat housing and see if any blades found there way into it.
Run the engine with the intake and return hoses going from & to a bucket and see if the flow from the engine looks healthy.
Been a while but happened to me. Irwin Shicks, bless his soul, for those remember him, suggested I look in the 90 degree pipe elbow. I pulled off the hose and found them stuck right were he said!
He was. mechanic from way back out of Mystic Port Conn. that helped me soooo many times. He did sub duty in WW2 and was awesome and passed a few years ago.
Past that I would sail on. Little bits of rubber should not shut you down.
He was. mechanic from way back out of Mystic Port Conn. that helped me soooo many times. He did sub duty in WW2 and was awesome and passed a few years ago.
Past that I would sail on. Little bits of rubber should not shut you down.
correction: Urban F. Shick
I knew him as his log on "QShicks"
Not WW2 but Korean War/vietnam war.
- Status