New impeller, not pumping water

[SC_Regal]

Was performing some maintainance on my 2000 5.0 EFI Alpha I Gen II. Replaced impeller - old one not in bad shape. Since I live where there is alot of sand and mud I flushed motor at both sides of thermostat housing. At first, I was unable to back flush, after some effort was able to back flush on the intake side and I flushed for several min. Last PM I had good water flow on the ear muffs, checked again today prior to dropping in the water and no flow noted. At first I did not see water from the transome so I disconnected the intake (port) side of the T-stat and no water at idle or low RPM, with some throttle (in Nuetral) I did get some sporadic flow. I just re-read the manual and other than not using Permex (I did use perfect seal) I followed directions and I think everything was installed like diagram.
Any thoughts? Thanks Mike

 

[dubs283]

Re: New impeller, not pumping water

I would first check to make sure the water transfer tube between the drive and transom plate is not kinked. This does happen on mercruisers and can cause major water flow issues. Also did you make sure you installed a new o-ring on the bell housing at the water passage? this can cause water flow problem as well.

 

[SC_Regal]

Re: New impeller, not pumping water

Yes, I did replace the o ring. I will pull the lower unit and check the tube.

 

[milkyway]

Re: New impeller, not pumping water

You did not forget to use the key lock? This is the only part that makes the impeller spin with the shaft. Without this installed, you will have no flow. Are you also sure the impeller's wings are in the right direction?

 

[SC_Regal]

Re: New impeller, not pumping water

No, I didn't forget the key.

I was wondering- I never back flushed the system with the outdrive off. Do you think that debris could have been flushed back into the outdrive, then when the impeller worked yesterday the debris could have been forced or lodged into the the cooling system on the intake side? That is what I'm going to try first. I plan to remove the lower half of the out drive, check the intake tube, then back flush the system. I will of coursr re-check the impeller and the gaskets to make sure all is correct. Any other thoughts?

 

[milkyway]

Re: New impeller, not pumping water

it's a very short distance from the tube to the wall of the outdrive, and from transom to the thermostat. when you flush, from either direction, you will know with certainty if all is clear. when you inspect the impeller's installation, also spin the shaft, where the impeller is installed with the key, and see if it will spin, and in the correct direction. also, if you have the impeller "housing" in your hand and turn it over, looking down so that you are looking at the the impeller, the tips of the impeller should be pointing clockwise. just double check.

 

[tic]

Re: New impeller, not pumping water

Mine has acted mysteriously ever since one impeller failed and a new one was installed..I've flushed it and when I remove the input hose to the T-stat I get good water flow.... On the first start of the day the water temp climbs rapidly then suddenly goes down but not until almost pegging out... Higher rpm's on the start up seem to help.. I also noticed yesterday after having the outdrive raised for an hour in the lake, it ran hot again once I restarted it.. I think that tube may be kinked in mine...Raising the outdrive kinks it..

 

[milkyway]

Re: New impeller, not pumping water

it cannot be kinked by moving the outdrive.

but when you run it on muffs, lower the outdive as low as possible so you don't make the ujoint work too much. from what i read, this is how you break the joint. and also the same reason why you have the trim limiter. i always lower the front of the trailer so i can lower the drive as much as possible.

 

[SC_Regal]

Re: New impeller, not pumping water

The more I sit here and search other posts, the more I am convinced I have some debris somewhere. I will thoroughly inspect everything.