Water pump pressure challenge!!!!! Help!!!

93 9.9hp 2 stroke

Replace gaskets and impeller with new one. Turned shaft by hand when bottom housing off and hear a pop pop noise as impeller turns. The key and washers were replaced

I took the thermostat out and not water is being pumped out!! Check to make sure tube was in tube guide


I am stumped. Any suggestions would be greatly appreciated

Hope some one can help out

Thanks

Re: Water pump pressure challenge!!!!! Help!!!

The 9.9 Mercs have two diffrent inside ID impellers. There is a good chance that the one you put in is of the larger ID and you need the smaller one to fit the DS and not slip on the key. The best way to find out is to drop the LU and mic the DS and the ID of the impeller you put in. More tha 5 thousdths diffrence betweem will tell the story. If you still have the old one slide it on a large Sharpie marker and then see if the new one goes on the same marker the same distance or if it goes on quit abit ferther. That way you can take the old impeller and the Sharpie marker and get the correct impeller needed. JMO
Oldman570

Re: Water pump pressure challenge!!!!! Help!!!

oldman570 said:

The 9.9 Mercs have two diffrent inside ID impellers. There is a good chance that the one you put in is of the larger ID and you need the smaller one to fit the DS and not slip on the key. The best way to find out is to drop the LU and mic the DS and the ID of the impeller you put in. More tha 5 thousdths diffrence betweem will tell the story. If you still have the old one slide it on a large Sharpie marker and then see if the new one goes on the same marker the same distance or if it goes on quit abit ferther. That way you can take the old impeller and the Sharpie marker and get the correct impeller needed. JMO
Oldman570

Click to expand...

Many thanks for the quick reply!

I did measure drive shaft and the inside diameter of the impleller and it's same measurement. I even compared it to the old one as I kept it and everything is the same.

I even blew air pressure through syphon spout by prop and check air coming out it the housing of thermostat(with thermostat removed)

Does water only exit spout by thermostat or from other ports. If thermostat is in the engine needs to heat up before water dribbles out of it.

Is there a special way that the impeller needs to be installed and direction fins are to be curved towards?

I wish I could figure this out with everyone's help

Thanks

Re: Water pump pressure challenge!!!!! Help!!!

The DS needs to be turned clockwise as the pump housing is being pushed down onto the impeller to have the veins going in the right direction. If not the veins could be going backwards and will not pump and might be the cause of the noise as they snap over center in the correct position. When testing in a barrel the water level has to be about 6" above the cavation plate on the LU for the pump to work. Pumps have to be below the water inorder to work as they are not self priming. Water should come out the tell tail fairly quick as it is plumbed into the sustem before the stat and some should flow out the exhaust ports on the midsection till the stat opens and lets water flow out the prop center.
Oldman570

Re: Water pump pressure challenge!!!!! Help!!!

The 9.9 Mercs have two diffrent inside ID impellers.

Click to expand...

That only on the 70's 9.8 (110) model.....

Re: Water pump pressure challenge!!!!! Help!!!

Hello to every one and those interested.

Thanks to who have provided great inside.

Resolution/Fix to my issue:

1) The water pump adapter guide need to be replaced.
2) Water Tube (Copper one) was to short for the adapter plate that was in the motor. Made my own copper water tube using 5/16" O.D with a 1/4" I.D (This was the original diameter of the old one.), used my trusty tube bending tool and made the appropriate bends and then my Flaring tool on the end going into the exhaust adapter plate.
3) Put "O" ring on bottom end of water tube to make a good tight seal in the water tube guide on the water pump.

Now have solid connections and good water pressure and flow.

****Not a hard job once you put your mind to it. Will be a bit challenging for the novice.

Thanks again to everyone and hope this will help others.