Mc1 won't pump water

[yjanray]

Any ideas why a freshly rebuilt water pump would not pump? I've put two impellers in and they keep burning up. No water flow through the transom or prop hub. Can't figure it out. Boat is hooked up to muffs with full water flow.
thanks

 

[Bt Doctur]

Remove the top cover, impeller and gaskets and look to see if the base gasket is not reversed cutting off the water into the bottom of the pump base.

 

[yjanray]

Remove the top cover, impeller and gaskets and look to see if the base gasket is not reversed cutting off the water into the bottom of the pump base.

I checked that. You mean the hole on the bottom of the water pump base? The gasket isn't covering any passages.

 

[Bt Doctur]

Its only 5 inches or so from the inlet holes to the base of the pump, you got to get water to there so you cant be melting the impellers. If you mean your melting the upper cover then you may have missed the copper water tube going into the plastic guide tube. Other than that the hose has come unattached from the gimbal housing or the transom side.

 

[yjanray]

if the pump is pumping water, but it is plugged somehow, either a clog in a passage way or the tubing from the bell housing to the transom housing is blocked, would that cause the impeller to burn up, since the water its pumping has no where to go?

 

[Bt Doctur]

What part of the pump is burning up?
Remove the inlet hose from the therm housing and give it a quick run test. Good water in then you have a restriction of the water out. plugged manifold(s) pluged riser(s) No water in means something from the impeller upward

 

[yjanray]

What part of the pump is burning up?
Remove the inlet hose from the therm housing and give it a quick run test. Good water in then you have a restriction of the water out. plugged manifold(s) pluged riser(s) No water in means something from the impeller upward

The impeller is toasted like it was running dry. The metal housing inside the cover had rubber stuck to it. I back flushed the intake line from t stat out of gimbal. Assembly. Also, flushed water through the upper housing. Not sure what else to do.

 

[Bt Doctur]

you have no water getting into the impeller then. So why not? Drop the lower and put muffs on it and see is there`s a leak or gasket issue. Only other way with a brand new impeller and poor water supply is to use hi rpm to collapse the hose, burn the impeller but you would still see some water exiting the motor.

 

[yjanray]

No Title

Picture of fried impeller. I will install a new kit and put the muffs on just the lower and look for leaks around gaskets?

 

[Bt Doctur]

Just incase your doing something wrong in assembly http://www.boatfix.com/merc/Servmanl/6/6C3R3.PDF

 

[Bt Doctur]

 

[yjanray]

Thanks for the great info BT Doctor. The first thing I checked what that picture, to make sure that the gasket was put on the correct way.

One note, when I took apart the water pump this last time, after I ran the boat for a minute, the gaskets were all wet. Do they usually get wet? I didn't notice any water in the copper tube or anything like that.

 

[Bt Doctur]

Think of the pic as a clock, at 3:00 is a small slot.This is a drain for water in the pump. That why you never find water in the copper tube

 

[yjanray]

No Title

Think of the pic as a clock, at 3:00 is a small slot.This is a drain for water in the pump. That why you never find water in the copper tube

Ok I've found two things that I believe are not right. This lower unit is a new to me unit, just an fyi. So the relief port at the bottom of the lower unit opposite of the drain plug is completely plugged all the way up to behind the shift shaft. Isn't that port to help drain water from the water pump? Could that cause my problem?

Second, I was inspecting the bearing carrier and prop shaft seals and I think that the carrier is inside there upside down. Take a look at these pics and let me know. Could that lead to any problems with water pumping or just in general?

Thanks

 

[sogood]

A stupid thought but have you inserted the woodruff key on the shaft when fitting the impeller? If not, the shaft will turn but the impeller won't. just my 2 cents worth.

 

[yjanray]

A stupid thought but have you inserted the woodruff key on the shaft when fitting the impeller? If not, the shaft will turn but the impeller won't. just my 2 cents worth.

Thanks for the reply. Yes, I have made sure that they key is in place. the impeller turns I know that because after I run the motor for a minute to see if its pumping, it burns the impeller up. I've checked the water pump gasket to make sure its installed correctly, as well as all the other gaskets.

I am trying to clean up the passage in front of the shift shaft, which leads to the weep hole at the bottom of the lower unit, opposite of the drain plug.

 

[Bt Doctur]

I use a very long masonary drill bit and I`m VERY ,VERY CAREFUL. I have cleaned it down as much as possable and re-drilled the drain hole a bit higher

 

[yjanray]

Thanks. On a side note, I took the bearing carrier out, and the reverse gear and bearing stayed inside the housing, it separated from the bearing carrier. how in the heck do I get that out?

 

[yjanray]

Figured it out. Just pulled the o ring out and just turned over and the gear fell out.

 

[yjanray]

Ok, so after cussing this water pump out for several weeks, cleaning out all the passages, changing the impeller twice and probing all the water cavities and just general staring at the lower unit for hours on end, I finally decided to turn elsewhere. So I figured out why the drive wasn't pumping water.

The muffs were not tight enough on the water intake, so water was coming through both intakes, like I usually check, but when I put it on muffs with the lower split, I noticed that water was not making it up to the water pump to prime the pump....I bent the metal on the muffs so they were touching each other and putt if back on the drive. turned the water on and water was shooting up the water pump and priming the pump. So it turns out this entire time, it was my muffs that were the problem, and nothing to do with the water pump impeller.....

Biggest DOH! in the world.....but glad I figured it out.