74 Merc 85hp Water Pump Problem

[HDWKING]

Ok..i Replaced The Water Pump Impeller Last Week. Put The Lower Unit Back Together. When Running On The Muffs Water Is Barely Pushing Out. I Am Getting The Water To Spit Out Of The Exhaust Port Though. Thoughts Anyone? Maybe I Should Try In A 50 Gal Drum To See If There Is A Difference. Everything Went Back Together Easy Enough When I Put The Unit Back Together Foward Reverse Neutral All Perfect.

 

[emckelvy]

Re: 74 Merc 85hp Water Pump Problem

Where is the water barely coming out, the telltale? That may be just a simple clogging problem. Blow it out with compressed air, run a wire up the telltalle/hose, or pull the hose off and clean it out.

If you're getting water spitting out the exhaust reliefs when you're on a flusher, that's a good amount of water flowing thru the motor. I bet there's a real good stream of warmer water coming out of the prop hub.

Feel the exhaust manifold (Port side, big flat cover) and it should be quite cool. If it's getting extremely warm while you're idling on the flusher, you're not "watering" the powerhead properly. If it's cool, you're probably OK.

If you do find you're having a circulation problem, pull the lower unit and make sure the guide tube on the water pump is in place and it catches the copper water tube as you're installing the lower unit.

Check to make sure the rubber water tube grommet is in the pump housing. Flow water up the copper tube and see where it all goes.

Cheers..........ed

 

[HDWKING]

Re: 74 Merc 85hp Water Pump Problem

THANKS ED. I PULLED THE LOWER UNIT BEFORE I SAW YOUR POST. I DID NOTICE THAT THE GUIDE TUBE OUT OF THE PUMP IS REAL LOOSE AROUND THE COPPER TUBE. AND THE WATER I SAW spitting out the exhaust reliefs looked like it was only spitting out the left side not the right? go figure. i put some blue rv around the copper so hopefully it will seal better with the guide tube and checked the new impeller just to recheck my work from the other day. i'll fire it up tomorrow on the muffs and see.

the rubber water tube grommet you mentioned, are you talking about the oring below the guide tube where it meets the pump? or below the entire water pump?

 

[emckelvy]

Re: 74 Merc 85hp Water Pump Problem

All the guide tube is for is to 'catch' the water tube on the way up. It doesn't do any actual sealing. It only guides the water tube into the pump housing where it engages that rubber grommet (yeah, it's a grommet not just an O-ring).

The rubber grommet is on the discharge side of the water pump and must be in there or you'll have leaks. Usually it helps to put a bit of grease on the grommet and on the end of the water tube, this makes them slide together better......ed

p.s. the RTV won't really do any good but it likely isn't gonna hurt anything, either, as long as you didn't get any in the end of the tube!