TOPIC: Water not pumping - '59 35 hp

Put a new impeller in over the winter, (old impeller didn't look bad but wasn't moving much water). Started it up in the tank today and it's still not pumping water out the water outlet.
Pulled the thermostat out in case it was stuck but still nothing. I had checked the water tubes with a bore scope while I had it apart and everything was clear. What am I missing?

Is it possible the impeller put in with vanes wrong way? I have seen that before.

Anything is possible. This is a picture of the old impeller. I put the new one in the same way. Manual says rotation should be clockwise, which this one would be when you flip it right side up.

Notice some vanes turned wrong on old unit. When I install, I make sure to turn the drive shaft clockwise (as manual suggests while seating to make sure they go in the correct way and don't get pinched.

Yeah, I was trying to figure out how they did that. I made sure I had all of the vanes going the correct way.

It only takes a secong to screw it up when putting the lower unit back on -- if you turn the flywheel the wrong way to align the splines you turn the vanes backward as they catch on the housing.

While I had the thermostat out, I noticed a very fine screen filter in the tube directly below the thermostat. Is there supposed to be a screen there? Is it possible that I've got a sediment clog right there?

What does 39 thru 41 do? Bottom of 42 is where I saw was a screen or clog.

Trying to make sure I understand the system. Assuming that the port on the side of the left tube is water inlet, valve on bottom of left tube is for bypass until thermostat opens, and tube on right is water outlet. Am I correct?

If I pour water down the left tube I can hear it running down the inside of the motor, so I assume that rules out a blockage. Back to the pump maybe.

is there a rubber grommet under the powerhead where the water tube comes up to the block.. i know on a newer motor i have now.. it had the same problem.. i picked it up cheap because the owner couldnt get it to pump water.. pulled the powerhead and the rubber grommets that sealed the water tube to the powerhead were melted closed..

I have had issues with these not wanting to pump water in a barrel. The exhaust stirs up the water so much that it'll suck air and the pump won't prime.

A good way to check for that (and a blown head gasket while you're at it) is to remove the thermostat and leave the thermostat cover off while you're starting the motor.

If no water comes up out of the hole, you've got impeller issues or other problems down below.

If you get a good flow of water, while the engine is still running hold the thermostat cover tightly in place and see if you start getting water out the exhaust relief.

If so, likely it's just a no-pump-in-the-barrel issue.

Note that if you try this and get water pumping thru the exhaust relief, but the engine starts to run poorly, you very likely have a blown head gasket.

What happens is, the combustion pressure leaking past the jacket into the cooling system pressurizes the system and the pump cannot overcome the pressure.

Buy pulling the thermostat cover, you relieve this pressure, and if the impeller & the rest of the water supply system is good, you'll get water pumped up into the powerhead. Then when you hold the 'stat cover down, there's enough water flow/pressure already established to get water sucked into the bad cylinder.

HTH & let us know what happens............ed

Happy Anniversary to the U.S.A. as well!!!!

When doing a impeller, simple put after greasing the blades and body, put the impeller on over the key, then turn the body COUNTER CLOCKWISE over it and bolt it up. Can't go wrong that way direction. I try to not turn the shaft as splines are in line the block so goes in easier.

Pulled the water pump apart and apparently the key slipped out of the impeller the first time I assembled. Rookie mistake I guess. Put it back together and it's pumping fine now.

Next question, I noticed some water leaking from above the water outlet near bottom of thermostat tubes and bottom of cylinder head. Is this normal, minor, or major.

Hard to tell in the pic, maybe it's the core plug at the bottom of the head leaking?

If it is, you can pull out the old plug and replace, the part is still available.

Here's some on eBay for under $5 each shipped:



It might help to wipe dry the area then see if you can pinpoint the leak, if it's not the core plug.

HTH.....ed

Thanks for the suggestion. It turned out to be leaking from under the power head. I had to pull the power head to replace a seal and I failed to finish tightening the rear two bolts when I put it back together. I'm really batting a thousand on this motor.