1972 Mercury 402 - r/r water pump impeller shredded

[twsmith54]

Getting this thing running still... I got it started but only ran for a second because no water came out the tell-tale. I went to replace the impeller and found the old one shredded. Just the center left, all the fins gone. What should I be concerned with? Where did the pieces go? Obviously up into the water passages. So, is there some kind of flush I can or should do?

 

[racerone]

Post compression test values.----The motor may well be ruined already.

 

[twsmith54]

That was the first thing I did before I bought the boat and rewired the engine. 150 psi in each cylinder.

 

[Scott Danforth]

find the other bits of the old impeller.

 

[twsmith54]

The impeller is obliterated. I'm curious what ideas people have about possible problems with the pieces and ways to possibly flush them from the engine?

 

[Scott Danforth]

The bits have to come back out the way they went in. Many cases that means pulling water covers

This is why it is recommended to change impellers every few years (before they fail)

 

[Chris1956]

Check under the wearplate for impeller bits. Try to reassemble old impeller with the bits, so you can see how much is still missing. You could try a backflush, via the thermostat opening, with the gearcase still removed.

Run the motor in a barrel of water, gearcase installed, with a rebuilt waterpump and see how she runs. A flusher device is not a good test for your issue, as you want the test to simulate actual operating conditions.

 

[twsmith54]

The bits have to come back out the way they went in. Many cases that means pulling water covers

This is why it is recommended to change impellers every few years (before they fail)

It's a project I picked up late last summer. I continue to find new problems. I'm getting closer to running it.

 

[twsmith54]

Check under the wearplate for impeller bits. Try to reassemble old impeller with the bits, so you can see how much is still missing. You could try a backflush, via the thermostat opening, with the gearcase still removed.

Run the motor in a barrel of water, gearcase installed, with a rebuilt waterpump and see how she runs. A flusher device is not a good test for your issue, as you want the test to simulate actual operating conditions.

Ok, thanks for the barrel advise. That makes sense. I can definitely flush from the thermostat. It is at the top and back of the head.

 

[jimmbo]

Or you can pull the Water Jacket Cover off the Block and take a look