is my water pump working?

[woodward407]

I just bought an older mercury ob motor it’s a 20hp. I have never owned an ob before and was checking it out. How do I check and make sure the water pump is forcing water to the engine. I stuck the motor in a barrel of water and cranked it up. Is there supposed to be water squirting out of a small hole on the left side of the motor facing the motor from the front? Will it squirt out instantly or does the engine need to heat up first. I ran it for about 3 minutes and all that came out of the hole was a little vapor like steam. Any help will be most helpful.

 

[tashasdaddy]

Re: is my water pump working?

how long has the engine been sitting. the answer is yes, should start within a couple of seconds after start. coulb be insects have moved in there. weed eater line works very well to clean it out. then if no water, time for and impellar, if you don't know the last time it was changed change it anyway. cheap insurance.

 

[studlymandingo]

Re: is my water pump working?

Like tashasdaddy said: Change it! Instead of speculating whether or not the pump is good, replace the impeller. It is not expensive, and if the one in there has any age, it won't last too long if it is working at all.

 

[woodward407]

Re: is my water pump working?

Thanks. I will change it to be safe, now I have been a mechanic for years but never changed an impeller before can some one give me the highlights to changing the impeller I don’t really want to buy a repair manual unless I absolutely have to there expensive.

 

[j442w30]

Re: is my water pump working?

If you plan on working on an engine its imperative that you have the manual. Don't buy an aftermarket one like clymers or seloc get the factory one, you won't regret it the first time you need it. To change the impeller remove the lower unit and remove the nuts that hold the pump housing around the drive shaft. Remove the housing and you will see the impeller. The impeller slides off the drive shaft make sure you keep the key that holds it on the shaft. While you're at it inspect the rest of the water pump pieces like the metal plates and other gaskets.