Test Water Pump ?

[BigBand]

I'm working on a 1996 25hp Johnson outboard that I recently bought. No stream of water coming out the tell tale.

The motor ran great on the muffs when I ran the motor before purchasing it. I got it home and finally put it on my boat. Took it to the lake and no tell tale stream.

I've just replaced the water pump and reassembled. The original impeller looked and felt pretty good, but it's cheap insurance, so I put in the new one. I didn't see anything out of the ordinary when it was apart, other than a little corrosion due to limited salt water use. While I had the lower unit off, I put compressed air up into the water tube (water pump outlet tube) and I could hear it coming out of the tell tale. After reassembly, I ran the motor on the muffs again, and it still won't pee!

I think I need to divide and conquer, so I'm wondering how I can test the water pump. If I submerge the lower unit in a bucket of water so the water inlet is under water, wouldn't it work to turn the drive shaft with an electric drill and see if water is shooting up out of the water tube?

If this works, what else could it be? The schematic drawings show the tell tale in front of the thermostat, so that shouldn't be an issue. I doubt there's enough corrosion that water passages would be clogged, but I suppose that's a possibility. I've heard of a corrosion cleaning solution I could use - anyone know anything about it?

I need some net.wisdom !

 

[flyingscott]

When you put the lower unit back on did you get copper tube lined up with the housing. Did you put the key in the waterpump impeller.

 

[BigBand]

When you put the lower unit back on did you get copper tube lined up with the housing. Did you put the key in the waterpump impeller.

Yes to both questions.

I've also confirmed that the water hose to the telltale is clear. I pushed some nylon string trimmer line all the way up it.

 

[flyingscott]

Take the thermostat housing off and start the motor in water or on muffs see if water comes out.

 

[oldboat1]

agree with all, but is the motor overheating? burn your hand when you touch the top of the head?

t.stat and housing is suspect in salt water motors. Shouldn't minimize possibility of salt corrosion as it doesn't take much. I check t.stats by microwaving a cup of water to 140F, and dip the t.stat. Also need to check the housing for bypass blockage -- water should flow during warmup.

I've read here of Salt Away (think that's what it's called), but don't have personal experience with it. Some fresh water flushing may be enough, but you also may have to scrape out the passages under the t.stat cover or head cover. If you remove the t.stat, try flushing down from there -- can't hurt, and might help.

[edit. have a mechanic friend who tests thermostats by just heating the sensor with a torch.... If you have some evidence of corrosion, usually best to just replace it.]

 

[BigBand]

I only ran the motor for 30 seconds at an idle before shutting it down. Didn't check the head temp.
I can easily check the thermostat. If the bypass is plugged, why would I hear air coming out of the
pee hole?

Thanks for the ideas - keep them coming!

 

[oldboat1]

Check water circulation route for your motor -- tell tale likely ahead of the t.stat. Pull the l.u. and flush up the water tube.

 

[BigBand]

OK, finally got back to work on the 'fun things'.

I took off he cylinder head cover and then removed the thermostat. It seems to be free to open, although I'm going to replace it due to corrosion deposits and generally being conservative. Seems to be considerable corrosion deposits in the water galleys.
I ran the motor with the thermostat and cylinder head cover removed, holding my hand on the had to feel for heat. I'm supplying the water pump with water via the ear muffs. after running for about a minute, water began to come out of the telltale as well as out of the thermostat cavity!

Maybe I just didn't wait long enough in my initial run up !?

So, there's still more corrosion than I'm wanting, so back to some kind of cleaning. I took a look at the 'Salt Away' product - it seems to be for periodic flushing to prevent corrosion. Is it useful for actual cleaning? Maybe I'm being to anal about this?

Any other procedures or products for cleaning existing corrosion deposits?

 

[racerone]

One minute is way too long for water to start pouring out of the motor !!!