Water Pump Mystery - Running out of ideas

[Clucas]

De-winterized my late model raw water cooled Atomic 4 this weekend which included replacing the impeller. When I removed the WP cover, I had the expected gush of antifreeze which protected the engine over the winter. With my other spring commissioning tasks complete, I started her up, attempting to pull water from 5-gallon bucket as I do at the end and start of each season.

The engine started right up. Once she started, I dropped into the cabin to stick the hose into my 5gal bucket and went to the stern to check for water flow -- nuthin… waited a bit longer… not a drop, so I shut her down.

Sip of coffee, started her again and checked for suction at the end of the hose in the bucket. Nope.

I started diagnosing from the pump end…
WP cover had a brand new gasket and was screwed down firmly -- no leaking. I pulled the impeller and shaft out -- impeller was oriented properly. I wiped the end of the shaft clean and marked a vertical line with a Sharpie marker to verify that it was in fact rotating. Put the cover back on and started her up for no more than about 20sec. Opened up the water pump and found the impeller in the exact same orientation -- my vertical line was still vertical suggesting the impeller/shaft may not be rotating ?!? I've done this three times (once with a different impeller and shaft) and have have had the same result -- index mark on the WP shaft suggests it's not moving and no discernible suction on the bucket end.

So here's where I'm at… engine runs really well. Accessory drive is turning (engine wouldn't run without it, right?), distributor is doing it's thing (of course) and alternator belt is turning, A buddy suggested that possibly, the impeller is turning, but stops in the same place because the engine is stopping at the end (or start) of a compression stroke. Thoughts? Does this make sense?

Hopefully not related… when I crawled into the lazerette to change the impeller, I found a nut and lock washer laying in the engine compartment near the accessory drive. For the life of me I can't figure out where they came from (the nut is for a 1/4" bolt). My engine compartment is clean -- I noticed it right away. No idea it it's related, but can't help but think it might be. All I do know if is that I had no issues when I winterized the engine in the fall -- the engine sounds great and starts right up.

Planned next steps… I plan to use a remote starter to bump the engine with the WP cover off to see if it does rotate. If it does move, I'm going to try removing the hose upstream of the pump from my Groco strainer and manually prime the pump (I've never had to do that before, but I'm getting desperate). The Groco strainer is higher than the water pump and the water intake is lower than the strainer, requiring the water pump to pull up from the intake. Would be great if it's something stupid like it needs a better prime. If my test with a remote starter shows that the impeller does not move... I'm kind of at a loss. Anyone encounter something like this? No weird noises from the accessory drive.

Insights? Thoughts? Running out of ideas fast.

[ndutton]

Actually your buddy's supposition is a quarter right and may have more merit than at first blush. With a vertical line on the shaft end it could be stopping on any of four compression strokes and the line would still be vertical assuming it was on a compression stroke (likely) when the line was drawn.

I agree with you. Since there is a suspicion the impeller is not turning you need to confirm it before proceeding. Following that, attempting to prime is the next logical step and disconnecting hoses one at a time along the water path for testing follows.

Don't forget about the impeller thickness discrepancy that emerges from time to time.

[Mo]

Agree with Neil.

[Clucas]

Actually your buddy's supposition is a quarter right and may have more merit than at first blush. With a vertical line on the shaft end it could be stopping on any of four compression strokes.

I agree with you. Since there is a suspicion the impeller is not turning you need to confirm it before proceeding. Following that, attempting to prime is the next logical step and disconnecting hoses one at a time along the water path for testing follows.

Don't forget about the impeller thickness discrepancy that emerges from time to time.

Thanks, Neil. I dropped in my spare impeller that I know has worked in the past. Both are identical in thickness and yielded the same result. As with any diagnosis, it's a process of elimination. Any thoughts/suggestions on starting places, if it turns out it's not turning?

[ndutton]

Any thoughts/suggestions on starting places, if it turns out it's not turning?

I'd say it's HIGHLY unlikely so let's not go there just yet. A functioning distributor and alternator pulley strongly suggests the auxiliary drive is fine and that's the same mechanism that turns the pump. If the pump is not turning the only thing that comes to mind is a damaged or broken tenon that engages the slot in the pump shaft and I cannot imagine what would have caused that. If memory serves, you'd be the first.

[Marian Claire]

With the water pump mounted and the cover off. Can you turn the impeller by hand? Or with the above and the impeller off can you turn the shaft by hand? Just trying to check the suggestions without removing the pump. Dan S/V Marian Claire

[tenders]

Under Occam's Razor we must first rule out the simplest explanation for the symptoms before ruling out the more complicated. I think an unprimed pump best explains this situation. However, as long as you've got the pump cover off you could prop up your phone just so, and take a movie of the impeller while you turn the engine over, to quickly prove or disprove your friend's theory about the impeller stopping in the same place every time.

I have an orange Home Depot bucket with a bronze hose spigot mounted at the base just high enough so that the spigot doesn't hit the ground when the bucket is on the ground. It's designed to be filled with water and placed on the edge of the cockpit seat, or countertop, with a hose led to the raw water intake (or a 12V pressure washer which doesn't work very well).

With this it's easy for one person to put a little positive pressure on the intake without putting street water pressure into the engine. I originally built this to assist in winterizing but I've always had a helper and never used it for that purpose.

[Skywalker]

My raw water pump wasn't drawing this spring. New impeller. Nothing.

Removed the output hose to check for prime and she started pumping.

I side with simple first. Prime the pump.

[Clucas]

Thanks for all responses. Stopping by the boat on the way home tonight to try priming the pump (never had to do that before, but it's possible I lost prime when I opened the strainer to clean the basket).

Will report results (fingers crossed).

[JOHN COOKSON]

+2 or +3 on the next step being to try priming the pump.
I presume your boat is in the water.
If the prime doesn't hold you can get rid of the blockage in the plumbing to the exterior of the boat by removing whatever tube is on the pipe now and putting a new tube on the pipe - I like clear plastic - and supporting it upright, cut it off just above the waterline, and run a long screw driver or piece of rebar down through the open ball valve.

TRUE GRIT

[sastanley]

I have an orange Home Depot bucket with a bronze hose spigot mounted at the base just high enough so that the spigot doesn't hit the ground when the bucket is on the ground. It's designed to be filled with water and placed on the edge of the cockpit seat, or countertop, with a hose led to the raw water intake (or a 12V pressure washer which doesn't work very well).

With this it's easy for one person to put a little positive pressure on the intake without putting street water pressure into the engine. I originally built this to assist in winterizing but I've always had a helper and never used it for that purpose.

tenders, this is one of the most simple and absolutely brilliant ideas ever.

I'll go with, 'the pump lost prime when you splooshed out the antifreeze for $600, Alex.' - I use a clear braided hose for my bucket feeds and I can see if the pump is pulling water over the hump.

However, now I am going to install a male 3/4" hose fitting on each end, one for my 3-way valve just before the pump, and one for my new (probably not orange) bucket with a spigot up about 6" on the side!

[marthur]

I use the bucket idea too, but my valve is as close to the bottom as I could make it. That way i can completely empty the bucket. It also has a dedicated piece of hose attached to the ball valve. Here is a handy use for it: after removing the winter antifreeze, I use the bucket to fill jugs for storage or disposal. No spills!

[tenders]

> my valve is as close to the bottom as I could make it.
> That way i can completely empty the bucket.

This exactly. I'd love to patent this concept and make people pay me five bucks every time they rig a spigot to a bucket, but I'm quite sure I didn't invent it.

My boat is on a mooring, and another use I have for the bucket is to fill it with fresh water on shore to replenish some of the water in the boat's FW tank. It's a lot easier to let gravity draw the water into the tank fill through the spigot than it is to maneuver a bucket over a funnel, or to drag a whole bunch of one-gallon jugs out to the boat.

PS: Shawn, I think you need a FEMALE fitting on the hose connecting to the bucket spigot unless your plumbing follows an alternative lifestyle. Not that there's anything wrong with that but it will probably leak.

[edwardc]

> my valve is as close to the bottom as I could make it.
> That way i can completely empty the bucket.

This exactly. I'd love to patent this concept and make people pay me five bucks every time they rig a spigot to a bucket, but I'm quite sure I didn't invent it. ...

Doesn't matter any more. On March 16 this year, the U.S. switched from a "first-to-invent" to a "first-to-file" system. So, go for it!

[Administrator]

I have seen a variation on this theme, wherein a length of hose was attached to the spigot, with a conical brass piece on the end. Picture a megaphone, with the mouthpiece on the end and the larger diameter attached to the hose via some sort of adapter. The mouthpiece end is sufficiently small in diamater, such that it can be jammed into a hose without leaking.

In practice, for example, the water hose for an AC system is disconnected at the (closed) seacock, the tapered end of this contraption is jammed into the hose, and antifreeze is drawn in from the bucket, through the pump, the AC unit and out the side.

Later, when the boat is pulled, the seacock is opened and the raw water allowed to drain out.

Bill

edit: I just found the makins' of such a system (called a flush bucket or something like that) on Grainger or Mcmaster-Carr. I forget which. Everything but the megaphone, but the cost was over $50. Geez!