A/C pump lost prime?

Z-Worthy

Z-Worthy

Active Member
Jun 20, 2014
457
Sandusky, OH
Boat Info
2002 Sunseeker 44 Camargue
Engines
450hp Cat 3208s
I just launched this morning and so far the only thing I can't get working is my A/C raw water pump. It kicks on and spins but you can tell from the sound that it's dry. I have water pouring into the strainer, but a seemingly dry pump. This seems impossible to me. Could I be missing something? Shouldn't the pressure from the raw water be enough to push an air bubble through the system?

717c2eb2287f05cc61207a215fa95fe3.jpg
 
You do see that the through is closed, right?
 
Open the seacock and take the boat for a run. The force of the water running under the boat will force the air out of the system. You've just lost the prime is all. These pumps are not self priming so don't run the pump without water and burn it up.
 
Yes, I had the seacock closed for that picture. I should have opened it for the picture, lol!
 
We ran the boat from the launch to the dock (15min ride) with the seacock open, but I didn't have the pump running at the time. Should I take it for a spin with the pump running dry and hope it picks up the water? Or should I just do it the hard way and take the hose off and manually prime it?
 
Z-Worthy said:
We ran the boat from the launch to the dock (15min ride) with the seacock open, but I didn't have the pump running at the time. Should I take it for a spin with the pump running dry and hope it picks up the water? Or should I just do it the hard way and take the hose off and manually prime it?
Click to expand...

Both methods work.
 
My old boat never primed for a run after being launched.
This is what I did every year after it went back in the water and it never failed:
While tied at the dock with a/c turned off and the seacock opened (strainer closed of course), I removed the hose from the discharge side of the pump momentarily. As soon as water flowed out of discharge side of pump (almost instantly) I shoved the hose back on and tightened the clamp.
Once the clamp was tightened I turned the a/c on and it worked every time.
 
I run a hose up to the A/C overboard discharge and back fill the system from there. Never fails.
 
wrvond said:
I run a hose up to the A/C overboard discharge and back fill the system from there. Never fails.
Click to expand...

Just a plain old garden hose pushed up against the thru-hull? That's enough pressure to backfill the whole system? I like the ease, but I'm thinking I'll have to resort to JVM's solution after this doesn't work. :grin:

Thanks to everyone! I'm heading down tomorrow to try any and all of these tricks.
 
Take it for a spin and while on plane, turn on the A.C. - this is what I do if I lose prime.

Interested to see how you make out with the hose to through-hull. Please update post after you try it out.

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Reverse priming using the through hull works every time for me.


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I've tried all of the previously mentioned methods on my 280DA and they worked. Something else that worked was doing nothing and let it sit overnite, If everything from inlet seacock, to and including the pump is below the water line it should eventually prime itself.
 
Z-Worthy said:
Just a plain old garden hose pushed up against the thru-hull? That's enough pressure to backfill the whole system? I like the ease, but I'm thinking I'll have to resort to JVM's solution after this doesn't work. :grin:

Thanks to everyone! I'm heading down tomorrow to try any and all of these tricks.
Click to expand...

Leave the unit turned off, hold the hose up to the thru-hull and run the water for a minute or so. Turn the system on and observe the water running out the discharge. If the stream remains steady you were successful, if it stops running you've lost prime again and there's a problem with the system.
Good luck!
 
This will sound wacky. But this worked for me: take a garden house, insert it into the the opening where your unit discharges. Turn on the water and let it be for a few minutes. Remove the hose, turn the unit on and, viola! Not sure where I found this solution, maybe this forum (but I was not a member when I had this issue).
 
I never tried priming with a garden hose through the discharge because my pump was so easy to get to in my 300 Sundancer, but I like that idea.
That's how I winterized the a/c on that boat every year. Once the boat was blocked up out of the water I hand pumped the anti-freeze through the discharge until pure pink came out of the intake.
Not sure why, but I tried priming it several times over the years by just going for a ride with the seacock open and it never worked for me. It wasn't the pump because I had one go bad on me and replaced it and it still wouldn't prime by just going for a ride.
The only reason I can think of was that I had a "South Bay Strainer" on the a/c intake of that boat and that may have had something to do with it.
Anyway, the method I used every season worked every time. If the pump is harder to get to then I like the hose through the discharge idea.
 
Like JVM, my 300 DA doesn't prime from a ride. I usually use the garden hose on the thru hull and back fill it. It's quick and easy and always works.
 
UPDATE:

So the garden hose trick did not work. I don't know if it's just too long of a run on my boat, or if there was too much back pressure, but I had water going EVERYWHERE except into that outlet. I tried it multiple different times, and never got it to work.

It's blowing 25+ and I didn't feel like dealing with all that, so I just took the laborious route and removed the 20yo hose from the outlet on the pump. Apparently this is the first time it's been removed since it left the factory, because it was all sorts of fun. But after managing that, I actually heard the air bubble gurgle up and out. Reinstalled and voila!

Note to self: clean out the strainer BEFORE the boat comes out of the water next year. :smt017
 
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