F44 Cruisair not pumping water

[captainmaniac]

Glad we had a 3 day weekend, otherwise I wouldn't have made it to the boat at all. Too much other crap going on....

Anyways, I managed to get some wiring diagrams for the controls from Dometic, who own(?) Cruisair now. Diagrams don't match up with the controls I have, so may be a different generation (sent them the differences tonight and hoping they can give me better info before end of week). Today was focused more on loading the boat (6 round trips to unload the car), decided I was too beat to rip stuff apart and deferred digging in to AC pump until next weekend. Probably the original factory install of the AC, I have to disassemble a bunch of stuff in the forward starboard hanging locker to get to the back of the AC controls to see what's really going on.

[Big D]

Can you find a picture on line of the pump type you have and post it?

[captainmaniac]

Can you find a picture on line of the pump type you have and post it?

I think it is similar to this (but with black housing):

http://www.marineengineparts.com/coolin ... oning.html

[Big D]

That pump has a magnetically operated impeller that has a habit of being stuck come commissioning time. But if you're sure the pump isn't operating as mentioned in your post, the point is mute. If you remove the screws on the front of the pump housing, you'll see the impeller. It should spin freely in place but first see if the pump is actually running or not. If not, back to the top and determine why. You can see the impeller in this parts breakdown.
http://www.google.ca/url?sa=t&rct=j&q=& ... UDjT6AeS2g

[captainmaniac]

Big D - thanks for the info. Hopefully I can find time this weekend to look closer. Have to help someone move on Saturday. You say the impeller in this pump has a habit of being stuck come commissioning time - first time since 2000 I have ever had a problem with it, so maybe I have just been lucky.

[Big D]

Yes, may have a little growth or hardened sediment, etc. Doesn't take much to prevent it from turning after it's been sitting for 6 months.

[Flyboy]

Probably not your problem, but I sucked a fish up onto my AC thru hull, it sucked some of his meat into the hole and got stuck. Had to remove the hose and blow in it to dislodge the fish. Did not know it was a fish until it floated out from underneath the boat.

[captainmaniac]

Around here, the only fish I am likely to suck up are Carp, and most of them are 30-40 pounds so not likely to get any plugging an intake... And once stuff is turned off, they will just swim away anyways...

Spent the first half of the day today moving furniture from an apartment to a storage unit (pushing 36C / 97F out - think I lost a couple of pounds ), then headed to the boat to try to figure things out. After fighting with fresh water leaks at the hot water tank for a while, gave up before I dug in to the AC raw water pump... (darn replacement PVC fitting at water heater just won't stop leaking... so gotta deal with that tomorrow -- original 90 elbow cracked open and made a heck of a mess shortly after pressurizing system last week).

I tried wacking (lightly) the pump for the AC system with the insulated handle of a wrench to see if that might free a stuck impeller, but no dice. Tomorrow I will attempt to pull the cover and / or housing assembly off of the pump (as per PDF Big D supplied) and see what happens after I spin the impeller manually. May be a disaster as the way this pump has been plumbed... the sea strainer (Sherwood model) for raw water into the pump is piped directly in to the pump cover.... There are no hoses between strainer and pump cover -- just a brass screw fitting between the two, with no discernible fitting for a wench to hold it in position... I fear trying to rotate strainer or pump or anything is just going to lead to unstoppable leaks. So.... think I may have to pull the bowl off of the strainer to gain access to the lower screw holding the pump cover / housing. If I can get access by pulling the bowl, GREAT! If not, I am looking at a much bigger disassembly / reassembly project, with all the worries about leaks that go with that...

I know this is a small potatoes thing -- just a pump... but getting P.O.d about how many levels of the onion I have to peel to just be able to get it dealt with!

[Big D]

Do you have an AC voltage probe pen? These are great at sensing voltage without having to get to a terminal or bare wire. Turn the system on and probe the pump's cable in a few places to see if you get a hit. This will tell you if you're getting voltage there or not. Everybody should have one of these in their tool box. http://content.amprobe.com/images/produ ... _220px.jpg

[captainmaniac]

Well, at least a baby step or two forward... Pump is getting power, and looks like I should be able to pull lower screw if I pull the bowl off the strainer. I liked in my previous post - strainer is not on the intake side, it's on the outlet side... After moving furniture yesterday my body wouldn't bend well enough today for me to get cozy in the bilge to work on the pump, so will try again next weekend.

[captainmaniac]

Spent a bit more time today bending my body in ways it wasn't intended (at least at my age!) to look into pump problems more. Was pleasantly surprised with three things - after removing the bowl from my strainer I could get to the lower screw on the pump cover, how easy the wet side of the pump came apart and went back together (and didn't leak!!!), and that the thru-hull shutoff valve wasn't seized and actually worked!!!

On the down side, wasn't too successful in fixing things...

I know the pump is getting power (used one of these to confirm https://www.homedepot.ca/en/home/p.non- ... 64603.html, but obviously can't confirm voltage received unless I pull connectors apart) and I can hear a hum from the pump (but no vibrations) when it should be pumping. Pump is a 'Marine Development Corporation' (likely March) PMP500, 490 GPH at 3' head.

With the wet side cover off I could spin the impeller easily by hand. Could feel resistance followed by it jumping by itself because of the polarity of the magnets. Nothing physically jamming the impeller, and it was not fused to the shaft. It was a bit dirty / grainy around the magnet at the base of the impeller (with I am guessing metal filings or magnet filings...). Tried to 'wash' that at first before I realized what was going on, then used paper towels to wipe as much magnetic 'grit' off as possible. Not a perfect surface when I was done, but not sure how clean I should make it or scrape it without doing damage to the magnet.

Looked like this when I started - messy, but not a total mess:
NEW

IMG_7986_zpsycdtcnjb.jpg (72.1 KiB) Viewed 3144 times

Cleaned the face of the impeller, cleaned the housing, cleaned out strainer and bowl in case there was a flow issue, also opened seacock to 'flush' incoming line and water flowed freely and clean.

After putting pump back together and opening seacock, when we turn on AC I can again can hear pump humming, but no water flowing through AC. Also noticed a new symptom today -- after about 10-15 seconds of controls set to AC and pump humming, AC breaker (15A) popped. Had it running longer than that last weekend (up to 30 seconds) without breaker popping.

One test I realize I neglected to do was to try to run the pump with cover partly separated from the housing to see if I could visually see the impeller spinning, but since the shaft would not have been seated properly at both ends don't know if that would have been a misleading test anyways??

So, at at this point I am guessing the pump motor itself is fried or shorting out (only supposed to draw 2 amps) and I need to replace the whole unit. If it is popping a breaker, it sounds electrical.

Any thoughts / experiences / suggestions are appreciated!

[Big D]

With someone at the controls and you at the pump, have them turn the unit on while you quickly loosen off the face of the pump slightly while the pump is running. Loosen it enough and it should start squirting out at pressure if the pump is working. This is often required to get the pump going first time in the Spring or after it looses it's prime from coming out of the water for one reason or another.

Sometimes with no raw water, it doesn't take long before the system shuts down or pops a breaker. Do the above quickly before the system freezes up. If it does, it won't let water through so you need to walk away for a while then start over.

Make sure you're not sucking air from the strainer, connections, etc.

I assume this is all below the waterline?

[mikeandanne]

maybe I can add something now that you know the motor is turning.....couple of times we have had to prime our pump by removing the hose from the thru hull , hold up above the pump level and pour water in the hose to the inlet side of pump thru funnel or whatever you have...turn on pump and keep pouring, has worked for us..hope it works out for ya...if you just have the controls on the first click, then the compressor should not start, only water side and fans I believe.

[captainmaniac]

Yes, pump is below the waterline. With the bowl off the strainer I get a good healthy flow of water with the seacock open. I will try the additional suggestions next chance I get.

[mikeandanne]

One more, try disconnecting the pump discharge hose and put your shop vac on that and feel for suction at the discharge where it exits the hull just to make sure the discharge hoses are clear, never know what crawled in there over the winter.If it it the same as ours its a straight shot thru , no valves.