Mainship 390 Questions

Good Evening,
I have a few questions about my Mainship 390 (2001).

1. The boat has a pump mounted just outside the rear door under the hatch. It pulls water from a seacock that's just beside the seacock that provides cooling water for the generator. The other end of this pump is connected to translucent water pipe. I thought it might go to the head or the HVAC but it doesn't. I can't figure out what it's for.

2. I have a fresh water leak at the fittings to the transom shower pump. Is there a way to get into that area or a trick to repair it? It's a big drip ever second and it winds up in the bilge beneath the engine. The fresh water pumps turns on for a second about every 5 minutes. Maybe pull the port side fresh water tank?

3. Where are the pumps that turn on when the front or rear HVAC is energized? The units I have are Marine Air. The boat has a separate circuit breaker for an AC Pump but it only comes on when the unit turns on and starts to cool.

4. Has anyone pulled and repaired the main engine heat exchanger? I have the CAT 3126 and I loose a little coolant every 10 hours or so. It's no in the oil (thank goodness) so i assume it's passing into the heat exchanger.

5. One of the 120 VAC breakers (port side) on the main panel is label accessory. It's the last one at the bottom of the panel. Anyone know what it powers or how to figure that out? Seems like MS should have labeled it.

I get aggravated with all the systems and the little issues and then we take it out for a little cruise and I happy to have it.

Thanks to anyone who can help me with these.

Hawk

Usually breakers labeled accessory are for expansion. Doe it have a wire on it?

I understand the frustration of a "new" boat without good documentation. I find as a general rule Mainship did a poor job of documenting the boats for owners.
Some models are better than others. Do you have any MS owners manual?
My MS 34HT is fairly open all throughout the bilge so easy to trace lines & systems and MS did label most through hulls. If they didn't on the 390 I'd suggest a label be added to all that you trace & figure out... memory is a terrible thing to lose!

#1 The only other through hull that I can think of that has a pump would be a raw water wash down. Do you have one... likely at the bow?
I would have guessed AC with clear section to easily visually check for flow, but you already ruled that out.

#2 Are you talking about the outdoor shower in the cockpit area? At least on my 34 that shower doesn't have a separate pump. It just runs off the fresh water pump hot & cold. I have had a leak behind it that ended up in the bilge. If thats it the whole unit comes out the front w 4 screws and you can get at the fittings on the back side.

#3 AC pump... it will be near a thru hull (duh obviously) and mounted low... below the waterline as they usually wont self prime. They are quiet so difficult to find via sound. Mine is far aft almost to the transom and has a "T" immediately after the pump discharge to split the flow to saloon & fwd cabin units.
No real answers but hope the hints help!
Welcome to the MS world.
I found the electrical systems the hardest to trace but have found and or modified many of them over the years. There are a fair number of 390s out there so shouldn't be too hard to find someone with more history & knowledge of the systems.

I haven't opened the panel but I will. Seems odd that an expansion spot would have a breaker installed but that may well be the case.

I bet that pump is indeed for the anchor wash down. I'll look the next time I'm there.

Thank you!

Hawk

Hawkshaw1 said:

Good Evening,
I have a few questions about my Mainship 390 (2001).

1. The boat has a pump mounted just outside the rear door under the hatch. It pulls water from a seacock that's just beside the seacock that provides cooling water for the generator. The other end of this pump is connected to translucent water pipe. I thought it might go to the head or the HVAC but it doesn't. I can't figure out what it's for.

2. I have a fresh water leak at the fittings to the transom shower pump. Is there a way to get into that area or a trick to repair it? It's a big drip ever second and it winds up in the bilge beneath the engine. The fresh water pumps turns on for a second about every 5 minutes. Maybe pull the port side fresh water tank?

3. Where are the pumps that turn on when the front or rear HVAC is energized? The units I have are Marine Air. The boat has a separate circuit breaker for an AC Pump but it only comes on when the unit turns on and starts to cool.

4. Has anyone pulled and repaired the main engine heat exchanger? I have the CAT 3126 and I loose a little coolant every 10 hours or so. It's no in the oil (thank goodness) so i assume it's passing into the heat exchanger.

5. One of the 120 VAC breakers (port side) on the main panel is label accessory. It's the last one at the bottom of the panel. Anyone know what it powers or how to figure that out? Seems like MS should have labeled it.

I get aggravated with all the systems and the little issues and then we take it out for a little cruise and I happy to have it.

Thanks to anyone who can help me with these.

Hawk

Click to expand...

The AC Pump is on the bulkhead on the starboard side of the engine compartment right above the trough hull,(as Don Mentioned) it then delivers to the forward and Main salon AC Units. IT DOES NOT SELF PRIME. and should only come on when the Unit is heating or cooling.
The fan defaults to run all the time although is a setting that can be changed.
(if you need manuals let me know and I will send you the complete manuals for the 390, including wiring and plumbing schematics.
Pump in Lazarette behind Patio door is an add on, the only wash down is from the Fresh Water Tank (Boat was built in salt water) a PO has added, Might do that myself, to relive the Fresh water tank as we are on the great lakes, and drives me crazy using fresh water to clean the anchor. Accessory on Panel is indeed for expansion.
Cooling leaking not sure I would contact a mechanic over my pay grade. I had it leaking from the Hose clamp on the overflow. and easy fix.

Cartouche said:

The AC Pump is on the bulkhead on the starboard side of the engine compartment right above the trough hull,(as Don Mentioned) it then delivers to the forward and Main salon AC Units. IT DOES NOT SELF PRIME. and should only come on when the Unit is heating or cooling.
The fan defaults to run all the time although is a setting that can be changed.
(if you need manuals let me know and I will send you the complete manuals for the 390, including wiring and plumbing schematics.
Pump in Lazarette behind Patio door is an add on, the only wash down is from the Fresh Water Tank (Boat was built in salt water) a PO has added, Might do that myself, to relive the Fresh water tank as we are on the great lakes, and drives me crazy using fresh water to clean the anchor. Accessory on Panel is indeed for expansion.
Cooling leaking not sure I would contact a mechanic over my pay grade. I had it leaking from the Hose clamp on the overflow. and easy fix.

Click to expand...

Spent some time on the boat today. The coolant leak was coming from a coolant hose leak at the clamp. We tightened the clamp and the leak disappeared. The hoses are almost 20 years old and are the originals painted white. I plan to change them all to silicone in the next month or so.

Looks like the heat exchanger is good.

Confirmed the HVAC pump is indeed, just as you stated, mounted in the engine room on the starboard side.
The fresh water pump is mounted in the engine room on the port side. It runs when the transom shower and the anchor washdown are used.

Thanks for the offer on the AC control. I found it in the stack of documents that came with the boat.

I still have no idea what the seawater pump mounted in the lazarette is used for. It doesn't look like it was added later because the the hose and seacock look identical to the seacock and hose to the genset. I'll keep looking.

Thanks for all the help!

Hawk

The seawater pump in the rear lazarette is for the salt water washdown in the aft side of the coackpit. There is a water faucet next to the dockside water inlet. When you open the faucet, it makes the pump go in. As far as the leak in the shower, well, you have to have a skinny guy lay on his back and slide under the aft cockpit cover. Uou can then remove or replace the fitting and hose.

Thanks Skipper, you're right!

The extra pump in the Lazzarette supplies sea water to a washdown spigot. I also labeled the breaker.

Hawk

Looks like you have answers to everything but question 2.
To fix it you need a really skinny guy to lay on top of the port side water tank.
In the meantime if you open the hatch directly below the lower helm station you will see a potable water manifold with shut offs for all individual systems. Shut off the one for the aft shower. At least it will stop the leak until you find a skinny friend.
John

Hawkshaw1 said:

Spent some time on the boat today. The coolant leak was coming from a coolant hose leak at the clamp. We tightened the clamp and the leak disappeared. The hoses are almost 20 years old and are the originals painted white. I plan to change them all to silicone in the next month or so.

Looks like the heat exchanger is good.

Confirmed the HVAC pump is indeed, just as you stated, mounted in the engine room on the starboard side.
The fresh water pump is mounted in the engine room on the port side. It runs when the transom shower and the anchor washdown are used.

Thanks for the offer on the AC control. I found it in the stack of documents that came with the boat.

I still have no idea what the seawater pump mounted in the lazarette is used for. It doesn't look like it was added later because the the hose and seacock look identical to the seacock and hose to the genset. I'll keep looking.

Thanks for all the help!

Hawk

Click to expand...

are you sure its not for the generator should be a Bronze Trainer between through hull and generator

Cartouche said:

are you sure its not for the generator should be a Bronze Trainer between through hull and generator

Click to expand...

I am sure. There is a seacock right beside the one to the pump that goes directly to the impeller on the generator. I am going to label all these soon. Of course after you label them you remember it.

Hawk.