Naiad stabilizers overheating

[BCRyan]

Hi all - I'm getting stumped by an issue that has recently cropped up and hoping someone might have some experience in this area.

My 2001 Horizon MY has Naiad stabilizers, model 254, likely original from the boat's build. During a recent trip from San Francisco to Newport, Oregon, the high temp light started coming on, so we turned the system off (thankfully it wasn't needed at that point). In Newport, I found that the sea strainer was at least half full of seaweed, and figured I had it solved as I emptied that and put everything back together.

Unfortunately, the overheating issue continues -- about 45 minutes after running the system either in "Centered" or "On", the high temp light comes on, even when the system is not working hard at all. Also concerning is that the seawater flow from the outlet (just above waterline) seems to be pretty low. I'm not 100%, but it seems like it used to be much more.

The pump (pic below) looks to be fairly new.

I've done the following to troubleshoot:

1) Bypass the Naiad heat exchanger, i.e. thru-hull -> sea strainer -> pump -> inlet hose connected directly to the outlet hose -> outlet. The flow is roaring and *significantly* greater than normal in this mode.

2) Connect the outlet of the heat exchanger to a garden hose and back-flush the HE into a bucket. Flow seems to be pretty strong and no debris came out, but this is also under tap water pressure (~60 psi??)

3) Open up the impeller chamber on the pump (everything perfectly clean).

4) Double-check the sea strainer (still clean)

Since the flow with everything connected normally is so much less than case 1) above, I'm inclined to suspect that something in the HE piping is restricting flow. If this needs to be cleaned, does anyone know how this gets accomplished? I have the manual but it shows nothing more than a system diagram and definitely nothing about cleaning of the HE.

Some pics below. If anyone has any suggestions, I'm all ears.

Thank you!

 

[HTurner]

Sometimes, even after cleaning the strainer, there is debris before the strainer -- hose and thruhull. The thruhull may be partially stopped up. Check these, especially if water flow seems low.

 

[BCRyan]

Sometimes, even after cleaning the strainer, there is debris before the strainer -- hose and thruhull. The thruhull may be partially stopped up. Check these, especially if water flow seems low.

Thank you for the reply. The situation you suggest is what I attempted to verify in step 1) above. In that case, the flow with everything in the system (but the HE itself) is very, very strong.

 

[HTurner]

You may want to try a Barnacle Buster clean out of the HE, just like one would do with a Marine Air Conditioner.

 

[BCRyan]

You may want to try a Barnacle Buster clean out of the HE, just like one would do with a Marine Air Conditioner.

This sounds like a good next step, thanks!

 

[Mac2]

I don't mean to insult, but how is the oil level, and what is your temperature at the oil/temp gauge? I have the same system and had a small oil leak at the fill cap, which I solved with some Gasoila thread sealant.

 

[BCRyan]

I don't mean to insult, but how is the oil level, and what is your temperature at the oil/temp gauge? I have the same system and had a small oil leak at the fill cap, which I solved with some Gasoila thread sealant.

No insult whatsoever. Oil level is about a 1/2" below the "full" line when cold. Temperature (using the little built-in thermometer gauge) appears to be 150 when operating. I believe that Naiad wants to see the temperature maintained below 140.

 

[Mac2]

One other thing to consider. There is a oil filter. Mine has a weird pointer on a colored graph (I think it's like a traffic light-green, yellow, red). If that is restricting oil flow, it could be the problem. It was passed on to me to never replace the filter unless I absolutely have to. Not sure why (a naiad tech passed it on to a friend). I was going to replace it just because of the age, but will wait till it gets in the yellow.

 

[magna 6882]

I am not familiar with niad but do understand hydraulics.Heat gets generated mostly from pressure and the high pressures seen when running thru valves. I would be also looking at what the pressure valves are seeing. I know on my keypower system it runs about 1000 psi. If i turn it off even though fluid is still running through the loop it generates very little heat. The valve was factory set at 1200 but i lowered it to reduce operating temps. As far as heat most AW fluids have a high temp of 200 with a working high temp of 180. My system is pto engine driven so the fluid is running whenever the engine is. If this is the case with you you should be seeing marginal heat when running at low pressures.If you see heat buildup then filters,screens or even possibly the fluid itself would be suspect. Again no experience with niad design so my thoughts may have no value.

 

[boatnbump]

The tube that goes in the oil tank for the water is very small. I would make sure it is not plugged. Also the hose going from the oil tank to the discharge is nothing special it can be kinked or if it overheated it may be deteriorated where it connects to the oil tank.. Its a simple cooling system it should be easy to go through.

 

[Insequent]

I agree with comment above - barnacle buster de-scale of HX tubes is a good next step, particularly as it seems nothing else in the system has changed.

On my 252's (2012 install) I have a valve on the cooling water line to control flow rate. Perhaps look to see if you also have one - perhaps someone working in the ER bumped that valve closed a bit?

 

[BCRyan]

One other thing to consider. There is a oil filter. Mine has a weird pointer on a colored graph (I think it's like a traffic light-green, yellow, red). If that is restricting oil flow, it could be the problem. It was passed on to me to never replace the filter unless I absolutely have to. Not sure why (a naiad tech passed it on to a friend). I was going to replace it just because of the age, but will wait till it gets in the yellow.

I have the same thing. I know that it's in the green when everything is off but I'll double-check it when running.

 

[BCRyan]

I am not familiar with niad but do understand hydraulics.Heat gets generated mostly from pressure and the high pressures seen when running thru valves. I would be also looking at what the pressure valves are seeing. I know on my keypower system it runs about 1000 psi. If i turn it off even though fluid is still running through the loop it generates very little heat. The valve was factory set at 1200 but i lowered it to reduce operating temps. As far as heat most AW fluids have a high temp of 200 with a working high temp of 180. My system is pto engine driven so the fluid is running whenever the engine is. If this is the case with you you should be seeing marginal heat when running at low pressures.If you see heat buildup then filters,screens or even possibly the fluid itself would be suspect. Again no experience with niad design so my thoughts may have no value.

Good comments, thanks. I'll look at pressures while operating and see where they are compared to recommended settings.

I should add that we used the stabilizers for 2 days in "on" (active) mode while off the Washington coast (taking swells from the port beam) and they worked fine, thankfully. When turned off, the temp light would go off after a few minutes, so it seems like we're just barely on the edge of overheating.
Increased flow through the HE should take care of things, and I just need to wait until we're in a port where I can pick up some barnacle buster.

 

[FlyFast-Boat Slow]

No insult whatsoever. Oil level is about a 1/2" below the "full" line when cold. Temperature (using the little built-in thermometer gauge) appears to be 150 when operating. I believe that Naiad wants to see the temperature maintained below 140.

I've had over-temp problems in the past with my NAIAD 252s that were due to a poor cooling water design using bleed water from the main engine wet exhaust that I later fixed with a standalone pump just for the NAIADs.

Your situation sounds different though. Maybe the 254s have a lower temperature tolerance but on the 252s the over-temp is about 175F (IIRC). If your reservoir is only 150F I would think you are "in the green." Do you have an IR temp gun you can use to check the tank temp with? [Note - Using a Sharpie I put a crosshairs on the tank with the expected temperature so anyone could do an ER check and know if something was out of range.]

Before getting too wound up in fixing the cooling system I would verify that the problem is not something uber-simple like a bad ground on the temperature sensor circuit.

Lastly, your NAIAD manual should give you recommended cooling water flow rates that can be checked with a bucket and stop watch at the through-hull.

 

[beachbum5953]

Naiad problems

Hi,
I've got a 252 system which is probably 10 years old was installed in 2013. I had a situation with mine that has continued for eight years, but is more of a PITA than a "problem".
In 2014, we were broached going around Point Reyes in CA and rolled over so far that fluid came out of the cap. I immediate had all kinds of alarms, including the high temp alarm.
For the rest of our trip to Baltimore, we had multiple problems that was never solved until we were in CT and had the Naiad service department redo part of the install.
Couple of things that I learned, which may only be applicable to the 252, as I was paying for my education from Naiad service...

Cooling water only needs to be approximately 5 gallons per minute, which doesn't look like too much compared to the A/C cooling discharge.
Fluid level should only be about 1/2 filled on the gauge when cool.
Leaks are VERY difficult to find and generally Chinese hydraulic fittings will leak at high temps.
The only time you need to worry about the high temp alarm is when it is at or above 200 degrees F.

After all of the work on the system by Naiad, I STILL got a high temp alarm. Naiad then replaced the sensor and everything else associated with the high temp alarm... AND... Guess what... I still got a High Temp alarm. Naiad threw up their hands and said I'd have to live with it.

I agree that a cooling water flush of the system would be a good idea. In addition, I keep a chlorine tablet in my strainer to keep barnacles from growing the in the summer.

I still have a problem with getting air locks in my cooling water system while underway, but I suspect that's because the intake fitting is right behind my fins and my best guess is that the movement of the fins generate bubbles which accumulate and eventually cause the airlock... the is a total SWAG though, and I chalk it up to part of the boat's "personality"!

Good luck...

 

[DW1979OA]

I have an ABTrac system on my boat. There is a speed control knob for adjusting the hydraulic motor that turns the impeller for the cooling raw water. My knob gets “bumped” when I’m servicing the mains raw water strainers and it doesn’t take much to reduce flow. That is my first place to check if overheating

 

[BCRyan]

I've had over-temp problems in the past with my NAIAD 252s that were due to a poor cooling water design using bleed water from the main engine wet exhaust that I later fixed with a standalone pump just for the NAIADs.

Your situation sounds different though. Maybe the 254s have a lower temperature tolerance but on the 252s the over-temp is about 175F (IIRC). If your reservoir is only 150F I would think you are "in the green." Do you have an IR temp gun you can use to check the tank temp with? [Note - Using a Sharpie I put a crosshairs on the tank with the expected temperature so anyone could do an ER check and know if something was out of range.]

Before getting too wound up in fixing the cooling system I would verify that the problem is not something uber-simple like a bad ground on the temperature sensor circuit.

Lastly, your NAIAD manual should give you recommended cooling water flow rates that can be checked with a bucket and stop watch at the through-hull.

Really great information, thank you!! Yes, I have a separate and dedicated cooling pump for the stabilizers. I do have an IR gun and will be checking that -- good idea.

 

[BCRyan]

Hi,
I've got a 252 system which is probably 10 years old was installed in 2013. I had a situation with mine that has continued for eight years, but is more of a PITA than a "problem".
In 2014, we were broached going around Point Reyes in CA and rolled over so far that fluid came out of the cap. I immediate had all kinds of alarms, including the high temp alarm.
For the rest of our trip to Baltimore, we had multiple problems that was never solved until we were in CT and had the Naiad service department redo part of the install.
Couple of things that I learned, which may only be applicable to the 252, as I was paying for my education from Naiad service...

Cooling water only needs to be approximately 5 gallons per minute, which doesn't look like too much compared to the A/C cooling discharge.
Fluid level should only be about 1/2 filled on the gauge when cool.
Leaks are VERY difficult to find and generally Chinese hydraulic fittings will leak at high temps.
The only time you need to worry about the high temp alarm is when it is at or above 200 degrees F.

After all of the work on the system by Naiad, I STILL got a high temp alarm. Naiad then replaced the sensor and everything else associated with the high temp alarm... AND... Guess what... I still got a High Temp alarm. Naiad threw up their hands and said I'd have to live with it.

I agree that a cooling water flush of the system would be a good idea. In addition, I keep a chlorine tablet in my strainer to keep barnacles from growing the in the summer.

I still have a problem with getting air locks in my cooling water system while underway, but I suspect that's because the intake fitting is right behind my fins and my best guess is that the movement of the fins generate bubbles which accumulate and eventually cause the airlock... the is a total SWAG though, and I chalk it up to part of the boat's "personality"!

Good luck...

Wow, this is incredibly useful and relevant information. I've yet to find some barnacle buster (currently cruising in the BC Gulf Islands) but fully intend to do that once I can. Thank you!

 

[BCRyan]

I have an ABTrac system on my boat. There is a speed control knob for adjusting the hydraulic motor that turns the impeller for the cooling raw water. My knob gets “bumped” when I’m servicing the mains raw water strainers and it doesn’t take much to reduce flow. That is my first place to check if overheating

Thanks, but my 120VAC pump (Naiad labeled) doesn't appear to have any sort of speed adjustment. Great suggestion, but unfortunately I don't think this is my issue...

 

[Mac2]

beachbum: The chlorine tablet seems like a great idea. Do you do this with all the strainers? Also, you only do this in summer. Why? I'm guessing water temps if your inland of the pacific.

 

[JP2]

Does the description indicate possible AIR in the cooling system?

 

[beachbum5953]

chlorine tablets

Hi,
I spend most of my time in the Inner Harbor of Baltimore with salty brackish wate and it's only seriously hot when I'm usually in northern waters with slightly cooler water. n

That said, I always use a chlorine tab in the A/C/heater system, 24/7/12. In the summer I use a tab in the stabilizer strainer, and all strainers, and put one in the strainer when I settle in for the winter.

When I'm in fertile, hot water, like Savannah or the SE USA waters, I usually run tabs in all of my raw water strainers. Barnacles love moving water, so they thrive in water flowing over them constantly. A former USN diver who cleaned my bottom and running gear in Savannah told me that if I didn't want barnacles to grow on the running gear, I should always run the props at higher RPM at least every two weeks when in the Savannah river because it was so fertile.

BTW, two types of chlorine tablets are available... normal 1" diameter and a 3" diameter. I use the big on when I'm in the SE or hot water. Small in the mid-Atlantic and norther waters.

 

[BCRyan]

Does the description indicate possible AIR in the cooling system?

Possibly, but it's not apparent to me to be the issue.

For example, with much of the raw water purged from the system and air both before and after the pump, the pump will prime itself within about 5 seconds and air appears to be quickly pushed through and out of the system. There's a sight bowl at the top of the power unit (with one green and two white balls inside) that will hold some air, but even that little pocket of air will disappear within about 15 minutes of running.

Also, there's a bleed port on the top of the pump's impeller chamber and I've cracked that to see if any air is impeding the full operation of the impeller, but nothing but water ever comes out of that.

 

[BCRyan]

Maybe the 254s have a lower temperature tolerance but on the 252s the over-temp is about 175F (IIRC). If your reservoir is only 150F I would think you are "in the green." Do you have an IR temp gun you can use to check the tank temp with?

My IR gun reads 159 degrees on the outside of the oil reservoir after running for an hour or so. I also went back into the manual and it states that the system temperature should never exceed 170 degrees. With this, I'm now feeling better about the situation and wondering if my "high temp" switch is maybe in need of replacing.

I'm still looking for some Barnacle Buster (or phosphoric acid) for the heat exchanger, as I doubt that this 20 year-old system has ever been flushed/cleaned, so it certainly can't hurt.

Thanks again to everyone and the great info / suggestions!