Exhaust water flow

[Rick.johnson]

Hi Guys
I have a 1987 Hunter 40 legend
With a 4jhe Yanmar engine

Question then I have it running I cant tell if I am getting any good
water flow thru the sea water pump to aid in keeping her cool
for the exhaust water an engine exhaust blows out under the boat waterline

I Am thinking of putting in a small visual flow meter by the Kingston cock or just before the sea water pump inlet in the hose there Now I use a therm laser to take the temp of the engine an she seem always at about 170 deg f

Is there enough flow to use a flow meter

Please Advise Thank Rick

 

[HMT2]

I had one of these on my boat. Super easy to install I loved it! Buy the kit with the alarm.

Cooling Water Flow : AQUALARM, Warning Systems For Land And Sea

AQUALARM : Cooling Water Flow - Security, General Alarm Cooling Water Flow Automatic Sys Monitor Exhaust, Engine Monitors&Sensors Bilge Alarms & Switches Watch Alarm , Aerator, Alarm Mat Fire and Smoke Alarms Audible / Visual Alarms Hose to Barb Adapters Custom Panels Replacement Parts Cellular...

aqualarm.net

 

[Rick.johnson]

Hay Thank Mike that would take care of my problem
To make sure she stays cool

Will get on an give it a try an mount the alarm up in the cock pit area

 

[jssailem]

Lots of options:

• Stick a pole down in the water near the exhaust. Is it being knocked about? Probably you have water flow.
• Put a temp sensor on the exhaust pipe aft of the water injection elbow.
• Use a IR sensor and target the exhaust manifold, then the exhaust hose.
• Get in the dinghy and scoot around to the exhaust port and stick your hand down near the port. You can get a read on temp and pressure.
• Monitor the engine temp. If it is not steady at 170 then you may have a problem.

 

[JoeWhite]

To test the water flow, close the raw water intake thru hull valve, disconnect the hose from the output of the water filter and insert into a 5 gallon bucket of fresh water and see how long it takes for the water to empty when engine is running. Keep a shore water hose handy and fill the bucket before all the water is emptied. I would think it would take about 2 minuites for the bucket to go low. This is best done with 2 people, one at the Helm ready to stop the engine.
If the water temp on the engine is lower than what you are used to, then there may be a clogged intake.
If slow water draw, then check the impeller in raw water pump.
To avoid forgetting to open the raw water intake, I place my engine keys on the valve handle. I have also added a magnet on the handle with a magnetic switch and added a buzzer at the captain's instument display. When key is turned and if the handle is not open the buzzer will sound.

 

[Don S/V ILLusion]

Was the 40 designed to have the engine exhaust below the WL.?

That seems like either a bad design or an overloaded stern. Regardless, since all kinds of bad things can happen unless this is changed, I’d suggest you do that first.

 

[Rick.johnson]

Yes she was designed that way from Hunter

I like the first Answre using the in line electric water flow meter

 

[dlochner]

I had one of these on my boat. Super easy to install I loved it! Buy the kit with the alarm.

Cooling Water Flow : AQUALARM, Warning Systems For Land And Sea

AQUALARM : Cooling Water Flow - Security, General Alarm Cooling Water Flow Automatic Sys Monitor Exhaust, Engine Monitors&Sensors Bilge Alarms & Switches Watch Alarm , Aerator, Alarm Mat Fire and Smoke Alarms Audible / Visual Alarms Hose to Barb Adapters Custom Panels Replacement Parts Cellular...

aqualarm.net

I just learned about this device and will use it on a boat I am refitting.

 

[Ralph Johnstone]

Here's mine in position for a Yanmar 2GM20F :

 

[Ralph Johnstone]

Was the 40 designed to have the engine exhaust below the WL.?

No rhyme Nor reason. Some did, some dinna.

My boat (H-310) and another H-310 came on the same flatbed from the Hunter factory in Fla. Mine has the exhaust below the water line :

The other H-310 had the exhaust roughly in the same location but on the side of the hull and well abover the water line.

The only way you can tell if the engine is running is from the hull vibration. No external sound. Ideal for sneaking up on kayakers.

 

[Tally Ho]

My Hunter 280 also had the exhaust exit below the waterline.

I could hear a difference in the tone of the engine exhaust when I forgot to open the cooling water thru hull.

Would be harder to notice a gradual reduction in cooling water flow though.

Greg

 

[colemj]

If your strainer has a see-through top, you can usually see the water moving in it. Of course, all of these suggestions are one-time checks, and don't tell you if you lose water flow while operating from something like a clog or a broken impeller. The flow meter looks good for that.

Mark

 

[jssailem]

Start your boat. Then step onto the dock and look back in the area of your boats exhaust. When my buddy with his Catalina 36 starts his engine, I can see the exhaust disturbance in the water from the dock.

 

[Rick.johnson]

Well yes there is exhaust coming out from under the aft hull
tell me how to tell if there is cooling water in it from the heat exchanger ?????

 

[dlochner]

Well yes there is exhaust coming out from under the aft hull
tell me how to tell if there is cooling water in it from the heat exchanger ?????

Are you losing coolant? Do you see evidence of leaks on the engine?

 

[Rick.johnson]

Hi Dave
No i am not losing coolant / antifreeze that is in the engine cooling side of the heat exchanger unit
what i can't tell is how much sea water is being pulled up in by the pumped in to the heat exchanger
for after the sea water enter the heat exchanger it flows out an in to the exhaust elbow
then the hot sea water an the engine exhaust exit under the (WL STARBOARD AFT SIDE )
So all i see is the exhaust gases bubbling up in the sea water I can tell if there is hot sea water mixed in with it or not
I hope this clears up the question

 

[dlochner]

That's the question I thought you had, the last comment had me puzzled. If the seawater pump isn't working, the engine will overheat and the hoses and water lift muffler will melt while seawater back fills the boat through the melted hose.

The Aqua Alarm cooling water flow gauge is a good solution. There are other options such as Maretron's Exhaust Temp sensor, and Aqua Alarm's Exhaust system monitors. The Marathon monitors operate over NMEA 2000 network and require a couple of different parts, an alarm module, switch module, and/or a temp module. The Maratron system can get pricey pretty quickly.

 

[jssailem]

Rick... My plumber told me the easiest way to tell if you are getting hot water from the tap is to touch the water coming out of the pipe.

Your boat likely has an exhaust system that looks like this.

The water enters the system at the temperature of the lake/sea/ocean your sitting in. It is injected into the exhaust and runs to the lift muffler. As more exhaust/water is forced in to the muffler the excess is pushed out of the muffler and out the exhaust pipe.
To answer you question how do you know what is being sucked in? It is th volume you see or feel being pushed out.

 

[Rick.johnson]

This is kind of like mine

But mine the exhaust an the exhaust water discharged under the boat about a foot below the water line so i cant tell if there is water mixed in or knot all i see is the gas exhast bulbling up on the aft starboard side
Rick

 

[Leeward Rail]

is to touch the water coming out of the pipe.

Your boat likely has an exhaust system that looks like this.

He specifically said the exhaust exits BELOW the water line.

When my buddy with his Catalina 36 starts his engine, I can see the exhaust disturbance in the water from the dock.

You would see exhaust bubbles even if there was no water flowing through the exhaust.