Outboard An outboard motor is a propulsion system for boats, consisting of a self-contained unit that includes engine, gearbox and propeller or jet drive, designed to be affixed to the outside of the transom. They are the most common motorized method of propelling small watercraft. As well a…Outboard motor
How does an outboard cool the water?
The real job of cooling the outboard comes when the water goes down these other holes here, because they lead to the water jackets around the Pistons. So I'll show you, I'll sort of shine the light and show you how that works. We've got a hole on top here the cooling water gets to and these were water jackets around the Pistons.
How does an outboard motor work?
With only a very few exceptions (such as Honda’s 2.3hp model) outboard engines are water-cooled. An impeller pump at the bottom of the leg above the gearbox pumps water up to the motor, which then travels back down the leg and exits under water.
What are the most common outboard engine cooling system problems?
Generally outboard engine cooling system problems stem from a lack of basic maintenance – the impeller should be changed annually and engines used in salt water should be regularly flushed through with fresh water to ensure corrosion and scaling is kept to a minimum.
Why won’t my Boat’s cooling system work?
If clearing the nozzle doesn’t improve the flow, that indicates either restricted cooling system flow or a weak water pump. The water intake for your engine’s cooling system is located forward of the propeller on the lower unit housing. Look for some cast-in grating or perhaps a screwed-in plastic screen.
Where does cooling water come out of an outboard?
10:2514:02Outboard cooling water - YouTubeYouTubeStart of suggested clipEnd of suggested clipWe can see that light coming out to places inside the casing. And then down here that goes insideMoreWe can see that light coming out to places inside the casing. And then down here that goes inside this exhaust manifold. And this is where the exhaust comes out here.
How does a water cooled outboard work?
1:393:52Outboard Water Cooling System Overview - YouTubeYouTubeStart of suggested clipEnd of suggested clipOkay that's right here okay that's the cooling water going into the cylinder head it completelyMoreOkay that's right here okay that's the cooling water going into the cylinder head it completely fills this area around the cylinder becomes hot with the heat of the motor and the exhaust.
How does a boat motor cooling system work?
The raw water is pumped through a bundle of small tubes in a chamber filled with the hot engine coolant. The tubes are cooled by the colder raw water the allowing the tubes to absorb the heat of the engine coolant. To function correctly, a heat exchanger must be carefully matched to your boat's engine.
How does a thermostat work in an outboard motor?
A thermostat is designed to hold the cooling water in the block until it reaches the temperature set by the engine manufacturer. Generally, this is between 50 and 60 degrees Celsius. It then opens to release the water before it gets too hot and overheats the outboard.
How does a Yamaha outboard cooling system work?
Your water pump is responsible for keeping your engine cool. It's a simple system that works very well. Cooling water is drawn in through the intake grates on your lower unit, up to and through a rubber impeller keyed to the drive shaft on top of the lower unit. It's then pumped up into the powerhead of your outboard.
Which is better air cooled or water cooled boat motor?
Water cooling protects the engine from temp extremes better, allowing tighter tolerances and smoother operation and prolonging component life. Air cooled engines have be made to allow for greater expansion due to heat, so they never are as smooth.
What keeps a boat engine cool?
Most marine inboard engines are fresh water cooled. Much like your car, a captive amount of freshwater (coolant) is continually circulated through a heat exchanger that maintains the engine at a temperature set by the thermostat.
How much water should be coming out of outboard?
Usually the cooling water pisses out of a small hole under the power head. There should be a hols approx 3 mm diameter facing down and a bit out. Normally a continuous flow expected, unless mercs are totally different.
Do you need a thermostat in an outboard motor?
Can I Run My Outboard Without The Thermostat? Yes, you can temporarily run your outboard without the thermostat and not harm the engine. No, you can not remove the thermostat and continue running the engine for long periods of time without causing harm to the engine.
How do I know if my outboard thermostat is working?
Step 2: Put the thermostat in a bowl and immerse it in boiling water. As the thermostat heats up, it should open. When you remove it from the boiling water, allow it to cool and it should close again. If the thermostat remains open or closed, it has failed and must be replaced.
How do you know if thermostat is bad outboard?
Symptoms of a Bad ThermostatEngine overheating, particularly at idle and low running speed.Engine going into limited power or slow mode to mitigate against overheating.Increased fuel consumption.
What temp should an outboard run at?
140 or so (at the stat). The thing you need to remember is most boat water temp gauges are not precision instruments. 2 Strokes run a little hotter. That's hot, but might not be accurate.
How does a keel cooled engine work?
A keel cooler is a closed circuit cooling system mounted externally on the vessel's hull below the waterline. The concept of keel cooling is similar to the application of a radiator on a car. Engine coolant is circulated through the keel cooler, which transfers heat from the coolant before it returns to the engine.
Do you need a thermostat in an outboard motor?
Can I Run My Outboard Without The Thermostat? Yes, you can temporarily run your outboard without the thermostat and not harm the engine. No, you can not remove the thermostat and continue running the engine for long periods of time without causing harm to the engine.
Should water come out of exhaust on outboard?
It's normal for cooling water to also exit through the exhaust. It's part of the cooling system (in addition to the pee stream). And when you aren't moving, the exhaust might bubble out from the lower unit because it also exits out through the prop while underway.
How does a marine oil cooler work?
the hot oil coming inside and going away in vertical manner. the water is passing inside the tubes in horizontal manner. then the hot oil(which is coming from the engine)passing inside the cooler, water is cooled the oil which carried by the aluminium tubes.
What does the squirter on an outboard engine mean?
It is the best indicator that the cooling system on your engine is functioning as it should. This is especially important on smaller engine installations that may not be equipped with a temperature gauge for monitoring such things. The relative velocity and volume of water that comes squirting from this small nozzle is quite telling to the trained eye.
Where is the water intake located on a propeller?
The water intake for your engine’s cooling system is located forward of the prop eller on the lower unit housing.
Why is my outboard engine not cooling?
Generally outboard engine cooling system problems stem from a lack of basic maintenance – the impeller should be changed annually and engines used in salt water should be regularly flushed through with fresh water to ensure corrosion and scaling is kept to a minimum. Problems tend to stem from these two sources – failure of the impeller, or a partial blockage of the waterways by salt and calcium deposits.
Where do you put the cooling pipe on a lower gearbox?
When refitting the lower unit, the drive shaft may need a little bit of manoeuvring to get it into the correct position, and the cooling pipe leading upwards toward the powerhead must be fitted into the rubber connector on top of the bottom unit. Finally, don't forget to smear a little barium chromate paste on the bolts before refitting the gearbox.
Where is the impeller on a water pump?
The impeller is located on the top of the gearbox – remove the bolts that secure the water pump in place and slide it up the drive shaft. Any missing bits of impeller blade need to be recovered before reassembling the pump, as they will obstruct the already narrow waterways. Left: Unbolting the lower unit.
Is an outboard engine water cooled?
Outboard engines are great - if you look after them. With only a very few exceptions (such as Honda’s 2.3hp model) outboard engines are water-cooled. An impeller pump at the bottom of the leg above the gearbox pumps water up to the motor, which then travels back down the leg and exits under water. A tell tale hole under the motor itself or in ...
What does a tell tale hole in a motor mean?
A tell tale hole under the motor itself or in the leg shows whether water is flowing as it should. Often the only sign of a problem is when the water from this tell tale stops flowing – it’s important to monitor it all the time the engine is in use, even though it’s not normally in your line of sight.
When will the outboard engine start in 2021?
June 7, 2021. Outboard engine troubleshooting is a handy skill. While a fuel system problem may make it impossible to start an the engine, outboard cooling system problems have the potential to destroy an otherwise healthy motor as overheating can lead to a blown cylinder head gasket, or even a complete seizure of the engine.
Can you fix an outboard boat at sea?
Larger outboards may be impossible to fix at sea, but generally have a limp home mode in which the motor will run at a slow speed that reduces the chances of long-term damage being inflicted through overheating. Smaller engines used as auxiliary power for a dayboat or small yacht can often be lifted onboard for repair, assuming the boat carries appropriate tools and spares.
What happens when an outboard motor starts?
When this happens the outboard is sending drive to the boat and moving it forward. The force of this transfer is absorbed by the water around the boat and the transom, which houses the outboard engine.
What outboard engines do outboard clinics work on?
Most outboards need a solution to help prevent this damage, and that mixture is usually added to the fuel and then run through the machine. If your having problems with your outboard engine your in luck Outboard Clinic works on all major lines such as Suzuki , Yamaha , Mercury , Polaris , Honda , Johnson , Evinrude , seadoo.
Why do outboard boats have bubbles?
Since they do not have radiators , this is a necessary part of their design and operation. Most all of the exhaust of an outboard is expelled through the bottom fin of the propeller. This is why there are bubbles coming up from the propellers when the boat is started.
How many strokes does an outboard boat engine take?
They run in either a two-stroke (like most lawnmower engines) or four-stroke process. This means that the engine takes two or four “strokes” to complete the cycle.
What are the stages of ignition in a two stroke engine?
In two-stroke engines, the downward cycle and upward cycle of the piston complete all four stages of ignition in the engine: it will intake gas and air, compress it, fire a spark and ignite, and then exhaust the fumes.
What is an outboard water cooling system?
An outboard water cooling system is a once through “heat exchanger”. That is, it exchanges excessive heat from the engine to a place where it is unobjectionable.
Why is my outboard motor not cooling?
However, there are two reasons why an outboard motor is not cooled properly. Generally, they are insufficient cooling water flow (several reasons) or fouled heat exchanger surfaces one reason).
What happens when the temperature of the thermostat is above the opening temperature point?
If temperature rises above “opening temperature point”, water will pass through the cooling passages of the heads and block. Heat will be transferred between the surfaces within the heads/block and the once through cooling water. The heated cooling water will be expelled through the lower unit. Once enough heat is removed, and drops the temperature of the cooling water below the “closing temperature point” of the thermostat valve (s), the thermostat valve (s) will close again.
What happens if the thermostat is closed?
If I read this correctly, if the thermostat is closed no water is flowing through either the "In-bank exhaust" or the block. That is flow is stopped at the thermostat , yet flow is not interrupted through the "Exhaust pipe" (it continues). Water constantly flows through/over (not sure if which/both?) the oil pan and the exhaust pipe.
How does water flow through an outboard?
Water is drawn through the water pump from the lower unit to the cooling passages in the heads and block to the “thermostat valves”. If the valves are closed due to being below “opening temperature point” water will not pass through the heads and block and by-passed through the lower unit and exhausted (some outboards use pressure control valves to prevent excessive pressures).
Is a closed switch on or off?
And then there are engine makers that refer to a closed switch as be "on" and an open switch as being "off".
Do muffler tubes melt?
and yes I have seen muffler tubes melt into slag particles.
What causes a boat motor to overheat?
Overheating can and does cause premature failure due to swelling ...
What is enclosed cooling system?
Figure 2 shows the typical "enclosed" cooling system. This configuration utilizes contained antifreeze in the main part of the motor and also uses a heat exchanger much like the purpose of a radiator in an automotive application. The difference being instead of relying on air flow to cool the antifreeze, fresh seawater is pumped through the heat exchanger and then exits the boat through the exhaust.
Why does my thermostat overheat?
Finally, the third most common reason of an overheat problem with the cooling system can be attributed to clogged water passages, usually in the exhaust manifolds. Since most exhaust manifolds are made of cast iron, rust and corrosion are always present.
How is fresh water drawn from a boat?
Fresh seawater is normally drawn by a belt driven pump from a thru hull fitting in hull of boat on inboards, or by water pump in stern drive through the lower unit water passages on an inboard/outboard, and then exits the boat through the exhaust. ^Click to enlarge^.
Why does my impeller go bad?
An impeller will usually go bad due to dry rot from non-usage, rather than being worn out from excessive usage, and can also be damaged from running motor with insufficient water supply. When replacing the impeller, make sure to apply a thin layer of light weight grease to the inner surface of the impeller housing.
What does it mean when your thermostat is stuck?
What it means for the flow of the water, if your thermostat is stuck closed like this, is that water will come up, it'll come out the tell-tale, all these water jackets will fill, presuming they're not blocked with anything, then the water will get to the top here where the thermostat is and it'll stop.
Can you have a really good telltale and still have a motor overheating?
So you can have a really good telltale and still have a motor overheating. The real job of cooling the outboard comes when the water goes down these other holes here, because they lead to the water jackets around the Pistons. So I'll show you, I'll sort of shine the light and show you how that works.
