warming an outboard up

scoobeb · Oct 23, 2011

I have a curious question on warming an outboard up.What i wanted to know was how long does it take a 15hp 2stroke yamaha or any outboard if (it's the same time)to be 100%properly warmed up in both the cold weather and warm weather.I have heard about a thousand times it may be ready to go as in like 1min,3min etc but does anyone have an idea of how long it needs to be just right to go before hitting the throttle.

For hot and cold temps.Also does a 4stroke differ from a 2stroke in warming them up?Plus can you actually let it run for to long at idle warming it up were it would do damage or once broke in you can let it sit running for as long as needed without huting the motor?Thanks for any info.

jasper60103 · Oct 23, 2011

I don't have the answer, but I think I tend to pamper mine. My motor is cold blooded and tends to sneeze a little at cold start. I'm usually in no hurry. By the time I get my life jacket on, and settle in the drivers seat, its idled for a minute or two before I pull off slowly from the dock.

crazymanme2 · Oct 23, 2011

In the warm weather couple of minutes is fine.In the cold it's another story,maybe 3-4 minutes or more.You can't leave them idle too long.

TNtroller · Oct 23, 2011

4strokes would probably be closer to the 4 cyclinder in your car, just go easy for a minute or 2 and should be good to go. 2strokes, I usually let it warm up until it will idle good w/o any choke or fast idle assist, then go easy under way for a few more minutes. Warming up a 2 stroke on choke for too long will foul the plugs as will letting it just idle for too long. 4 strokes don't have the oil/gas mix, just gas so it's more like a car engine.

PSG-1 · Oct 23, 2011

It's definitely never a good idea to just crank up and then gag it wide open with any motor without warming up first. Heat needs to be equally distributed and dispersed through the block and the moving parts, and oil needs to be circulating before those moving parts are brought up to speed.

I've heard outboard mechanics say that you definitely want to let the mercury optimax engines warm up, gagging them from a cold start will likely cause catastrophic engine damage (not sure exactly why, but I think it has to do with the oil circulating properly)

Also, you should be careful about flushing a hot engine with cold water from the hose, the temp differences can sometimes crack a block, I've seen this happen with jet skis. An engine should be allowed to cool down somewhat before flushing.

Pappy · Oct 24, 2011

With a two stroke the engine will run its warmest at idle. This is by design so as to minimize moisture in the clyinders during prolonged idle in cold water and primarily to improve idle quality by helping to atomize the incoming fuel/air mixture at idle. Nothing wrong with idling a two stroke for as long as you want to. They should run, if thermostatically controlled, somewhere in the 135f range give or take. For warm up I would say two to four minutes depending on water temp.
The issue with running any engine hard that hasnt warmed up is that the block is cold and therefore at minimum tolerances and the pistons, if run hard immediately, will be hot and fully expanded before the block can get up to temp. This creates a high wear situation until the block warms sufficiently. This holds true whether or not the engine is a 2-stroke or a 4-stroke. With a 4-stroke, from a cold start, you also need to allow time for the crankcase oil to warm so they will take a little longer.
Running cold water through a warm outboard is a non-issue, period! This happens routinely throughout the engine's life anyway. The aluminum has no problems expanding and contracting as needed. When a two stroke has been run at idle and is fully up to temp and then shut off it will continue to climb in temp for a few minutes anyway. When re-started in cold water the thermostat will decide how much and when to allow water to circulate through the block.

crazymanme2 · Oct 24, 2011

With a two stroke the engine will run its warmest at idle. This is by design so as to minimize moisture in the clyinders during prolonged idle in cold water and primarily to improve idle quality by helping to atomize the incoming fuel/air mixture at idle. Nothing wrong with idling a two stroke for as long as you want to. They should run, if thermostatically controlled, somewhere in the 135f range give or take. For warm up I would say two to four minutes depending on water temp.
The issue with running any engine hard that hasnt warmed up is that the block is cold and therefore at minimum tolerances and the pistons, if run hard immediately, will be hot and fully expanded before the block can get up to temp. This creates a high wear situation until the block warms sufficiently. This holds true whether or not the engine is a 2-stroke or a 4-stroke. With a 4-stroke, from a cold start, you also need to allow time for the crankcase oil to warm so they will take a little longer.
Running cold water through a warm outboard is a non-issue, period! This happens routinely throughout the engine's life anyway. The aluminum has no problems expanding and contracting as needed. When a two stroke has been run at idle and is fully up to temp and then shut off it will continue to climb in temp for a few minutes anyway. When re-started in cold water the thermostat will decide how much and when to allow water to circulate through the block.

Very well said Pappy =D>

scoobeb · Oct 25, 2011

Yea i was going to say that if the block would crack putting cold water on it when a motor was hot we could never own outboards.When in the water or ocean it's cold in the winter or fall as the water temp gets close to freezing,a ton of people shut down their outboards to fish then they restart sometimes asap or even a few hrs later and the water will still be cold going through a hot motor.If that was the case every outboard block would crack one time or another.

But back to the right temp.So i would say 4 minutes sounds good then.I notice when i start my outboard by about the 4th to 5th minute the idle comes way down to almost nothing,that is when i will take off from the ramp.Thanks pappy and everyone else who chimed in.

.

nomowork · Oct 25, 2011

I think any "carbed" motor takes a little time to warm up. Even my brand new Honda carbed four stroke is finicky upon cold start up. On my tin, I usually let it idle for a few minutes and in that time, I use the trolling motor or the oars to get out of the launch area into deeper water so as not to add to the congestion.

GreatWhite · Oct 25, 2011

I let ALL my engines warm up....no matter if it is a car, boat or airplane....

Engines have dissimilar metals, expand at different rates, etc...

But really, what does it hurt to sit at idle for a min or two, while you are getting the fishing rods rigged, turning on the graph, etc....

After a min or two of idling, I put her in gear and idle away from the dock for the first few hundred feet (load on the engine accelerates heating up), then slowly roll on throttle, getting to cruise power in about 10-15sec....

Again, no matter what the engine, that is how I have always done it....and see no reason not to....

Garrett
(who yes, is a mechanic by training and experience on everything from cars to boats to aircraft)

warming an outboard up

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