Run engine without prop?

[astronutski]

I just had a curiosity question. Is it safe to test run the engine/drive on land with the prop off? Or is that giving no resistance for the engine which could cause overrev or something bad?

Of course I mean using muffs and running water.

 

[flipbro]

Its fine to run with no prop on land.

 

[achris]

In the Merc owners manual it actually tells you to remove the prop 'for safety reasons' whenever the engine is run on muffs. The rule with muffs is nothing more than 1500rpm, and watch the water temp.... I also watch one more thing. The water 'out flow' from around the muffs themselves. If you have no water coming out from around the muffs, one of 2 things. Engine speed too high, or water pressure too low (turn the tap on more). Don't let the pump try to draw more water than is available (that's how you end up cooking the impeller).....

Chris........

 

[spoilsofwar]

The prop on or off the shaft is insignificant to the engine and drive. The load comes from the prop pushing water, not the prop's weight. If anything, removing the prop is smart from a safety standpoint when running the motor in the driveway.

Be careful about running on muffs and in gear. Keep the RPMs low, and do it just long enough to test whatever you're testing.

 

[astronutski]

Great, thank you all, makes complete sense.