Flushing Mercruiser
 

I am new to I/O's and have a 4.3 Mercruiser with an engine mounted raw water pump. To flush the engine with water while warming the engine and to later add antifreeze to the system, do you do this via muffs on the outdrive or connect directly to the water pump for one or both procedures? I am assuming that to flush with water from a pressurized hose, you would use the muffs and to use a gravity feed system for the antifreeze you would connect directly to the pump but would like to hear some comments from those more experienced at doing this. Thanks

Re: Flushing Mercruiser
 

Muffs all the way.
Otherwise you'll trash the impeller in the leg.

Re: Flushing Mercruiser
 

Andy, I understood that there would be no impeller pump in the outdrive if there was a motor mounted raw water pump. Am I wrong?

Re: Flushing Mercruiser
 

What leg?
If it's an Alpha 1 then there's an impeller in the leg and a circulation pump on the front pulley of the motor.

Re: Flushing Mercruiser
 

I acquired this boat recently after a relative passed away, however, it is in storage and bubble packed at a marina up here in Canada so I haven't actually seen it. I have been told that there is definitely a raw water pump mounted on the engine (in addition to the engine circulating pump) so I believe the outdrive is a Bravo.

Re: Flushing Mercruiser
 

Here is my setup for winterizing my mercruiser 3.0 L
works without any leakage of anti freeze.

Re: Flushing Mercruiser
 

Great Pics. I have saved them to my Mariah file and will definitely refer to them for future flushings. Thanks very much.

Re: Flushing Mercruiser
 

You are welcome,
Plase note!, that its important that there is enugh flow thru the hose, and there is a second air vent hole in the antifreeze container, otherwise you will ruin the impeller!

i also have the drawing with measurements, for the cardboard plate, used under the haul on the picture
i wlll post them later here,