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Hi,
When i flush my OB on the hose after taking boat on trailer, is there any chance that pressure on the hose pushes water to cylinders when engine is idling?
I start engine then turn water on and first cut water off then stop engine. Asking because all 3 cylinders have that gray water/oil emulsion.
Or where it goes to cylinders? Im confused!
Short answer: No. Flush all you want. Only if water flows "uphill" in your area would you have a concern with flushing an outboard engine with the engine either running or not.
Exception: IF your exhaust baffle area has a leaking gasket that seals against the exhaust cover OR you have a cracked cylinder block or sleeve, you could see water intrusion to the combustion chambers/cylinders while using a flushing hose.
Persona Watercraft (SeaDoos, Waverunners, etc...) have a water cooled exhaust pipe that requires the engine to be running to push the water/exhaust mixture out. If you flush them (the older 2-strokes anyway) you can fill the exhaust system with water and can flood the engine with water.
Okay, thanks!
when flushing, you MUST turn on water first as high as the tap can go, then start engine. when turning off stop the engine before taking hose off.
or you will blow a head gasket 100%.
Also just a quick simple start up will destroy the water pump impeller if no water is already going to it. never ever run the motor with no water, not even for a second....
they destroy real fast if run dry. you must run water through the impeller before starting then switch off motor because impeller turns with motor all the time
you only have the motor running so the water pump pushes the water up the intake pipe, and your water pump pushes a lot more water than your tap can.
this is why never run engine over 1500 on the hose/muffs on the gearcase for more than just a few seconds.
if you want to run engine faster than 1500 rpm then put in a tank or barrel.
sometimes I like to run the motor for say 20 minutes after it has been sitting for a while to charge up battery and clean out the water galleys, so I use
a big plastic water tank with hose running into it all the time to keep it cool and fresh.
if you dont run a hose all the time to it the water gets very warm after about 20 minutes from exhaust and warm water from engine
here is a tank test i done a couple of weeks back, first run this year, even on last years fuel with a little extra oil just to burn it up.
with running in the tank at idle the engine runs at 60 deg c and stays at that temp.
https://www.youtube.com/watch?v=KiN8772sGXc
this shows the tank size I use for testing, I can also use this on my engine stand as it fits on the stand too.
stand is on wheels so I can move test tank and stand, or put tank on a pallet truck.
if you have water and oil mix again you have head gasket problem, or warped head or deck on block is warped.
or you have a bad seal on the adaptor to the block !!!!
next time do head gasket with no copper spray , that might be the problem ? just a thought.