zog02

I have 7.4 attached to a Bravo II drive. Last weekend I was doing my normal flushing routine after being in the salt water. I have the flushing system that the hose plugs into (no muffs required). Where I hook up the hose there is a valve that allows water to flow from the hose into the motor. It is normally shut so water cannot backflow when the boat is running in the ocean. I was in a hurry (stupid me) and forgot to open it back up when I plugged the hose up. Basically the hose was turned on but no water was entering the engine becasue I had that valve turned the wrong way. I started the motor and ran it for 15 to 20 seconds before I realized that no water was coming out the back. As soon as I realized I flipped the valve and everything seemed fine. Water started flowing out the exhaust like normal. Is there any way to tell if I damaged my raw water pump? I know what I did is not good for it but I don't really want to replace it if it doesn't need it. Thanks for the help!!

FOUNTAINATLAST

Without visual inspection its hard to really know. Best suggestion hook up your water let the engine run awhile watching the temp closely. If it still seems to be running at the correct temp your probably ok. Like I said visual is best but theres a chance your ok, its happened to others including myself before. There is some forgivness in those pumps.

hillbilly24

More then likely you didn't do much harm, 15-20 seconds isn't much. You may want to change the impellor just for piece of mind. If a piece did break off you want to find it, I have seen them stick T-stats both open and closed, plug P/S coolers and all sorts of other fun stuff. If it is pumping fine now though, you would probably be ok to leave it alone though. Just do whatever makes you feel secure.

Roger 1

I`ll bet any money that it`s ruined. I would remove it and inspect it and I would`nt doubt that the housing is shot as well. Also, your going to need to get the remnants of your impeller out of the cooling system. That means removing the oil cooler and cleaning it out. Unless your a do it yourselfer You might want to take it to your mechanic and have him take care of it for you.

zog02

My plan was to get the hose out tomorrow and run it for 10 or 15 min. Like you said if it stays cool I think I will be ok. I am planning a trip next weekend so I want to make sure it is working correctly. I am glad to hear that I am not the only one that has done this. I felt so stupid because an extra 5 seconds would have saved a lot of worrying. Thanks for the replies!

FOUNTAINATLAST

S**t happens, I was running my old boat with the hose on warming it up to change the oil never noticed the muffs had fallen off until I looked the exhaust and saw no water. Sure enough burned it up! Changed it the next day before going out, worked great all day UNTIL!!!! I backed my trailer in the water, my lovely wife pulled the boat on the trailer and up the ramp I went. Got out grabbed my cleaning supplies heard a motor running and thought thats not good been there done that glad mine was just done, just to find out my wife forgot to turn the motor off!!! UHHHHH!!

Needless to say two impellers in as many days, lesson learned??? MAYBE

J-Bonz

iTrader: (3)

I have to agree with roger 1, the impeller is most likely shot and should be replaced. The merc tech manuals claim that 20 to 30 seconds will ruin the impeller. Checking it while running on the hose is not a valid test due to the intake pressure into the pump, while on the hose, is much greater than the pressure the pump is actually seeing while oppperating in the water.

customryder

my GUESS is its ok... their is always a slight amount of water in the hose & housing. but dont take my word for it.

Poorsche

Running on the hose won't answer the question about the pump/impellor because the water is under pressure. You ned to put the boat in the water and let the pump do the "work" rather than the hose. If you can't put boat in the water rig up a resevoir that you feed with the hsoe so you can eval pump performance.

Doolars to donuts says impellor damaged pretty certain, pump housing could be chit as well.

I like Too Old's solution--it's cheaper than most raw water pumps in addition to run dry capability.

cig1988

I would take it apart & inspect. If it is damaged & you run water thru it, you'll get chunks of rubber from the impeller clogging up the system. Does'nt take much for that impeller to sefl destruct.