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View Full Version : No cooling water through bravo drive???



zimm17
03-14-2007, 02:35 PM
I'm not getting water to my raw water pump. I just dewinterized the boat. I'm using the quicksilver skewer muffs that worked just fine every other time I ran the boat in the yard.

I can get hose water to go from the raw water line out the drive pickup holes, but I have to cup my hands around the hose and build a little pressure up.

I removed the raw water hose- and still no water up through the fitting on the drive- even while holding the muffs tight on the drive with LOTS of water pressure on it.

Any ideas?

mrfixxall
03-14-2007, 02:52 PM
Try putting the hose into the hose from the raw water pump and force it through twards the drive..its designed to suck the water in the engine and its kinka hard to force it through all those funky angels,,,up through the drive through the gimbal housing, a curved hose that goes into the inner gimbal then attached to a up sized 1'' hose..

I bet you just have a bad impeller thats all or if your in salt water you may have a build up of hard salt in the ater pickup..

TheFees
03-14-2007, 05:01 PM
Whenever I go to my Mercuiser guys, who have been in the thick of it for 40 years, the first thing they ask me is "When was the last time you replaced the water pump in your outdrive?" You see the problem is twofold: One the rubber paddles that when new, squeeze into the metal surround very tightly. Sitting in that surround, as nature goes, when met with a lot of resistance, constantly over a long period of time, they finally give in, and adjust to the shape that they are put in, which in this case is resting against the metal outer drum. In other words, they lose their strength. Considering that water is not compressable, that pump has to move a lot of water, and without a hard press against the outer cylinder, it can give way a little bit, causing, for lack of a better term, backflow. It doesn't actually flow backwards, but slows down the flow instead.
The other thing is that any time you pick up a few grains of sand, (when is the last time you hit a sand bar, or were backing up in reverse, and churned up some mud-pebbles, placing the cloud of junk right into your input ports) and just a little bit of abrasive could wreak havoc on the surface of the pump.
Look I am not a marine mechanic, had a body shop for 20 years, got licensed as a State Inspection mechanic in PA, but that doesn't mean anything when it comes to boats. I have been servicing my 18 350mag Merc with AlphaSS for 18 years, and have replaced the pump many a time, but I do not want to act like a know it all, cause I ain't :propeller:
While it is out, it will give you a chance to inspect the inner channels, to see if anything is blocked in there too.
I will be curious to read what the guys who really know their stuff in here have to say.
My boat is running a little hotter than it used to. I used to not generally go above 150, and at full throttle it might go up to 160 or so, then quickly go back to 150 at normal speeds. Now I am getting 180 or 190 after only a minute or two at full throttle, then it takes a little longer to get back down to 150. I know, I know it's time for a new set of colectors, and a manifold. Any other suggestions. The thermostat is new. Do the water pumps on the front of the block do a slow degeneration. or are they known to just work properly, and then all of a sudden start leaking? Your help is appreciated. Has anyone ever tried removing the collectors and having them blasted through the channels. My boat is a 1987 with about 600 hours on it, and never, except one night, saw an overnight stay in the water. Fresh water flushed when used, and antifreezed heavily during the winter.

zimm17
03-14-2007, 05:08 PM
Well I removed the suction hose from the raw water pump (engine mounted pump) and I still don't water up from the drive. I didn't think bravo drives had water pumps inside of them. If they do, that's probably the problem.

I'm going to replace the suction hose with a new line- then fill with water and hit it with compressed air- maybe there's a bunch of junk in there.

I just don't understand how I can water to flow out the drive, but not up it? Worked just great before I winterized it.

MOP
03-14-2007, 07:33 PM
Fair chance the hose from the gimble to the shield is kinked and a PITA to change! To check it out trim the drive fairly high and see if the water goes through.

Phil

pmreed
03-14-2007, 07:55 PM
No water pump in the Bravo outdrive, so that's not the problem.

Phil

Pismo
03-14-2007, 08:14 PM
You most likely just need a new impeller. There is nothing in a Bravo drive to break just an empty tube. Backflush it to make sure it isnt clogged.

TheFees
03-14-2007, 09:06 PM
I mentioned the "water pump" in the outdrive, maybe I was using the wrong phrase. At this point, I would like to know, does a Bravo outdrive have an impeller in it? Someone stated that their isn't any water pump in the bravo drive, just a tube. I shouldn't be so concerned about this, but now I am curious. I've replaced the impeller in my Alpha drive several times, the Bravo doesn't have one? It only has a passive tube? No impeller either?

MOP
03-14-2007, 09:27 PM
Alphas and bottom shifter OMC's have pumps, Bravo's, King C amd Volvo do not have drive pumps.

Pismo
03-15-2007, 11:13 AM
I mentioned the "water pump" in the outdrive, maybe I was using the wrong phrase. At this point, I would like to know, does a Bravo outdrive have an impeller in it? Someone stated that their isn't any water pump in the bravo drive, just a tube. I shouldn't be so concerned about this, but now I am curious. I've replaced the impeller in my Alpha drive several times, the Bravo doesn't have one? It only has a passive tube? No impeller either?

No impeller in the Bravo drive, just an empty tube. The impeller is in the raw water pump mounted to the engine, not the big circulator pump in the middle, it is off to the side with a belt driving it, about as big as your fist.

TheFees
03-15-2007, 01:46 PM
Thanks for the information, I appreciate it.

jdp_509
03-17-2007, 08:52 AM
How Often Should You Change The Impeller, With A Bravo Drive?