Raw water pickup problem

[NateZ]

When i put my boat on the trailer last, right before i shut it down i checked to see how the water was flowing out of my through hull exhaust, which it was normally. However, when i got home and hooked up the ear muffs to flush the motor, it wouldn't run any water through the motor.... Took a look at the impeller but it was in fine shape. (I had just replaced it the week before i used the boat)

I took the hose from the raw water pump to the thermostat housing off of the thermo housing, connected the hose and backflushed it, water came out the drive at what looked to be an ok rate. Reconnected everything and fired it up, no water flow.

I then disconnected the line from the transom to the raw water pump and hooked up an extension so it could pick up water from a trash can outside the boat, fired it up and water flowed through the motor normally. So it seems the problem is definitely in the transom/outdrive... Anybody have any ideas?

Nate

 

[Fishermark]

Re: Raw water pickup problem

What outdrive?

 

[NateZ]

Re: Raw water pickup problem

Ooops sorry thats probably important. It's an 88 mercruiser bravo one 7.4L

Nate

 

[NateZ]

Re: Raw water pickup problem

Anybody have any ideas?

 

[Fireman431]

Re: Raw water pickup problem

Garbage, weeds, etc in the outdrive, maybe? Putting the hose & muffs on might have pushed whatever was in there up far enough to block the water flow.

 

[TilliamWe]

Re: Raw water pickup problem

Nate, it's possible that you were sucking you garden hose flat. Bravo pumps suck HARD!

 

[NateZ]

Re: Raw water pickup problem

Can't be, water was spraying all over the drive out of the muffs as if the engine was off, normally running the drive sucks it all up and no water comes out of the muffs around the drive at all. Also, i had the hose hooked up directly to the raw water pump inlet hose and it worked fine. There is nothing in these drives, i doubt there is any garbage in there, I'm thinking the hose from the gimbal to the transom is kinked somehow or one of the o-rings between the gimbal and the upper housing or the o-ring from the lower unit to the upper housing is leaking air...

I've found allot of instances on this site and more of people with the same setups having problems just like this one, unfortunately most dont post their solutions or it turned out to be the raw water pump. I was going to put a new impeller and inspect the pump again (housing is 4 weeks old) just for the heck of it, but after it worked so well with the hose extension and the trash can outside the boat bypassing the lower unit i doubt the raw water pump is my problem...

Going to investigate alittle more today.

Nate