Mercruiser Water Flow Problems

[twgin]

Hello and thanks in advance for any help,
Mercruiser 5.0 mpi, Bravo III, engine serial 0M360353, 2002 vintage, multipoint drain

This boat hasn't been run for a few years, when I started it using muffs the pump wasn't taking any water, so I rebuilt the raw water pump (old impeller was trashed, I am pretty sure I got all the pieces out as the weight of the pieces matched the weight of the new impeller within a few hundredths of a pound).

So now upon starting, the pump is taking water through the muffs, I would estimate between 4 to 8 gallons per minute, based on the time to fill a three gallon household bucket). After about 30 seconds the bilge pump turns on and the water is ported out the side. Sure enough, the water is pouring out of the engine, seems to be coming out from the underside of the starboard exhaust/riser, some water also from the port exhaust/riser, but not as much.

I have read elsewhere that when running with muffs, not much water will make it to the propellor exhaust, and that what water there is will not be equally distributed to both sides of the engine (not enough water from the muffs). But what I am seeing can't be correct

The boat has always been a freshwater boat, florida and california...

Thanks,

twgin

 

[greg82255]

Re: Mercruiser Water Flow Problems

Water flow from a hose obviously won't be as much as from the lake, but no water should ever be flowing into the bilge from the engine. Are you sure all the drain plugs are in and all the hoses are connected with properly tightened hose clamps? You could also possibly have a core (freeze) plug that popped out.

 

[Don S]

Re: Mercruiser Water Flow Problems

Pull the exhaust manifolds and inspect the block and manifolds.

 

[Bondo]

Re: Mercruiser Water Flow Problems

Sure enough, the water is pouring out of the engine, seems to be coming out from the underside of the starboard exhaust/riser, some water also from the port exhaust/riser, but not as much.

Ayuh,.... Either the drain plugs weren't put back in,...
Or,...
They were never removed, 'n the block Cracked...

 

[IanFS]

Re: Mercruiser Water Flow Problems

Is it possible that the cooling hoses underneath the manifolds haven't been tightened, as already suggested and as Bond o says, the taps on the drain plugs may still be open.