How to run Mercruiser 5.0 mpi sterndrive with dual water inlets out of the water...

[mhound]

How to run Mercruiser 5.0 mpi sterndrive with dual water inlets out of the water... I see a lot of posts talking about earmuffs, but no info about supplying water to the second inlet, which is a smooth thru hull fitting, that leads to a water pump. Maybe earmuffs alone would be enough, but I'm worried that the water pump would be damaged.

M

 

[Fun Times]

Is the dual water pickup on the stern drive itself or is there another pickup mounted to the boat?

One needs to be blocked/covered so it won't suck air and damage both the impeller and impeller housing.

 

[mhound]

The second inlet is in the bottom of the boat with a completely separate water pump from the leg water pump...

 

[Scott Danforth]

your boat has a heat exchanger doesnt it. it was added after the fact (posibly dealer installed) along with a bravo style pump. in that case, two hoses, one set of muffs, the other you plumb to where the thru-hull pickup is on the inside.

 

[Bondo]

The second inlet is in the bottom of the boat with a completely separate water pump from the leg water pump...

Ayuh,..... Which drive is behind this motor,..??

If ya got 2 water systems, one of 'em ain't doin' nothin',....

If this is a Bravo drive, there is No water pump in the drive, 'n the thru-hull fittin' is the only water feed to the motor,....

If that's the case, ya gotta plumb water into the Pump, not the drive,....

 

[mhound]

This boat is a 2352 2005 Trophy Walk around.. with 5 liter MPI mercruiser Alpha One Generation two There used to be a sign somewhere on the boat (I cant find it now) saying that this boat has dual water inlets, or words to that effect, It is completely closed cooling with heat exchanger etc. I want to check everything while its on the trailer before I launch into salt water for the season.

M

 

[Fun Times]

As mentioned by a few, because you have an Alpha stern drive, there usually is an impeller within the drive itself to help cool the drive and you'd need to put a set of ear muffs on the lower gear housing to keep from burning up the rubber impeller inside should it still be there.

There is a small chance that the impeller was removed by someone but to be safe it's best to run it using the muffs until you know for sure when you get around to inspecting/replacing the impeller sometime as a preventive maintenance.
Usually it is recommended that the inlet hose behind the bell housing next to the U-joint bellows (portside) be cut so the water will flow through the drive and out into the body of water to help keep the drive cool but it "shouldn't" be being used as a cooling system for the engine since you have an engine mounted pump.

In your case the engine mount impeller is typically the more important one to keep healthy and in order to run the engine at home you'll need something like a fake a lake inboard engine flusher seen here using a toilet plungers design, http://www.bing.com/images/search?q=fake+a+lake+inboard+engine+flusher&FORM=HDRSC2

 

[alldodge]

Take some pics please of the bottom of the boat

 

[Scott Danforth]

to further expand on post #4, and post #7, if your boat was ordered from the factory with a heat exchanger, it would have been supplied with a bravo drive. however it was spec'd with the alpha drive, and the heat exchanger added by the dealer. post #7 reflects the normal post production installation instructions for a factory mercruiser full system hx. The kit includes the decal that you noticed and mentioned in post #6

 

[mhound]

Today I bought a toilet plunger/inboard motor adapter as suggested by "Fun Times", but I found it doesnt really work, because I cant get a seal, due to another fitting being right beside the inlet. (I think its the bait tank water inlet). I guess the only way to do it is to plumb in an adapter inside the boat.

M

 

[thumpar]

You can put in a fitting on the intake hose but you will need to put in a valve so that it doesn't just drain out the bottom.

 

[Fun Times]

Take some pics please of the bottom of the boat

I bought a toilet plunger/inboard motor adapter but I found it doesnt really work, because I cant get a seal, due to another fitting being right beside the inlet. (I think its the bait tank water inlet).

Any photos available?

 

[mhound]

I talked to a Merc Rep, and he told me the only way to solve my problem, is to put a removable fitting on the intake hose, so you could disconnect the hose, and put it in a bucket, so you can fll the bucket with your garden hose, and the water pump can suck water from the bucket. This ensures you have plenty of water available to the pump, which I'm told is very expensive, and would be damaged if it runs dry.
For now, I have abandoned the idea.... Maybe next year....

 

[thumpar]

Where does the hose from the thermostat housing go? I probably runs through a power steering cooler but does it come from the transom or the thru hull? A bucket is not going to help. It will suck air from the thru hull.