Skip Drive Impeller in Full Closed Cooling System?

[chriscor]

Dear All,

I am running a full closed cooling system (2005 4.3 MPI) with the motor mounted water pump. Drive is an Alpha One Gen II. (water hose cut by manufacturer). May I leave out the Impeller in the Drive? Is there enough water flow to cool the drive without the Impeller attached?

Thx
Christian

 

[Bondo]

Re: Skip Drive Impeller in Full Closed Cooling System?

Dear All,

I am running a full closed cooling system (2005 4.3 MPI) with the motor mounted water pump. Drive is an Alpha One Gen II. (water hose cut by manufacturer). May I leave out the Impeller in the Drive? Is there enough water flow to cool the drive without the Impeller attached?

Thx
Christian

Ayuh,.... Ya Could,.... But I wouldn't,.... More coolin' for the drive is Way Better than not enough,...

 

[Fun Times]

Re: Skip Drive Impeller in Full Closed Cooling System?

The nice thing about the alpha Gen 2 impeller is that under basic general use (without going through a bunch of debris) it will typically out last the engine mounted impeller by many years or hours. It is not that uncommon to pull a 7 year old alpha Gen 2 impeller and still think to yourself that if needed, it still could be reused.

 

[JustJason]

Re: Skip Drive Impeller in Full Closed Cooling System?

The impeller in the sterndrive is more than capable of cooling the engine, and pushes plenty of water. If anything, you would get rid of the engine mounted seawater pump, and keep the pump in the drive.

To add to that. When you are up on plane, the upper half of the sterndrive is out of the water. What helps cool the upper is the water passageway. If you remove the impeller, you take away the uppers ability to cool itself. On top of that, there are seals just below the water pump impeller. Those seals will no longer have water directly around them to help cool those seals. And the hotter any seal runs, the less life it has.

You really have 2 choices here.
1. Keep the alpha pump and get ride of the engine mounted pump.
2. Just replace both impellers.

 

[Scott Danforth]

Re: Skip Drive Impeller in Full Closed Cooling System?

The impeller in the sterndrive is more than capable of cooling the engine, and pushes plenty of water. If anything, you would get rid of the engine mounted seawater pump, and keep the pump in the drive.

only with a half system not with a full system. the full system needs more flow than the raw water pump in the alpha can put out. so it uses the engine mounted pump from the Bravo.

 

[JustJason]

Re: Skip Drive Impeller in Full Closed Cooling System?

only with a half system not with a full system. the full system needs more flow than the raw water pump in the alpha can put out. so it uses the engine mounted pump from the Bravo.

You think? This is a V6, not a V8 (and not a big block) And it's the gen 2 drive. High volume output. A lot of the aftermarket kits (like the seakamps) do full cooling on just the gen 2 impellers output.

 

[Scott Danforth]

Re: Skip Drive Impeller in Full Closed Cooling System?

I dont think, I know. I used to work for for the company that makes the HX's for Mercruiser, Volvo, Cat, Cummins, and more.

the impeller in the Alpha gen 2 produces just under 20gpm at 20 psi restriction. the Bravo puts out closer to 26gpm at 20 psi if I remember my pump curves

 

[JustJason]

Re: Skip Drive Impeller in Full Closed Cooling System?

Interesting. I've never seen 2 pumps on the V6's. (V8's you get no argument from me, but still have no idea how the aftermarket guys do it, I don't install them, I only know they exist).

Do you happen to have any PDF's on the various pumps output at higher rpms? All that's in the books is low rpms output.

 

[Scott Danforth]

Re: Skip Drive Impeller in Full Closed Cooling System?

If memory serves me, the 4.3MPI/Alpha with full system was a kit that included the Bravo pump. In this case i believe the leg impeller was disconnected and I believe that a transom pickup is used. However if the flow is coming from the leg, then the impeller needs to be there because the bravo pump will not pull thru the alpha waterpump.

the Half system was from the factory using only the Alpha Impeller, however I do not recall the half system on the MPI motors.

I have to go into my archives to see if I kept any of the pump curves. I know that the ITT jabsco pump curves are available online

 

[chriscor]

Re: Skip Drive Impeller in Full Closed Cooling System?

Thank you Gentlemen. I think he is going to stay in it's place. Nearly as good as new.

 

[dan t.]

Re: Skip Drive Impeller in Full Closed Cooling System?

only with a half system not with a full system. the full system needs more flow than the raw water pump in the alpha can put out. so it uses the engine mounted pump from the Bravo.

Not the case, I run a 350 magnum with full closed cooling using just the pump in the leg (alpha 1 genII). It runs at 180 F. consistantly. I have run this set up for 5 years with no problem and never had an overheat.