496 HO Impeller Education
 

Ok, I appologize up front for my ignorance. I have used the search feature and y'all are just operating at a higher base level of knowledge than what I need. I just purchased a 2005 Nordic Rage with the 496 HO Mag. I'm not understanding enough about the cooling system on this motor to know how to run it in the driveway. I know there's a closed sytem, an open system, and a heat exchanger. Here are my questions:

Is there one impeller or two?

When running it in the driveway how does the impeller get lubricated prior to the thermostat opening?

My boat has a nose cone water pickup. The previous owner told me to drop the drive in an ice chest and fill it to run it in the driveway. When I try that the nose cone is in the water but not the holes where the mufffs would be are exposed. Does that stop the nosecone from picking up water?

I've read the winterizing threads and I think I'm good on that process with the exception of the pump for the heat exchanger. I guess if I understand the cooling system better I'll be able to figure that out?

Fogging - how do I do this on an FI motor? I'm planning on putting stabil in both tanks but I get a feeling there's more to it than that?

Thanks for your help and your patience with my education. I got NOTHING with the boat with regard to manuals so I'll be contacting Mercruiser to get the manuals.

BTW - If there's anyone in the Central Texas area, besides the Spicewood folks, please chime in so I know who's knowledgable in the area.

to fog it remove air cleaner,,,you will see a 1/4in air hole in the throttle plate,,,i would start fogging there,,,but it would be the last step,,,one impellar,,,,water is the lub,,for the impeller. just use the air pump until the little green indacators pop up,,,,release and pump up again,,,,,i did it that way for 5 years on my 496 in michigan,,,no promlems,,,,some will run the red stuff through the drive and out the exhasut for extra protection

There are two blue plastic plugs at the bottom of the engine, you can open those too after using the air pump.

Is there water to lube prior to the drive pulling water?
 

Thanks for all your help. I had it running for a short period of time in the driveway yesterday with the mentioned technique, cooler and drive in the water. Like I said the nosecone was submerged but the the holes that the muff would have covered were open and no water was being pulled from the drive. Was that because the thermostat hadn't popped or was it because the holes were exposed to air?

Was the impeller being lubed by water that was inside the engine at this point?

BIG negative on fogging an EFI engine by spraying down the throttle body!!

You have to either:
Mix up a 5 gallon can with 2-stroke oil and gasoline and plumb your fuel pickup line into that tank temporarily.

or

Remove your fuel water separator (or cover to the canister) and fill it 1/2 full with 2-stroke oil.

RTFM. It's in the book.

I've posted several times about winterizing 496s. The ONLY way to do it RIGHT is treat it just like any other engine and fill it with 5-6 gallons of antifreeze via running it through the system. The air pump is ONLY good for a "temporary" winterization to get you through a few cold nights and extend your boating season.

There are pockets of water in the heat exchanger and coolers that will still house water and NOT be pumped out with the air pump system. You will find this out the expensive way in the spring.

If you run the boat without it pumping water you have damaged your impellor, period. Maybe even scored the pump.

The best way to run a dual water pickup (DWP) drive on the hose is with a garden hose connection directly into a T in front of the SWP (sea water pump with the impellor in it)

The second best way is to put shrink wrap tape over the LOWER water pickups (around nose cose) and then run muffs on the upper water pickups like you normally would.

Do I pump then....
 

Ok, so do I pump the heat exchanger, then drain the block on both sides and both exhaust manifolds, close the petcocks, and then pull rv anti-freeze through the drive?

Even if just for half a minute or so?
I'm asking because while running my boat with muffs (Bravo XR with DWP), the tape on low water pickup fell off and it took me a bit to realise that.
Nonetheless, water pressure has always been fine afterwards.
Should I check the impellor anyway?

If it was not sucking water and the intake holes were in the air, then you probably ruined the impeller. The water lubes the impeller.

The water being sucked in works like the air flowing through a radiator in a car.

I wouldn't worry about fogging the engine. It will be fine.

You probably had enough water getting in and didn't damage the impeller. You should change it every couple of years anyway though.