496 Mag Seawater Pickup Pump??

[davis777]

Hey Guys,
I have a 496 Mag with a bravo 1 drive. Engine has 160 hours on it and is 9 months old. Freshwater cooled standard on this engine.
I hooked up the hose today just to bring the engine up to temp. I try to do it every 3 weeks or so during the winter months.
No water was being cirrculated through the engine and out the Corsa transom exhaust tips. I tried turning the Captains Call off and exit through the drive and still no water coming out the drive. The exhaust risers got hot and usually as you know they are warm to the touch, not hot. I only ran the engine for 1 Minute or less as I noticed the problem.
Could this be a Seawater pickup pump problem? Does the Bravo 1 drive have an impeller in it?
Any help before my Sea Ray Dealer hammers me would be great. Thanks, Robb

[Havasu Hangin']

Usually, the hose will force water in...even with a bad impeller. However, I'd change the impeller quick like...it's easy enough.
http://www.speedwake.com/upload/showthread.php?s=&threadid=18967
I used to do mine every season- cheap insurance to prevent getting to the ramp and having to turn around.

[davis777]

Turns out that after it has been sitting for a while I just needed to give it some RMPs a couple of times and it started pulling in water and running just fine on the hose.
Thanks for the tips though.
R

[Havasu Hangin']

Glad to hear it.
To be safe, I'd still consider at least inspecting the impeller. They are just rubber, and should self-prime no matter how low the RPMs. If it didn't, air was probably getting past it (and maybe running dry).

[purrfecttremor]

Sounds like the impeller was running dry and I would replace it just in case.

[Sotally Tober]

I believe your bravo does not have an impeller. My 496HO w/BIII has a seawater pump. It is driven by the belt on the front of the motor. If you are facing the belt (looking towards the back) it is the lowest left side pulley. It will have 2 blue plastic plugs to remove to drain it. Glad you got it fixed.

[92562]

This is common on all of the new design pumps. They are not the same as the old "change impeller every season" pumps. Per Merc spec, the new pump should be disassembled and inspected for wear every 3 years or 300 hours, whichever occurs first.
The first time it happened to me (dry pipes) I was very alarmed. Just as in your case, by bringing up the RPM past 1500 got the water going just fine. A standard hose will not usually make enough pressure to prime the new style pump. I used to change the impeller on my 454-B3 every season, regardless. This new design is set up to be more idiot-proof, which is perfect for me!

[shadow]

This is common on all of the new design pumps. They are not the same as the old "change impeller every season" pumps. Per Merc spec, the new pump should be disassembled and inspected for wear every 3 years or 300 hours, whichever occurs first.
The first time it happened to me (dry pipes) I was very alarmed. Just as in your case, by bringing up the RPM past 1500 got the water going just fine. A standard hose will not usually make enough pressure to prime the new style pump. I used to change the impeller on my 454-B3 every season, regardless. This new design is set up to be more idiot-proof, which is perfect for me!
3 years or 300 hrs?Good luck!

[92562]

I'll probably change mine at 200 hours, but I'm not joking. The latest Merc Service Manual for 8.1L engines says, "3 years or 300 hours, whichever comes first." My guess is the new impeller is something other than rubber.

[shadow]

Nothing new about the impeller,Still rubber.
Not to mention the housing they ride in,the brass plate wears and will most likely need to be machined from wear.
I'm on my 3rd impeller since 02,last one came out in pieces.My boats never been started out of the water or without water.
Not doubing what you've heard,but i'd like to see it in print from Merc 3yrs or 300 hrs.I've never seen or heard of an impeller with a 3yr or 300hr life.

[phebus]

How much did your boat cost? Cheap insurance replacing the impeller every year.

[92562]

OK, so I'm bored!
http://www.***boat.com/image_center/data/520/2442Photo0005.jpg
The previous page has oil changes, etc. This is the only mention of the seawater pump in the maintenance schedule.
The main reason for my post was to point out that at idle, I have seen the "dry pipes" situation on several boats with the new style pump.
With the money I've spent, I couldn't let mine go that long unchanged!
-----Rob

[purrfecttremor]

IT doesn't matter what the manual says.My 1st went out at 36 hrs and burnt the new cheap brass housing out at 36 hrs!!! never ran out of water and that cheap housing is 500.00!! change the impeler every year.Any service shop will tell You the water pump is the weak link on the 8.1.Good luck!!!!!!

[JB in so cal]

I replaced mine at 106 hours, and like Shadow said the housing is what will wear. Mine had to be replaced (under warranty) as well. There was scoring on the brass top and bottom pieces.