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

Edward R. Cozzi

Never should you find an impeller in any Bravo drive.

Remove the belt and see if the raw water pump turns easily. If it does, you need an impeller kit. If you feel resistance to clockwise turning of the R/W pump pulley, look elsewhere for now.

Good luck and keep us posted.

Outdrive1

You need an impeller. You sea pump is on the bottom left hand side of your engine (looking at it from the front). It's only nuts and bolts, not to hard to change. Make sure that you take the old impeller out and re asemble it on your work bench. If you don't have all the pieces you will have to follow your hoses and back flush the system until you get them all. If not you could change the impeller and still have a blockage. More than likely they will be in your oil cooler, but I'm not sure of the hose routing on the closed cooling system.

Outdrive1

BTW, your sea pump is on the bottom left hand side of your motor(looking from the front).
Take your belt loose.
Remove hoses, mark one of them with tape so you don't put them on back wards.
Unbolt sea pump from bracket.
Take apart on your work bench, remove old impeller (make sure you have all the pieces).
Install new impeller, coat fins with some grease so it wont get torn up the first time you fire it up dry.
If you don't have all the pieces trace your hoses and back flush with a garden hose or if you get lucky sometime air pressure will do the trick.
Put your pump back on the bracket.
Install your hoses.
Install your belt and you are done.

The only other thing to think about is that you could change the entire plastic housing kit instead of just the impeller. (30 dollars verses 80 dollars) Check to see if yours has any cracks when you disassemble it. I change my housing every other time I change the impeller.

davis777

Thanks for the information! I really appreciate it. Of course I am not an expert, so when I did not see any water coming out it got my heart racing a bit. I am glad to know it is a easy fix and I will be very aware of the impeller pieces that may still be in there.
Thanks Guys.
R-

Sydwayz

If you are going to go through the trouble of removing the sea-water pump to replace the impellor; (which you need to do) go ahead and install a T-fitting into the input hose of the pump, so you can directly hook up a garden hose to the inlet side, and not have to EF around with earmuffs anymore. I did this on my twin 496HO application, and there is nothing better.

BTW, the SW pump assembly on the 496 engine is BRASS, not PLASTIC. Hence total replacement pump assembly is $400, not $80 like the 502 blocks. Since the SW pump assembly is now brass, it does not require replacing unless the appearance of SEVERE damage (much less likely with brass).

Its also easier to wrap a zip-tie (tie-wrap around your impellor to install it. Get the veins all going the right direction, and bent down by sinching your zip-tie down. Use the lubricant mentioned above to slide it in easier with fewer busted knuckles. I normally use a bit of silicone spray.

Do a search on here. There are more detailed tips.

GOODT

STUPID QUESTION.... Did you release the pressure from draining the water out of the block if you dont release the pressure the pump will not draw water !!!!!

davis777

When loosening the serpentine belt on the 496 Mag where do you start? The manual says "loosen the 5/8" locking nut on the adjustment stud"

Where is the adjustment stud? By the Alternator?
R-

Raylar

Sydwaz has it almost right. the pump is brass. Be careful just changing the impellor. The problem that shows up in these brass Merc. pumps is that the housing, especially the back plates get deep score marks and if you just replace the impellor, you many times won't develop the flow and pressure needed. The back plate can be re-machined to make it flat smooth again, but not so for a badly scored housing. The 496's have a pressure sensor on the pump housing and if the raw water system is not developing enough water pressure it should set a code and set of a beep when running. If this is the case and the raw water temp gets to hot, the exhaust manifold water temp sensors are set to throw a code and set a beep at 180 degrees plus. If impeller is missing pieces or coolers like oil have debris clogging them, they should be backflushed to get all the deris out. Luckily, the Merc Guardian system on the 496's and clossed cooling systems will help you from grossly overheating and destroying yourmotor. If you are not sure of your troubleshooting skills get a scan tool for a bout $400. a few trips to a Merc dealer can be more than that just locating a problem. Just some info.

Ray @ Raylar

davis777

So I followed Edward Cozzi's advice and loosend the belt and tried to turn the pully and there was moderate resistance.

I buttoned everything up and decided to try it again today.
I read in some of the other posts that you need to give it some RPMs as well as give it a while. Well that made me nervous but it worked. Started to pull water and run just fine.
I feel like a total rookie, which I am, but it sucks to feel that way. Guys, thanks for all the tips. I do have a question though.

When you pump air into the 496 and subsequently all the water out, is it hard on the impeller when you fire it up after the motor has sat empty for a month or so??

Thanks again,
Robb