496 sea water pump
 

Beautiful day in Colorado today. All pumped up to get the boat in the water tomorrow. Get everything ready to go. Double check everything and turn on the water and start the engine. Running great, so I hop out hop out and look. No water at all from the exhausts. :( I turn the motor off, double check everything. Take out the blue plugs, no water. ???? Got my lower water pickup taped off, double check the muffs and hose attachments, water to the outdrive is fine. Blue plugs back in and Start the motor again, run to the back of the boat, still no water from the exhausts. :mad: Look in the bilge for any problems and find none. Water pump starts sqealing. Shut the motor off. Water pump is hot. Now what. It ran fine when I winterised it. Drained everything like I normally do the past 3 winters. Engine has only 24 hours on it.

I suppose it's time for a rebuild. I can pull the pump and bring it to a shop. But I'm not sure what the potential problem is yet. Any ideas? Is there an aftermarket pump available for the 496 yet? The boards here have raised a lot of issues with this pump and as long as I'm going to spend some money I'd like to spend it in the right place. Thanks.

Re: 496 sea water pump
 

trashed the impeller. that was the squeek of dry hot rubber against the housing. 5 minutes to swap impellers, 45 minutes and some profanity to get the pump off and open. I smoked one winterizing, replaced it, have to do the other next week.

They should be changed bi-annually if not every spring.

That pump is kindof a PITA to work on...but nothing you can't do.

Twist the new impeller into the housing with liberal Vasaline and then some. It'll keep it "lubed" until it gets water the first time.

Re: 496 sea water pump
 

Thanks Rippem,

I went over to the merc mechanic and they said impeller also. 30 some bucks for the part. I'll get some bandaids for my knuckles tonight :rolleyes: and start in on it in the morning. Hopefully the housing isn't scored or something.

Re: 496 sea water pump
 

I would bet the squeal was the belt slipping on the pulley, that is common as the impeller being rubber will take a set when left to sit a long time. Many times you can loosen the belt a nd break it loose and be good to go, I would try that before you break your butt getting it apart.

Phil

Re: 496 sea water pump
 

it's the impeller.
the squeel was after it had been running and moved no water. that dry rubber will only go around just so many times before it gets hot, breaks apart, and the hot dry fragments squeel getting dragged around against the housing by what's left intact.

those impeller blades take a curved set in "shape", but don't stick to the housing, and would never stick hard enough to get the belt to slip around the pulley.

doesn't matter, it's time to change them anyway!

Re: 496 sea water pump
 

Impeller was toast, housing is fine. Looks like I "flipped" a couple of blades. Merc mechanic says that can happen when its dry and you first crank the engine. I can see where pieces from an impeller can cause major head aches. Took about an hour to get if off and apart. The diagrams posted elsewhere aren't exact. Think I could do it in half an hour next time now that I know what need to happen.

Thanks for the advise :drink:

Re: 496 sea water pump
 

Makes one want to consider a crank mounted pump, no belt to steal HP and the impeller change takes about 10 minutes.

Phil

Re: 496 sea water pump
 

I added a t-fitting into the raw water intake to the SWP on my 496HOs. No more dry starting.

Re: 496 sea water pump
 

Good Idea. I think I'll do the t fitting also. My boat sits from October- November until April or May. Only would take a minute or two in the spring to make sure there is water in the pump.

Re: 496 sea water pump
 

Putting it back together took longer than taking it apart. The serpantine belt is behind the mounting bracket for the Whipple Kit. That took a liitle bit to do and a couple of extra hands! Running fine now. :)

Re: 496 sea water pump
 

word of warning on the 496 style pumps, if the housing is scored do not change the impeller unless it is bad, alot of times the new impeller will not pump due tp capitation because the new impeller is not shaped to the housing(thats the problem with the brass housing) if this happens the only cure is to replace the housing

Re: 496 sea water pump
 

Housing was in good shape. No scoring. Ran it this morning at the local lake and all looks good.

Even though it didn't draw water when I first started it, I back flushed from the top of the motor and from the out drive when the pump was disconnected. I got several bits and pieces of impeller from each direction. I'm glad this board is around to provide all the advice and tips for stuff like this!

Re: 496 sea water pump
 

Changed mine yesterday, top and back brass plates were slightly scored (really light scores). I figured it would not harm so I replaced the impeller. The old impeller was in good shape, it had only lost it's flexibility.

Are you saying that as soon as you see scores, no matter the degree it should be machined and brassed?

Here is a picture of the situation:

Re: 496 sea water pump
 

that may or may not cause it to cavitate 50 50 shot

Re: 496 sea water pump
 

Mmmm... I don't like 50/50 equations in boating... I'l call a machine shop tomorrow and see what they can do and how $$$ it would cost. I am also worrying about damage that could be done to the shaft assy by heat when soldering and planing the brass. A replacement pump costs 268$. At that price, I'd better just replace it.

I found different costs on the 496's Brass pumps depending on the engine serial number... The other model costs 500$ :eek: . The design seems a little different. What is the main difference or improvement over the 268$ pump?

Re: 496 sea water pump
 

There is a machine shop in Lake Havasu City, AZ that makes a shim kit for the scored brass housings. Contact Absolute Speed and Marine in LHC for the machine shop and kit..... The fix for the plate is to have it brazed and machined flat.

Re: 496 sea water pump
 

Do you know what type of metal the shim in the shim kit is made of? Shame they did not design this all out of stainless or plastic with replaceable stainless liners like the out board water pumps. Those are really durable.

Re: 496 sea water pump
 

Pretty sure its stainless....Might call Absolute Speed and Marine at 928 855 2252 to check on the detals.

Re: 496 sea water pump
 

My 03 496HO's, got their 1st impeller change this week, 143 hours, and every thing looked like new, replaced all just for GP. Normally this is an annual thing for me on my boats.
I skipped last year due to minimal run hours.

I always do my first start of the season IN THE WATER, not on a hose.
Now I have 2 emergency spares...
My 2 Cents.
Bryan

Re: 496 sea water pump
 

Been lurking for some time now and have received lots of helpful advice. So, thanks to all that have posted their efforts for the rest of us to gain from.
Anyway, just put a new impeller in too. loads of fun! I would think Merc could come up with a better design or easier access.
Question is:
Can you hook up a hose to the Bravo 1x to test run? it has the littlest pick up holes in the worst location.

Re: 496 sea water pump
 

Tape the low water pickup holes, and install standard ear muffs on the side water pickup...
For the 496's, my advice is to NOT run it on a hose... Get the boat to a ramp and test the engine there... The sea water system is a poor design on the 496's

Re: 496 sea water pump
 

It's hard to get good water pressure on just the hose. I put on the standard earmuffs, duct tape the lower pickup holes (don't forget to remove when your done) turn the hose up all the way. I hit the kill switch and crank the engine for several seconds (without starting) and then disengage the kill switch and start it up. I think this helps get the oil going a little, especially in the spring. I can tell that my exhaust risers are a bit warmer to the touch on the hose compared to when your on the water.

Re: 496 sea water pump
 

What was the condition of the pump parts. How many hours on the pump and what kind of water do you run in ie clear, muddy, beach on sandy shores, salt, etc.?

Re: 496 sea water pump
 

Splashed the boat Sunday, pump works great...