1998 225 Optimax Water pump / cooling nightmare

[flycaster1]

  I just dropped my lower unit today getting ready for the 2015 season and planned on freshening up the water pump. To my dismay there is some serious damage to the lower unit in the area where there is a separation between the exhaust cavity and the water intake cavity. because of the fact there is a bleed hole on the water pump plate to aid in priming of the pump I would guess it allows water to settle there when the motor is tilted up and has rotted its way right through thus opening up a gap where water pressure which is supposed to be going up to the powerhead is being reduced as some of it is dumping into the exhaust cavity.  Any help with this would be greatly appreciated. I am thinking of having it welded up and repaired but wonder if its even possible.????  Thanks in advance.

[fitz73222]

Are you saying that the casting is split apart between the exhaust cavity and the water intake cavity or are you saying that the water pump base is split at that weep hole because that can be replaced. A picture would be great.

[Aaron43]

Picture?

[Capt. Bob]

Picture?

How about a "selfie" with the lower unit casing?

[flycaster1]

Finally got a couple sized down.
Here's one.

[flycaster1]

And another ....

[flycaster1]

Here's a third.

[fitz73222]

Well Fly,
I've never seen one that corroded. Is it corrosion or freeze damage that just blew out the casting. Weird. It is a non critical area structurally speaking. So I would first clean it throughly, possibly build a cardboard berm if you will and inject some kind of 2 part epoxy or polyester compound and make a new levee. You may have one heck of a time getting clean enough to even think about welding it, thats some dirty aluminum imbeded with exhaust oil and salt. I'll look at a gearcase I have tonight and try to visualize a repair.

[fitz73222]

Fly,
I've looked at the gearcase I have in stock but it is a different design, not from a 3 liter. I looked at assembly views of your gearcase. All that casting does is separate the exhaust from the water chamber. Short of replacing the case here's what I would do. Remove the filler block. grind out the rotten aluminum. Take the filler block and drill two holes through the block to allow attachment of a 1/4-3/8 thick aluminum plate that is fitted to fill the corrosion void, also drilled to match the filler block and filed flush to support the water plate. bolt the plate to the filler block and make a drop in insert to replace the corrosion void. You may have to shim the gap between the filler block and new plate. Fill the voids with silicone. On models with the standard water pump base, that bridge area was filled with silicone brand new from the factory so this isn't some shade tree repair, Mercury did  it too and it worked! This is going to take a lot of dremel and filing work but this should not be a problem.

[GoneFission]

This looks like it might be a good application for Alumiweld.  It's basically a low melting point aluminum solder/braze.  Brush or grind the area out, use a propane torch to fill it in with the Alumiweld material, and then grind to shape.  This seems like a place where it would work well.  Check out the use and video at: http://www.alumiweld.com     

[baby1]

 wee all know JP weld as well

[Aaron43]

Try some Marine Tex. Its a 2 part epoxy, sandable, drillable....clean up the rot, tape some cardboard inside the exhaust side build up the marine tex where the metal is missing, let it dry then remove the cardboard and tape, sand the top flat and paint it...

[Aaron43]

This may be an option for u....http://www.sterndrive.cc/product/Mercury-90-216.html

[fitz73222]

This may be an option for u....http://www.sterndrive.cc/product/Mercury-90-216.html

Hi Aaron,
Do you guy's use SEI gearcases as lower cost replacements? Asian manufactured but so is half of Mercury's line these days. Great warranty though. I was wondering if any of the commercial guys are running them in your neck of the woods? Great price but wanted to know if you are just getting what you pay for.

[Aswaff400]

This may be an option for u....http://www.sterndrive.cc/product/Mercury-90-216.html

Hi Aaron,
Do you guy's use SEI gearcases as lower cost replacements? Asian manufactured but so is half of Mercury's line these days. Great warranty though. I was wondering if any of the commercial guys are running them in your neck of the woods? Great price but wanted to know if you are just getting what you pay for.

i know the mechanics in my marina offer SEI drives and lowers as an option to our customers. most opt for the SEI unless insurance is paying for it... we've had pretty great results from them. hell the lower on my 225EFI is an SEI lower.