Pitting discovered under Impeller Housing - Any Advice

[AMMO DAWG]

I have been restoring my 2006 Searay 185 and stated disassembling the lower unit (Alpha 1 Gen II) to replace the seals, impeller and to do some painting. The impeller housing was pretty caked up with white corrosion and after pulling it off and cleaning up the mounting surface I found some pitting. Looking for some advice on how to deal with it an how typical this is. Thoughts I had were some JB Weld, Marine Tex, gasket sealer etc. Appreciate any advice, I attached some pictures of the pitting.

 

[harringtondav]

That is significant erosion. The surface pitting can be leveled with epoxy. My concern is the erosion around the edges of the water inlet cavity. It looks like there is barely enough surface to seal the pump gasket and face plate.

Set your face plate in position and scribe its outline with a sharpie. I'd like to see 3/16", 4-5 mm of solid surface to be sure of a good seal.

The only reliable way I know to build up that edge is to have a prop shop weld it up. Then file or carefully belt sand it back flat with the rest of the surface. That will be messy, and a bit iffy. Keep the seal carrier in place until you get it figured out. It well help keep contamination out of the lower gears.

PS - Edit. Be sure all of your anodes and continuity cables are in place and secure. It looks like something isn't working.

 

[Bt Doctur]

You could clean it thoroughly and apply fiberglass resin , sand and paint

 

[Rick Stephens]

I'm not sure that location needs a whole lot beyond maybe using some perfect seal between the gasket and the pitted surface. It doesn't have to be perfect. Water on both sides.

 

[dingbat]

JBWeld and a flat file to level the surface.

The trick is cleaning the surface clean before applying JB. Lacquer thinner and a tooth brush sized wire brush are you friends

Good enough to seal a head gasket. Good enough to seal a water pump base

 

[Bondo]

The trick is cleaning the surface clean before applying JB. Lacquer thinner and a tooth brush sized wire brush are you friends

Ayuh,.... A ssteel or brass wire brush,......

It doesn't have to be perfect. Water on both sides.

It's gotta be Air tight pumpin' on plane,.......

 

[Rick Stephens]

It's gotta be Air tight pumpin' on plane,.......

I'm gonna call baloney on that. Alpha water pumps are vented to prime. A little pitting, resolved with a little sealer, isn't going to change that they aren't sealed up anyway.

 

[harringtondav]

You got me thinking on that, Rick Stephens . At some rpm I suspect the housing cavity above the water pump is mostly filled with exhaust....assuming through prop exhaust. A leak path under the pump's face plate could be the path of least resistance for the pump inlet. I'd think once the water pump starts drawing air and cavitating, it's water output would drop like a rock.

That's why I worry about the corrosion/erosion on the starboard side of the OP's pump inlet cavity edge. ...don't know if the plate & gasket have a enough sealing surface.

 

[Rick Stephens]

Personally, I'd coat it with perfect seal, drop a gasket on it and go boating. That's me though. Not like I have fixed hundreds of the things like Bondo has.

 

[harringtondav]

Personally, I'd coat it with perfect seal, drop a gasket on it and go boating.

I'd go with that. The proof of the pudding is in the engine cooling. If OK, call it a win. If not, a re-do is one of the simplest out drive tear downs.

 

[achris]

You got me thinking on that, Rick Stephens . At some rpm I suspect the housing cavity above the water pump is mostly filled with exhaust....assuming through prop exhaust. A leak path under the pump's face plate could be the path of least resistance for the pump inlet. I'd think once the water pump starts drawing air and cavitating, it's water output would drop like a rock.

That's why I worry about the corrosion/erosion on the starboard side of the OP's pump inlet cavity edge. ...don't know if the plate & gasket have a enough sealing surface.

You're all missing the fact that as the boat goes forward, water is being forced up to the 'suction' side of the pump (through the water intakes below the pump). THAT would be your 'path of least resistance'. Merc supply a thin METAL gasket between the face plate and the housing now, so I don't think they are concerned about getting a nice seal on that surface....

To the OP... If you're concerned about it you can, get it welded, then machine is nice and smooth and paint it so it doesn't happen again, OR, fill it with fibreglass resin or JB Weld, file it smooth, and paint it.

Personally, I'd just prep the surface for painting, paint it and throw it all back together, it's not a problem.
(See the theme here? PAINT IT!)

Chris...........

 

[AMMO DAWG]

Thanks to you all, I'll let everyone know how it turns out, again thanks!

 

[JoLin]

Personally, I'd coat it with perfect seal, drop a gasket on it and go boating. That's me though. Not like I have fixed hundreds of the things like Bondo has.

Both my drives (27 years old) have a good amount of pitting around the impeller housing. I do what Rick suggested. No cooling issues whatsoever. If it makes the OP feel better to fill the voids, he should do it. It certainly won't harm anything.

My .02

 

[AMMO DAWG]

Thanks John, just what I was looking for!