Darley P-100 Water Pump - Corrosion

[uniquify]

I bought this water pump in unknown condition. When I finally received it, I found it was seized up. There was a lot of corrosion on the impeller that was visible by removing the cap from the inlet port. I'm guessing it was used with salt water and put away wet.

The tag on the pump is hard to read, but a quick search on Darley's website gives Model#: 2BE10YDN and NSN: 4320-01-387-2869.

I wasn't sure if the seize was rooted in the pump or in the engine, but figured the visible corrosion in the pump was a decent starting point. Besides, if the engine had problems, I'd need to take the pump off any way.

Before digging in:


Visible corrosion in the pump:


The main pump housing came off pretty easy. Removed the nuts, gave it a few taps with the rubber mallet and it came right off.



The impeller took a lot more persuasion, but eventually came loose with a combination of PB Blaster, heat, 3 pry bars, and a 3-jaw puller. After "gently" prying for way too long, I finally got smarter and tipped it over so the impeller was facing up, and soaked it with PB Blaster until I could see it wicking into the keyway. Eventually, I got the impeller to come off about a 1/4", which was just enough to get the 3-jaw puller behind it. Unfortunately, I munched the inboard head a little with the first small prybar. That doesn't appear to be a sealing surface, so if all goes well, I'll try to touch that up with a file.

 

[uniquify]

On the bright side, once the impeller came loose, the engine (Yanmar L100) freely turned. The air and oil filters looked good, compression felt good, so I added fresh oil and a little fuel, then primed it 10 pulls while holding the decompression lever. After that the engine started on the first pull and seemed to run great.

 

[uniquify]

So, what's the best way to deal with this corrosion?



Guessing that might vary a bit based on materials. According to the manual there's a bit of a variety:

Part	Material
Pump body	AL 319
Inboard head	AL 319
Impeller	BRONZE 85-5-5-5
Strainer	360 BRASS
Drain valve	360 BRASS
Impeller shaft	316 STAINLESS STEEL

I'm thinking about using a soft bristled brush. Maybe brass or nylon?

Any recommendations on a cleaning agent? Vinegar?

 

[GopherHill]

Try some vinegar. Keep an eye on things not to get carried away. If badly pitted, mix up some marine epoxy and do a good smoothing job to minimize turbulence. Are you going to use it as a fire pump? Parts seem to be readily available.

 

[uniquify]

Try some vinegar. Keep an eye on things not to get carried away. If badly pitted, mix up some marine epoxy and do a good smoothing job to minimize turbulence. Are you going to use it as a fire pump? Parts seem to be readily available.

Thanks for the advice. I'll start with vinegar and see how that goes.

My goal is to fit it onto a 500 gallon water wagon that the in-laws can use to haul water to cattle and maybe help put down the occasional brush fire. It's probably overkill for that, but we'll see how it goes. There was a fire about a month ago that was too close for comfort.

 

[G744]

I'd have all the internal pump parts bead blasted.

DG

 

[SCSG-G4]

I'd have all the internal pump parts bead blasted.

DG

Bead blast then marine epoxy to smooth out any pits.

 

[GopherHill]

Bead blast then marine epoxy to smooth out any pits.

Good idea. I don't have access to a bead blaster so I didn't think of that.

 

[uniquify]

I picked up a cheap blaster and hit the pump housing with some glass beads.

Not perfect, but better than it was:


There were some areas that were pitted from corrosion. I filled the pits and smoothed things over with marine epoxy. After it hardened, i gave it a quick sanding with some 120 and 240 sand paper. While I was in there I knocked down a high spot in the casting behind one of the mounting studs.


Also the 1/4 NPT drain valve was corroded shut and stuck fast to the housing. I couldn't get it to budge with a big wrench or heat. So I ended up drilling out the valve and tapping for a new 3/8 NPT valve.

Got the pump put back together then ran out of daylight. Hope to give it a run this weekend after I work out a way to mount it on the water trailer. Wouldn't be surprised if it needs a seal kit, but I want to see it move water before investing too much more in it.

 

[GopherHill]

Good job on that. Even if the seal leaks, it should be good for your purpose.

 

[uniquify]

The pump has been installed on the trailer and will move water. It'll empty (or fill) the 500 gallon tank in about 5 minutes.

The cattle enjoy some fresh cold water on the hot still days when there isn't enough wind to turn the windmills.

Here are a few pictures at the end of a successful project.