Raw Water Pump

Leaking out the weep holes and corroded.

Completed 04/05/2020
Removed, refurbished and reinstalled.

Remove the pump.
1. Close the raw water thru-hull.
2. Remove the hoses from the pump.
  1. I had to use a propane torch to soften the rubber, then popped the seal by carefully inserting a flathead screwdriver.
3. Remove the 4 bolts mounting bolts
  1. Mine were very rusted, but were surprisingly easy to remove! Thanks for using anti-seize, Mr. Previous Owner!
4. Clean the area thoroughly, and without dropping any old gasket material or gunk into the engine, carefully remove the old pump.
5. Carefully scrape the old gasket material from the engine. I used a paint scraper, PB Blaster and a rag.
Disassemble the pump:
1. Remove the impeller:
  1. This was the hardest part of the whole job! Those 4 impeller plate screws were frozen hard and made of soft bronze.
  2. I chipped away at the rust with a screwdriver, soaked in PB Blaster, cleaned and chipped and still no go!
  3. I then soaked the pump with the impeller cover plate submerged in coke overnight. The next morning, cleaned, PB Blaster, cleaned, tapped lightly with a hammer, PB Blaster, scraped a sharper groove for the screwdriver and FINALLY got the screw driver to turn a screw! Be careful, these screws are very easy to strip.
  4. One more night of soaking in PB Blaster and I got the rest of the screws out the next morning. Definitely need to replace these old screws.
  5. Once the cover plate was off, the small impeller puller worked nicely to pull out the old impeller. Still in decent shape after over 4 years of use!
  6. Don’t drop the key as you pull the impeller. Mine was stuck pretty well, but a couple soft taps of the hammer on a screwdriver got it right out.
2. Pull out the shaft and shaft bearings:
  1. Use a large puller to pull out the shaft. The impeller puller is too small. I’ve heard some people use a block of wood and a hammer with good results, but my puller was immediately available and easy to use without fear of damage.
  2. One of the shaft bearings was really rusted and frozen on tight. I tried the large puller with not a budge. Soaked it in PB Blaster for a few hours, chipped away at the rust, pulled, soaked, cleaned and chipped for a day with no results. Oh well, I’ll just use the spare shaft I had ready.
  3. I’ve heard some people just cut out the old bearings being careful not to damage the shaft. Or use a machine press…
3. Tap out the water seal:
  1. The water seal is rubber, enclosed by a metal cap. Make sure they both come out. The rubber came out easily, then I had to use a perfectly sized socket and hammer to gently tap the metal cap out against the rust. It’s very easy to scratch the bronze pump body here, so I wouldn’t use a screwdriver.
4. Clean and paint the pump body:
  1. I used a screwdriver and PB Blaster to scrape out the rust. But that bronze is soft! Don’t use a hammer and screwdriver or you will score the pump. I made that mistake, but luckily it didn’t score anything that needs to seal. The rubber impeller won’t know the difference :)
  2. Two of the weep holes were rusted shut. I use a nail and hammer to free up and clean those.
  3. And finally, I used a wire brush dremel fitting to clean off the old paint, rust and gunk until it was mostly shiny bronze.
  4. Tape and razor blade the excess off in preparation to paint. Also plug the holes with tissue or paper towel to keep those clear.
  5. I used Rust-oleum Engine Enamel. (No need for high temp, but I use that for everything on the engine). 2 coats should do the trick.
Reassemble the pump:
1. First press the two bearings onto the shaft.
  1. Mine was pre-assembled, but the easy way is to use a machine press. Or look online for home-made presses using C-clamps, a vise or wood and a hammer.
2. Next press the shaft into the pump body.
  1. This was easier than I thought. I just placed the pump onto some wood to protect against scratches, balanced the shaft over the hole, used another block of wood on top and gently banged it in with a hammer. No problem.
  2. Note: The top bearing will not be completely flush with the pump. A millimeter or 2 will remain above the lip. Just check that the bottom one is fully seated against the pump.
3. And finally, tap in the new water seal.
  1. I found a socket that had the perfect circumference to fit over the shaft, but it was slightly too short to reach the water seal. $1.29 and a drive to the hardware store and I had the perfectly size nut to act as a spacer to bang against.
  2. A few light taps and it was perfectly seating with no dings.
4. Install the new impeller:
  1. Press the key in by hand, angling it so the lowest point faces you. This allows the impeller to slide over it, pressing it deeper as it fully seats.
  2. Squish the impeller in while aligning the slot with the key. Don’t worry about aligning the arms in any particular order; They will flop right over before you even take your hand off the starter.
  3. To lube or not?
    1. If you do, make sure to use glycerin impeller lube. Petroleum based lube can cause the impeller to eventually disintegrate, throwing pieced of rubber through your system and most likely clogging your heat exchanger.
    2. I didn’t lube, because my impeller is very close to the raw water intake. It will suck in water before it overheats.
  4. Place the gasket onto the pump body.
    1. Using a very thin film of gasket maker on both sides of the paper gasket will make it easier to align and delay leaks in the future. As one guy online said, “These paper gaskets suck balls.” But don’t use anything thicker than the paper gasket. The clearance between the cover plate and the rubber impeller is important.
  5. Install the cover plate and screws. Make sure to use anti-seize on those screws! That seriously saved my butt during the removal process after years of rusting and corroding.
  6. Paint the cover plate to prevent future corrosion. After mostly drying, I uscrewed and screwed the 4 screwed just to break the paint seal for ease of removal later.
Install the pump onto the engine and test:
1. Stick on the fiber mounting gasket with a film of gasket maker on both sides.
2. Install the 4 bolts with anti-seize.
3. Reinstall the raw water hoses. Now would be a good time to add 2 new hose clamps to both the in and out hoses.
4. Run the engine and check for water out the exhaust and leaks at the pump.
Problems:
1. If no water after 10 seconds, stop the engine and feel the impeller cover for heat. Don’t run that thing dry or it will melt.
2. If you are getting water, let the engine run for 10 minutes or so while checking for leaks and checking the engine temperature.
3. If you are getting leaks out of the weep holes, something isn’t right. They should be perfectly dry. One of the purposes of those weep holes is to warn you that a bearing is going. Kind of like brake wear indicators. One bearing can fail as a warning, but then there is only one bearing left before water enters the engine causing major damage and a potential engine rebuild.