Challenge: Water Pump

[Charlie]

This is a made up water pump scenario.

Remote town in a third world country with no metal shop. Your engine oil is now grey. Tracked it down to a leak in the water pump seal. Oil on one side of the seal water on the other. By chance you have a new seal. Get it all taken apart and find that the shaft is scored in the area where the seal sits.

One of the tools on board is a small drill press. Took the shaft and spun it at a slow speed with 80 grit up to 600 grit sand paper. Got rid of the score but the shaft is now 11.95mm instead of 12.01 (Approximation .004"). Buying a new shaft won't be easy to obtain.

Seal fits loosely. Not sure how tight it is supposed to be.

Do you?

1) Take some JB weld rough up the shaft so the JB weld will adhere and work the shaft back into round?

2) Use some random goop to seal the "seal" and cross your fingers? If so what kind of goop?

3) Solder a bit of silver solder and then work the shaft back into round?

4) Use the seal and cross your fingers?

Other ideas? Comments?

[s/v Jedi]

Originally Posted by Charlie

This is a made up water pump scenario.

Other ideas? Comments?

I would disconnect the water circuits from the pump, remove impeller, close it up and rig an electric pump until I can get a new pump, after which I would have the broken pump rebuilt.

[Charlie]

Jedi:

I guess that that would be possible. Lets's say that in this situation the shaft did need to be repaired (I'm actually in this situation with my son's dirt bike but the new shaft is more then my son has to spend -- but he did have enough to spend his last $50 on some stickers! B/c of that I won't lend him the money to buy the new shaft. Dad is being a hard a$$.)

I was thinking of putting a couple of "O" rings on the shaft under the seal.

[44'cruisingcat]

I'd change the oil, and use the other engine, only using the faulty one when neccessary for maneouvering.

[boden36]

I would try removing the spring from inside the seal, and either using a shorter spring, or replacing the spring with a suitably sized O ring which will squeeze the seal tighter. You could resize an O ring by cutting a segment out and rejoining with super glue if necessary.

Regards,
Richard.

[Charlie]

Thanks Richard that is a great idea.

[model 10]

Just don't press the seal in all the way, simple.

[dannobee]

There are a couple of different ways to fix this.

One fix is to not drive the seal in all the way. Seal now rides on a "new" surface. The seal might pop out from cooling system pressure or crankcase pressure. You'd probably worry about it popping out at the worst possible moment.

Permanent fix(es) that I can think of. 1. Since you have a small drill press, you "might" have a small welder. Weld up the shaft, then chuck it up in the drill press and dress it down using files. When it gets close to the correct size, clean up with your sandpaper until smooth. 2. Carefully remove the garter spring (it's the spring putting tension on the seal.) These garter springs almost always use a "nib joint" that fits inside the spring to form a circle. Find the joint and "unscrew" the garter spring. Look carefully for the part that fits INSIDE the other part. You want to trim off a few coils off of the OTHER side, then screw the garter spring back together. It'll now have more tension to seal against the worn shaft.

Order/obtain a replacement shaft and seal to have as spares, although 0.004" isn't a big enough deal to worry about and the seal would likely seal just fine, but you get the point.

[Jim Cate]

Charlie, first, if the shaft is but .004" undersize it will likely seal just fine. The o-ring trick will also work... IMO, one should always replace the spring with an o-ring. This is standard practice most places for salt water pump seals.

But finally, the long term fix is to buy a thing sold under many trade names, ones like "Speedy Seal" and the like. This consists of a very thin sleeve of stainless that you simply slip over the shaft in way of the seal. Gives the seal a new, round, shiny surface to work on... a standard thing in most bearing shops and commonly used in industrial applications.

Cheers,

Jim

[daddle]

Originally Posted by Charlie

Remote town in a third world country with no metal shop.

I challenge that statement. Remote towns in third world countries are far more likely to have a machine shop than a small town in the first world. I'd spend some time hunting down a shop. Maybe weld and turn the shaft. Or have a new one made.

I handed busted water pump pulley to a taxi driver in Sandakan Borneo, had a machined replacement in 2 hours. About $10. Try that in, say, Santa Barbara.

[never monday]

put an oring between the two seals if there is room. This will aid in flinging off any water that is transient on the shaft.

[Charlie]

@Guy thanks that would work but in this case (son's dirtbike) the seal takes up the entire space of the shaft.
@Dannobee I thought about using a welder but the impeller is on the shaft and made of plastic. They want $25 for the impeller and $45 for the shaft plus tax and shipping so we are close to $100. Thanks for the info on the spring I will see if I can adjust it tighter. I think that will work.
@Jim Thanks for the info on Speedi Seal I found them on line but they are almost as expensive as a new shaft. I could see using them on a bigger shaft or if I had to pay labor but in this case too costly to justify. The O ring trick sounds good I will give that a try and see if it tightens the seal.
@Daddle thanx.

[125Miles]

This is what I did on westerbeke water pump. There was plenty of space at the ends of the shaft that could move it to one side or another for may by 1mm so seal would be seating on the new surface. Good as new for another 500hours. If there is not enough space I would grind off one side of the shaft and put shim /washer on the other to limit the end play a bit, if needed.

[Charlie]

Here is what I ended up doing. I took the shaft and put it in my drill press. From there I wrapped a piece of emory cloth around the shaft. I was able to get rid of most of the sharply scored part of the shaft. When I dragged my fingernail across I could still feel some sharp areas. I took a dremmel type tool and put a polishing bit in it. From there I was able to use a buffing compound to polish the scored surface so that it had a soft edge. I then moved the seated location of the seal by about 1mm (which is all of the room I had). I replaced the springs with "O" rings. The 13mm "O" rings were not tight enough so I used 7/16" rings. I'll let you know how it goes.