Leaking GT-40 water pump

[peteSki]

I recently replaced the impeller, o-ring and gasket on the raw water pump on my 98 Ski with GT-40. I ran the boat on the trailer to test for leaks and noticed that the pump has a small drip leak. It did this before I changed the impeller, but on a previous impeller change I didn't have the proper gasket and made my own, so I thought it was from my home made gasket. This time I assumed since I had all the correct parts that the leak would be gone, but it has not. On closer inspection, I can see that it doesn't appear to be the gasket at all, as it's coming out of the pump shaft.

I borrowed a pic from another post to show exactly where the water is coming from, it is marked as "B".

I pulled the pump apart twice to be sure that the o-ring hadn't slipped out of the groove or there was any old gasket there, all checked out OK. Since water is coming out of the pump shaft, seems to me that water is leaking out between the impeller and the spacer plate, then out the holes in the pump shaft.

While the leak is only a drip , is this an indication that I should replace the spacer plate or the pump itself? As best I can tell the impeller itself makes the seal so water doesn't escape through the hole in the spacer plate into the shaft side of the pump.

Would appreciate any suggestions or similar experiences.

Pete

[DanielC]

RE: Leaking GT-40 water pump

How smooth is the brass plate between the impeller housing and the bearing support casting? You might try to polish any grooves out of it. If the grooves are too deep on one side, polish it, on the other side.
To polish the plate, start with 320 to 400 grit wet sandpaper, on something flat. Go to finer grits of sand paper, as the grooves get polished out.

[DanielC]

Water Pump, GT-40 more info

Just to avoid any confusion between American English, and Australian English, I believe what I call a brass plate, you call a spacer plate.
How many hours are on the engine in the boat? If it is getting close to about a 1000 hours it might be necessary to replace the raw water pump. Check inside the impeller housing for excessive wear, look at the cam that squishes the impeller between the inlet and outlet ports.
With the raw water pump disassembled, does the pulley turn, with a very slight drag, and no free play or slop in any direction? Listen as you turn the pulley, there should be no noise coming from the bearings. It is normal for there to be a slight drag. Not much, but a little bit.
One thing I have learned is it is not necessary to get the raw water pump belt as tight as the alternator belt on a GT-40. Tightening the belt too much will put a lot of stress on the raw water pump bearings, and they will wear out sooner. It is OK if the same pressure put on the water pump belt causes it to deflect a few mm farther than the alternator belt deflects.

[peteSki]

Thanks for the suggestions. I will take another look at the brass plate as I did notice it had quite a bit of markings on the impeller side, but didn't really inspect it closely to see if those were grooves or not. I really just gave it a wipe down and then reinstalled it.

The boat has just over 1000 hours on it but I believe the raw water pump is in good condition because:

• there is no play in the bearings when spinning the pump when it's off the boat
  it is easy to turn, only a slight amount of resistance
  turns smoothly, no noise or vibration

Since it's raining again today and we won't be on the water, I'll pull the pump again and give the brass plate a closer look and sand it down as suggested.

Pete

[AirTool]

Since it's raining again today and we won't be on the water, I'll pull the pump again and give the brass plate a closer look and sand it down as suggested.

Pete

As you change sandpaper from coarser to finer, be sure to rinse the brass plate and the wet/dry sandpaper to keep from contaminating the fine paper with residual coarse grit.

[peteSki]

I pulled the pump again and took a close look at the brass plate, it had quite a bit of grooves and wear on the impeller side. I started to sand it down and then had a thought that if I put it on backwards, the other side was in pristine condition with no grooves at all. So I cleaned it up and installed it. Funny enough I still get a drip leak, and as best I can tell it seems to be coming out near the lower mounting bolt.... it drips at idle and then gets less with RPM. Not going to worry too much about it now, but will consider a pump rebuild or replacement in 6 months (our winter).

A couple pics showing the pump components with the brass plate grooved side and then the other side which is now installed on the impeller side.

Pete

[jaybird]

Water Pump

Its the seal and bearing not the brass plate. Been there, done that! You need a complete rebuild kit with the shaft seal and bearing.

[jaybird]

Pump rebuild kits

You can find parts and instructions here:

http://www.sherwoodpumps.com/FileAtt...22_ENGLISH.pdf

[DanielC]

The only thing that prevents water from going into the bearings on the shaft housing is the impeller riding against the brass plate. The hole in the brass plate is much bigger than the shaft that turns the impeller. The bearing on the impeller end of the shaft housing does not close the hole in the plate.
The pump was designed to accommodate a slight leak, that is why there are holes in the shaft housing.
I would try a new impeller on a smooth brass plate before I condemn the whole raw water pump.

[jaybird]

Leak

Daniel,
Respect your opinion, you have been a great help to me in the past. Unless the subject pump design is different; the seep holes where the pump is leaking are to allow the leaking water to escape without damaging the two main shaft bearings (19) and to give an indication of a bad seal; the ceramic seal (14) is to prevent any leak. A perfect fit between the impeller and brass plate is difficult to maintain. If a good seal is in place the pump will not leak at the holes indicated even with poor contact between the brass plate and impeller. The bearings (19) are probably fine but if the shaft seal has failed its a good time to rebuilt the pump with new bearings and seals.

Had the same problem and had to rebuilt one a few years back.

[DanielC]

RE: Leak

How was the pump rebuilt? I have another pump that might be a good candidate for rebuilding, to make it usable again.

[jaybird]

Pump Rebuild

Fringe benefit, I run a machine shop. :grin:
All you really need is a small press, various tools, snap ring pliers and the correct parts. If you don’t consider your time it’s really quite cheap unless the cast housing is badly pitted and/or the shaft is excessively worn.
I have not priced the parts recently, so not sure the total cost of the rebuild kit. I cheated and just got the shaft seal from Sherwood. I had a local bearing supply house match the bearings and other parts (Bearings & Drives).

[hyparks]

Old thread I know but been on water today and my pumps leaking from the weep holes. Took it apart and mine has a spring inside with a type of seal on the end. Searching the site etc and other peoples rebuilds show no spring? Anyone have an insight into this? My boat is 01 super air gt40. Thanks

And does anyone know what the bearing numbers are for the pump?

Thanks

[hyparks]

Anyone know which repair kit I need? Do I need to buy the spring part seperately? Thanks