Rotax Water Pump

[Udi]

I have water coming off the bottom weephole of the body of the cooling water pump. The water is not leaking out, it's pouring out! It's a Rotax 532. I don't have all the radiator hoses connected yet, I just filled water into the block to see there are no leaks... Surprise...

Can anyone tell me what that means? I don't have a schematic of the pump.

Thanks

Udi-

[ToddP]

Udi,

I also have a 532. I've been told it has the "Water Pump Upgrade". Apparently there is a problem with the 532 water pump. I think that LEAF (Leading Edge Airfoils) might have the information on the upgrade.

Todd

[rehler]

"Weep hole" in the water pump housing? That might be the hole where a nipple is to go to be connected to the expansion tank with a small hose to let air bobbles out of the water pump housing. The water pump housing is full of water, so if there is a hole in it then water will come out.

[Udi]

I took the pump apart and investigated. The weepholes drain water from the space located between the two shaft seals. Water was coming out because one of the seals is bad. A new seal should solve this problem.

When will this madness end :confused:

Udi-

[mceagle]

Udi,
I hope the attachment works.
Pay attention which way the seal/s face. If you wish to replace the inner seal (oil) then you can drill a small hole in it then screw in a self tapper and pull it out. (Put a sleve on the bit so that it cannot go in too far and hit the bearing). If the engine is a later model it will have a spacer between the seals, but if not you will have to be careful how far you push the seal in - just flush with the outside edge. You can change this a couple of mil. each way if you have a worn shaft.
Hope some of this is useful to you.

[Udi]

You can change this a couple of mil. each way if you have a worn shaft.

Thanks, Tim!

This is very helpful. The shaft is indeed worn at the outer seal. Can I move the outer seal closer to the inner seal? I don't think I have a spacer in between the seals, it's an older model.

What is the purpose of washers 24, 25 and 26 in the picture? I don't have them. I only have 5 or 6 washers like 27 stacked together, and I have 28.

I think I'll just buy 2 new seals and all the washers in the picture. Is it hard to replace the seals?

Thanks!

Udi-

[mceagle]

24 = 0.5mm shim
25 = rubber washer
26 = supporting plate

Some of the earlier ones didn't have them. I would be guessing here but the shim places the seal the right amount in, the rubber washer holds tension on the shim and seal and the plate holds the lot from popping out. The plate is supposed to be used only once because it gets distorted removing it. The washers that you have stacked together must be used as shims to stop the impeller hitting the housing. They are supposed to run very close.
The outer seal can be installed deeper but not so deep as to block off the drain hole between the two seals. The drain hole was also done away with on later models so it probably wouldn't matter if you half covered it, as long as you did not expose it to the water on the pump side.
PS Don't forget to drain the oil before removing the oil seal.

[mceagle]

Udi,
Just found a copy of a later one and the diagram is identical except that parts 24 and 25 are not there. There obviously would be no problem leaving them out.
The seals are not very tight and are easy to replace.
No 54 is a smear of moly lubricant to be applied to the seal rubbing surface.

[Udi]

Thanks, Tim.

PS Don't forget to drain the oil before removing the oil seal.

There is no oil in my pump, and there are no nipples in the body of the pump. I guess that my pump is designed to run dry.

What's moly lubricant?

Udi-

[mceagle]

Udi,
The oil is behind the second seal - the centre of the crank has a gear to drive the rotary valve and the water pump and it is immersed in oil with a small plastic header tank mounted on the coil bracket.
Moly - molybdenum (spelling?) grease, a extreme pressure lubricant commonly used in CV joints in front wheel drives.

[Udi]

Tim,

I talked with a LEAF technician today and found that my water pump is an aftermarket pump that was designed to solve a problem the 532s had with their water pump. You can read about it here:

http://www.800-airwolf.com/pdffiles/ARTICLES/part%2050.PDF

You can see my pump pictured in this article. I am going to replace the leaking seal, move it back hoping that it will see a better shaft surface, and fill the volume in between the seals, and between the seals and engine with Dow Corning 111 grease sealant. I got this idea from Brian at LEAF. Hope it works. If it doesn't work, I will have to replace the whole shaft... :(

Thanks,

Udi

[Chuck Roberg]

This is from a Lockwood Aviation Ad in SportPilot.

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