How to Replace Your Pool Vac Ultra Gearbox

If you’ve got an older Hayward Pool Vac Ultra that stalls at the edges of your pool, but otherwise seems to running fine – it’s drawing water and the wings are flapping -chances are high the gearbox has gone south.

The gearbox periodically turns your Pool Vac so that it covers the whole pool floor rather than clear a swath and then stop.

This repair only takes about fifteen minutes, requires only a replacement gearbox and a Phillips screwdriver, and costs about fifteen bucks. You can order the gearbox from pool parts supply houses and have it in just a couple of days.

Loosen the screw from the access plate in the center until it’s free. The access plate fits snugly in place, so you’ll need a little force to get it loose.

Remove the four(4) short screws that hold the chassis in place. Two of them are a little awkward, as they’re under the spring-loaded front flap. The chassis will come off as a unit.

Remove the four(4) screws that hold the bumper assembly in place. The bumper’s slightly press-fit around the lower middle body, so it may take a little pressure to remove it.

Lift out the turbine and it’s set of bearings, and set them aside.

Two(2) more screws hold the lower middle body against the upper middle body. Remove those screws, and lift the lower middle body away from the remains of the Pool Vac.

The gearbox assembly rests on top of the medium turbine. You may see an orange disk resting on the medium turbine, or you may see no disk, or you may see the whole gearbox assembly. It all depends on the condition of your Pool Vac. You will certainly see the grind circle left on the turbine by the orange disk. There’s a big hint in the orange circle.

The gearbox slowly turns all the time the Pool Vac is running. The orange disk, on the gearbox shaft, slow turns with it. When the cutout in the disk passes over one of the holes in the middle turbine, the entire Pool Vac latches onto the disk and rotates with it. When the cutout moves past the hole, the pressure on the orange disk releases, and the Pool Vac continues on in a straight line. When the gears get tired, the orange disk no longer rotates.

So, remove the tired old gearbox, including the orange disk and white nylon washer with the square hole in the middle. You can drop those into the recycling bin.

Flip the lower middle body over, so that the rear screen points up.

Fit the new gearbox into the raised outlines on the middle body. The little alignment post on the gearbox goes to the rear of the Pool Vac, and the orange gear and little white washer rest on top.

Lift the remaining Pool Vac assembly – the part that has the middle turbine on it – and fit it firmly over the middle body. It takes a little manipulation, but it will snap firmly into place, trapping the orange gear in the correct position.

Turn the entire assembly over again so that you can start the reassembly.

Replace the two screws that hold the middle body in place. Tighten these down snugly, but not too tightly. If you turn them too hard, you can crack the plastic middle body. But, if they are too loose, the orange disk will be too far from the holes in the middle turbine to build up any pressure.

Set the turbine bearings into the cradles on either side of the hole – they’ll only fit one way – and make sure the turbine spins freely.

Snap the bumper assembly into place over the middle body and replace the four screws.

Snap the chassis into place over the bumper assembly and replace those four screws. Remember that two are under the front flap.

Replace the access plate and tighten down that screw. You’re done! Congratulations!

Please note: do not do this procedure if you are not certain that you can complete it safely, or if it doesn’t seem accurate. Skippity Whistles provides this information as advice, and cannot accept any liability for your usage of it.


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Published by John D Reinhart

Author, technical writer, videographer, actor, and naval historian John D Reinhart is a very busy guy. You can find his novels as

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