Thread: servicing Davey pumps and the like

ok I'll pull it apart tomorrow - take it from there
thanks

Used to work for a Davey/Grundfos agent repairing pumps. Of course all pumps are different, but I do have some general tips for repairing/servicing pumps.

Make sure all body seal surfaces are spotless before reinstalling o-rings and rubber seals.

Smear a light coat of silicon grease or vaseline on all rubber seals but make sure you don't get any on the ceramic wear-surface of the mechanical seal.

Rusted shafts at the mechanical seal, and rusted bearing housings, need to be replaced. Rusted motor housings (usually at the pump end) are usually the end of the pump.

On smaller pumps, the impeller screws on to the shaft with a normal right-hand thread. (something apprentices seem to get wrong a lot)

If impellers have a lot of mineral build-up on them, it can be removed by immersing in a weak acid solution overnight. (1 litre of diggers hydrochloric acid in a bucket of water) Alloy impellers are very rare, but if you have one, then don't try this method.

Seized bolts in alloy housings can sometimes be freed with a short, intense burst of heat from an oxy torch on the housing while keeping pressure on the bolt.

Don't forget the wave washer behind the fan-end bearing when you re-assemble. Fans usually can be levered off using two large screwdrivers. Watch for circlips or grubscrews that need to be undone first.

Use pullers to get bearings off, use a small length of pipe that just fits over the shaft to tap bearings back on. (presuming you don't have access to a press)

That's all I can think of for now. Hope I've been some help.

i know the bearings are all standard sizes , ive bought a few for a mate who cant get them where he lives.

thanks Onefella!
if the electric motor is noisy/having a bearings issue I won't try to rebuild it
if its at the pump end, I'm going to give it a shot

the noise is at the electric motor end, could be a bearing
I'm having trouble with the impeller I can't get it off the electric motor axle
there is no nut to remove, only a threaded screw that spins on the rear of the motor but nothing at the pump end
I'm not sure if I'm supposed to lever the plastic impeller off the axle (and is there is a nut underneath) or whether I'm supposed to undo the screw at the back - I can't seem to do either !
I've tried the screw (left and right handed thread) no movement
I've tried leavering off the impeller but I don't want to damage it

any ideas?