Yanmar ysm8 impeller: speed seal or new pump?

[barnaclephill]

My impeller is about 10 years old, still going strong and looking good. Changed it for a new one, precautionary, but the new one didn't pump anywhere like as much water as the old. Engine began to overheat. Tried this a few times yesterday. Gave up and put the old one back in.

The cover plate on the impeller/pump has a worn groove, perhaps a millimetre thick, so it's raised in the centre, and worn on the edges where the rubber things (arms?) rub against it.

Will a Speed Seal cover plate solve the problem, as it has a raised o-ring, or will a whole new water pump be the solution? I know it'd be pricey, but better than keeping the old impeller. Or should I carefully file flat the cover plate or the new impeller even?
Whatever, I changed the screws, whose heads were wearing, for new screw/bolt heads to make taking off the cover much easier.

[neale]

Can you turn the cover plate around? You can on some pumps.

[barnaclephill]

No Neale.
The back side of the plate is probably 35 years old, green, like gunmetal. It would take some serious polishing.

PS. Maybe I could make a new plate from very flat copper sheet from the scrap yard. Or polish it very well. Cheaper, & if it don't work, put it back together?

[MrCramp]

Any small engineering shop will put your plate on a machine (lathe??) and skim it so it goes flat. This is a common problem with any water pump and should cost £5-£10 ish cash. You can also clean up the other side of the plate and reverse it. Much, much cheaper than any other solution.

[Spyro]

No Neale.
The back side of the plate is probably 35 years old, green, like gunmetal. It would take some serious polishing.

PS. Maybe I could make a new plate from very flat copper sheet from the scrap yard. Or polish it very well. Cheaper, & if it don't work, put it back together?

Use the green side, a bit of wet and dry sandpaper should get it shining without much effort. I'm not one for changing every year but 10 years is way to long to leave an impeller

[JimC]

You could take a look here: http://www.kpm-marine.com/rebuildkits.html they do refurbishing kits for your pump.

[barnaclephill]

Thanks guys.
Will turn the cover plate over, polish it well with wet'n'dry and have a good look at the worn/raised area how it interacts with the present and then the new impellers.
If that doesn't work so well I'll go down the path of a new coverplate (same cost as per KPM 2nd Breath rebuild kit) or rebuild kit itself.
Thanks