Water pump - opinions please

[widdowson2008]

Edit: Bugger, Done it again Could some lovely mod shift this to the techie section pleeeeeeeeeaaaaaaaaaaase?
Thank you whoever shifted it
Could you take a look at the pics below and tell me what you see? OK, I know it's a water pump , but what can you tell me from the pics?
The impellor is firmly fixed to the shaft and there is no discernable play in the bearings or lateral end movement.

[jaylee]

A bit of lime-scale build up??

[B*Witched Blingo]

Has something been rolling around in there to take the tarnish off. Is/was the jiggle pin in the thermostate? Just a thought.

[helen&tony]

Hi Steve
Without holding it in my hands, I can't see, but several blades seem to have a fair bit missing towards the centre hub from the way i'm looking at the picture....but that may be my eyesight!...a bit of imbalance as well as poor pumping.
If the impeller is aluminium, it looks like some of the corroded samples I've analysed, and something is sadly wrong with the coolant...maybe a spot of etching, chemically, or even electrolytic action
Cheers
Helen

[bigdaddycain]

Been used in a bongo with no antifreeze?

[munroman]

If it is limescale, then there looks a distinct flow pattern showing in the 'plate out' on the impeller, in plastic machines this typically happens in areas of low or stagnant flow, a bit like silting in a river where it runs slowly.

Except logic would have it that the outer parts of the impeller would be moving faster, so less likely to have 'plate out'.

Cavitation, turbulent flow where the water exits the pump maybe? - Just thinking aloud!

Go on, enlighten us!

[jaylee]

Is this a clue?

[mikexgough]

It leaks....

[jaylee]

It leaks....

It squeaks...?

[jaylee]

It was an extra on Twin Peaks....

[vanvliet]

Nothing to do with this but -
Nice to see metal impeller blades. My VW passat was left with no coolant circulation at all when the VW original pump fitted with plastic impeller cage disintigrated a few weeks ago which blew the head gasket etc etc - - -

[g8dhe]

It could be corrosion or cavitation difficult to tell without much closer view of the damaged areas. Normally with corrosion you will see the corrosion products that are usually black or very dirty brown but they might be being cleaned off. Whilst cavitation causes the surface to crumble (that can lead to corrosion as well), normally cavitation will be worst on the faster moving edges so you would expect to see it towards the outer edges, which I think is what we are seeing ?

[widdowson2008]

This was never a trick question. I wanted to get opinions rather than sow seeds in folks minds.
To be fair, it is far easier to 'feel' the markings than explain them. A pic doesn't convey their state. The impellor tips appear to be pitted as though bashed with a small hammer. The blades look as though something metallic has been sucked into the centre and thrown to the outer edges (centrifugal force), rattled around a bit, and then thrown out. No metallic bits were found in the pump or outlet section.

To answer the replies (in order of posting)

Not limescale.
jiggle pin? don't think so, but it is what I would expect to see if something solid had been through the pump. My first thoughts actually.
The blades are in tact, but 3 of them are bent as though they have been striking something.
Impellor isn't aluminium (pressed steel I think).
No antifreeze? Couldn't say. Would no a/freeze create this sort of marking? I dunno
Not sure what 'plate out' means munroman. Could you enlighten me?
.....and the prize goes to jaylee (or at least that was one of the things I was wanting you to notice.) Yes, this pump has been leaking. The Bongo in question has been filled/bled several times over the last few weeks, and each time things were OK for 2/3 days, and then it started overheating. Looks as if their was a very small leak at the pump which took a couple of days to rear its head. The owner was told by the garage that he was looking at a new head. Put the new pump in today and rebled. Will monitor the situation over the next few days.

Any further suggestions/ideas would be appreciated.

[munroman]

'Plate out' is when deposits fall out of suspension and settle onto a surface, I used to see it on plastic making machinery, it can be a sign of drops in pressure.

Here is a picture of an impeller which has suffered severely from cavitation, are the markings anything like this?

http://en.wikipedia.org/wiki/File:Turbi ... s_Worn.JPG

If, as you say the impeller is bent, this would have caused severe turbulence within the pump, and all sorts of issues with pressure variation over a small distance.

[jaylee]

.....and the prize goes to jaylee (or at least that was one of the things I was wanting you to notice.) Yes, this pump has been leaking. The Bongo in question has been filled/bled several times over the last few weeks, and each time things were OK for 2/3 days, and then it started overheating. Looks as if their was a very small leak at the pump which took a couple of days to rear its head. The owner was told by the garage that he was looking at a new head. Put the new pump in today and rebled. Will monitor the situation over the next few days.

Any further suggestions/ideas would be appreciated.

I'll pm you my address so you can drop the pump in the post...