Water pump - opinions please

[widdowson2008]

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.

Markings not quite like your example. More like a small metal object getting thrown around, pebbledashing the impellor.
Only 3 of the 6 blades are actually 'bent'/deformed, suggesting that some object has been thrown around by the blades. Would this cause the pump to be less efficient? Trying to get some facts together which agree with what has been experienced.

[widdowson2008]

.....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...

Don't tell me you are going to start pulling things to bits . although it would be nice for folk to realise that it's not only me who has this phobia. I'm not a pervert. Honest.
.....and are you saying that you are a pump guru? Yeeeeeeaaaaaaaaaaahhhhhhhhhh

[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...

Don't tell me you are going to start pulling things to bits . although it would be nice for folk to realise that it's not only me who has this phobia. I'm not a pervert. Honest.
.....and are you saying that you are a pump guru? Yeeeeeeaaaaaaaaaaahhhhhhhhhh

No, i was gonna modify & use it as a self cleaning ashtray...

[munroman]

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

Markings not quite like your example. More like a small metal object getting thrown around, pebbledashing the impellor.
Only 3 of the 6 blades are actually 'bent'/deformed, suggesting that some object has been thrown around by the blades. Would this cause the pump to be less efficient? Trying to get some facts together which agree with what has been experienced.

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.

[widdowson2008]

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

Markings not quite like your example. More like a small metal object getting thrown around, pebbledashing the impellor.
Only 3 of the 6 blades are actually 'bent'/deformed, suggesting that some object has been thrown around by the blades. Would this cause the pump to be less efficient? Trying to get some facts together which agree with what has been experienced.

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.

And could this make it difficult to bleed?

[jaylee]

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

Markings not quite like your example. More like a small metal object getting thrown around, pebbledashing the impellor.
Only 3 of the 6 blades are actually 'bent'/deformed, suggesting that some object has been thrown around by the blades. Would this cause the pump to be less efficient? Trying to get some facts together which agree with what has been experienced.

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.

Causing an unbalance in the propeller spin & cutting down on efficiency regarding coolant circulation??

[munroman]

I am not sure if it would make things difficult to bleed, but instinct says it can't help!

When the pressure varies all sorts of funny things might happen, just look at a bottle of pop when the top is taken off and see the bubbles coming out of suspension when the pressure drops.

[widdowson2008]

Bit out of my depth here and not fully understanding.
According to Ady, this particular Bongo was not responding as he would expect as the norm during bleeding. With the new pump on, it apparently does respond as expected. I witnessed all this but purely as a spectator. Ady is the one to expain more fully what he means and perhaps he'll chuck in his 2 pennorth when he gets back from work.
Bit vague I know.

ADY - HEEEEEEEEEEEELP

[jaylee]

My view is a dodgy pump may not circulate coolant so well regardless of how tight the system is... Heat dissipation would be hindered... Possibly!??? I ain't no expert!

[Northern Bongolow]

thanks steve .
this bongo would not bleed correctly.it airlocked, the front heater had to be bled manually by litterally taking off the pipes.
when bleeding it as in the youtube videos, it was noted that the flow around the system was very poor,as all the system had been flushed,and at least half the coolant pipes were removed,this was very odd to say the least.new gen mazda stat had been fitted, new oem main rad fitted previously.front and rear matrix's were good.
the only thing i could think off was that the internals of the pump were in some way defective as the pump appeared ok externally(belts ok etc). apart from the leak.the leak shown is from the hole in the casing which is at the 6 oclock position on the pump,this hole cannot be seen while the pump is on,unless you remove the belts,you can only see the other hole at 10 past (view from the alternator side).
as i couldnt be there today steve and the owner did the pump replacement today and found what you see pictured.
i must admit to expecting the internals to be in a worse state,but am glad for the owner that at least he has an end to his problems (i hope).

i will leave the owner to write a summary of his woes if he wishes to do so.

[widdowson2008]

Possible cause of bent impellor blades.
Helen sent me an email this morning with a very logical reason for the bent blades. ICE!!!!!

Think about it. In the recent very cold weather, if coolant had started to freeze and formed ice within the pump housing, when the engine is started a chunk of ice is getting thrown around in the pump with no way of getting out. It will eventually get broken up by the constant battering and melt, leaving absolutely no trace.
This would explain
1 - bent impellor blades (chunk of ice getting hammered and breaking up) and secondly
2 - pebble dashing/sandblasting (pitting is probably a better way of describing it) of the blades as the ice breaks up into smaller bits
3 - no evidence left cos it has melted (glass bullet theory)

Ice can do a lot of damage to metal. Think about the Titanic.

That works for me.

[helen&tony]

Hi Steve
No such thing as an ice bullet, as when propelled in a rifle/ pistol, bullets are designed to change shape in the area immediately preceding the rifling in an area known as the forcing cone, and the metal changes in order to engage the rifling more efficiently. Thus an ice bullet would shatter, being of a non-malleable material.
It might be possible to stretch the imagination oh...about a million miles , and fire a large ice ball in a big-diameter musket (non-rifled), using the "patched ball" technique used in smooth-bores, where a ball is wrapped in cloth often lubricated in a mixture of tallow and bees-wax . Again. it might even be possible to use a saboted* ice-bullet, but bear in mind that any attempt to load a piece of ice is going to involve a degree of handling, and unless "Secret Squirrel" the master assasin carries round a dewar flask of liquid nitrogen to dump the ice-bullet in for a quick per-firing chill, then a hand-grenade would provide a better job when fired from a grenade launcher...quite untraceable
Ah....where were we???...yes, ice can muck up a pump rotor, and it could show that the engine concerned had been run without antifreeze...

* Sabot is the French word for Clog, and striking underpaid machine workers in the cloth trade in France many years ago would throw a clog in the works of the machines to stop them working...thus naffing up a machine by throwing a clog in , became known a "Sabotage"
It also refers to a separate casing round a bullet, designed to protect it in firing, and disintegrating upon exiting the barrel, thus allowing the bullet to travel unharmed along the barrel.
Such a protective case is designed to propel a smaller diameter bullet at colossal velocity, and travel further than it's mass would normally allow it to travel under non-saboted conditions
Cheers
Helen

[widdowson2008]

Bit more info.
First off, I took a vernier to the old pump to find out extent of bending on impellor blades. I was wrong . They are not bent - just badly pitted. The shape of the blades is quite convolute and the 'bent' appearance was (and still is) an optical illusion. Sorry if I misled folk. Not intended.

The rattle? I seem to remember reading a post describing this rattle a month??? ago. Have done a trawl but can't find owt. Not my imagination - I definitely read it (I think), but she confirmed it to me the other day verbally.
The event took place last November'ish, before the cold weather set in (ruling out the ice theory) and she explained it was as follows: .

Out in van doing school run or shopping, and there was a rattle from the engine. It lasted approx 30 seconds and then stopped.
Mazda gauge shot up indicating an overheat, and then went back to normal.
On return van taken into garage to investigate. Nothing found but mechanics started talking in terms of a new head being required.
Van bled as per factsheet.
After two and a half days, the van started chucking out coolant. Re-bled several times with same end result.
When we took the pump off, the blades sort of suggested that this was where the rattle came from.

[Northern Bongolow]

just thinking steve that the rattle was in fact the pump spinning in a dry state,as in an air lock situation, the water in the pump would normally dull the sound. as we have seen, it was sucking air in at this point and leaking coolant.

[widdowson2008]

just thinking steve that the rattle was in fact the pump spinning in a dry state,as in an air lock situation, the water in the pump would normally dull the sound. as we have seen, it was sucking air in at this point and leaking coolant.

Does a dry pump rattle? and if so, what is the pitting caused by? Sorry to labour this, but they ARE pitting marks.