Water pump impeller question

[manc]

Hi,

My car is actually a 94 1.4 Golf with an ABD engine, which, I think, has the same water pump as some Polo's, maybe even the G40, as it has three bolt slots and also tensions the timing belt.

So my question is, do these pumps have plastic impellers which can deteriorate, come loose or lose their fins etc? as my engine seems to be suffering from poor circulation and I would like to hear some voices of experience about these pumps and their impellers before I have a look.

[Jezza-7]

Most of the water pumps have plastic impellers now days. My old one which was original had metal ones, but when i exchanged it they gave me a plastic impeller one.

And yes they can loose impeller fins over time, my mates had lost 2 fins off his pump.

[manc]

Symptoms are.

The engine has started to run hotter over some months, otherwise, it runs fine with no steam in the exhaust or water in the oil. I suspected a failing thermostat and so replaced it, plus a rad temperature switch, with no improvement, as the temperature gauge still soon climbs to 95-100 on short journeys, and doesn't come down from air blast when driving at speed.

I then tried running it without a stat, and the engine ran over-cool when driving at speed, but when idled the temperature built gradually and the fan kicked in with the gauge on 91 and out at about 85 perfectly.

Conversely, with the stat back in, when idled, the engine gets hot quicker, the bottom hose doesn't get hot until the gauge reaches 90 (and then slowly) and maybe tellingly the fan doesn't kick in until the gauge reaches 95-97, doesn't stay on long and only returns the gauge to 90, the heat cycles are short and the bottom hose feels almost as hot as the top!, ie; it shows little or no temperature drop.

I also tried back-flushing the system and tested to see how good the flow is through the small bore pipe which goes to the header tank by disconnecting it and holding the end over the open tank, and when idling the engine from cold it's a trickle which doesn't increase much with more revs, and when also on idle, the trickle stops altogether when I hold this pipe vertically?

All of which makes me think the problem is being caused by poor circulation from a damaged impeller, instead of the more usual suspect of a head gasket, but I'm always open to suggestion.

Manc

[PeteG40]

well they are only about £40 exch from vw.  Obviously do the timing belt at the same time - which is a 4 yr/60,000 mile interval anyway.

[manc]

Thanks for the advice, will have a look when the rain blows over.

Can only add, I wished I had one of those flexible endoscopes to stick down the tube that runs into the back of the pump, to have a look at the impeller beforehand.

Must put one on my Christmas list.

Manc

[manc]

My pump was OK the problem was the head gasket which was borderline nearly everywhere!

Car now fixed.

Thanks for the replies,

Manc