am I right

kds said:

If the pump has any play in it just change the bloody thing and come back and tell us its fixed please !

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We are having a technical discussion **** off newbie

Marine motor drive assembly - US Patent 6361388 Description

interesting article describes shaft venturi effect with a lighter molecule and a denser molecule

ie grease denser

ie water lighter

or in our case coolant v air

fanatic said:

Stroppy? not in the least and if you had read the symptoms there was zero leakage unless motorway run.

Therefore your hypothesis is floored as the system went beyond any possible negative pressure from cold and when normal operating temperature still dragged air in.

Only when stopped after motorway run did it leak.

Further to this as centrifugal forces throw outwards how can you be so sure there is any coolant behind back of impeller and pump body if the clearance is small enough?

Causing a venturi effect

How to build a homemade DIY Venturi to aerate your pond water venturis aeration oxygenates
Please feel free to discuss

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Yeah thanks but i know how a venturi works. I can see where your coming from. But with engine cold there is little or no flow through the impeller. It is just thrashing water around, if there is no flow there can be no venturi effect. When the flow starts as the thermostat opens a positive pressure exists within the system. It would have to be a serious venturi effect to draw air into a closed pressurised system. I don't think that sort of flow is available at tickover speeds. As someone else has said and i said much earlier he should change his water pump ASAP. It is an interesting theory though. To test it out i suggest you buy a centrifugal pump and drill a small hole in the casing just behind the impellor and see if it sucks air in or blows water out. Let us know how you get on.

well today I had a test done to see if there were any hydrocarbons present in the air in the bottle and there was none.
It seems the pump suggestion may have some ground!!
Nick.

wammers said:

Yeah thanks but i know how a venturi works. I can see where your coming from. But with engine cold there is little or no flow through the impeller. It is just thrashing water around, if there is no flow there can be no venturi effect. When the flow starts as the thermostat opens a positive pressure exists within the system.

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If thermostat is A/fitted or B/ closes properly??

redhand said:

If thermostat is A/fitted or B/ closes properly??

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Well of course, but if the bottom hose is missing that would also stop the water pump sucking air. For the purpose of this exercise can we accept that there is a thermostat fitted and it is closing properly. The OP does not complain about the temp gauge failing to rise. In fact a think he said everything was normal other than little air bubbles.