auxilary water pump, i think problem solved!

[rubberdubber 0]

My auxilary water pump was disconnected when i bought my corrado vr6, some people say leave it disconnected others say connect it, i was under the illusion it only ran when the ignition was off for a short time. But after searching on here it would appear it runs all the time the ignition is on? this made me think its probably a good idea to have it working.

 

Anyhow i re-connected it and it still didnt work, traced the wire to the fan control unit and looked at the pin diagram on the unit and it appears that theres no output to where my auxilary pump wire goes, hmmm odd. anyhow looked on etka and realised i have the incorrect control unit. Part number of the one fitted to my car is 1H0 941 597.

 

according to etka it should be 1HO 919 506 A

 

looked on ebay for them and sure enough the correct part has a pin labelled WP, assuming this is the auxilary water pump :) £14 inc. postage, fingers crossed it works!

[Kevin Bacon 5]

Nice one!

 

For further troubleshooting if that doesn't work out, pins 1 & 4 of the yellow temp sender control the fan after run and also the pump when the ignition is off.

 

As for the pump itself, it's just a booster pump for the heater matrix and to ensure there is hot air still when the engine is turned off, so it's up to you if you run it or not. The engine certainly won't go into meltdown without it :D

[Jim Bowen 1]

is the aux pump meant to start as soon as ignition is on?

 

replaced mine and it seems to be on all the time, i thought i had a problem with it.

[Kevin Bacon 5]

Yep it runs permanently on the ignition..... that's it's 'booster' element. The aux pump and a restriction in the top hose (the one that Tees off to the throttle body) ensure the hot water hangs around in the matrix for as long as possible to maximise heat transfer.

[Jim Bowen 1]

Good news, i've never been too sure and thought i might of wrecked the pump by now and it wasn't cheap from VW.

 

cheers

[RW1 0]

The Auxiliary Electric Coolant Pump is designed to prevent boiling in the head after shut down by continually circulating coolant.

 

This Auxiliary Electric Coolant Pump helps to keep the coolant flowing in hot climates or under high loads on the engine or heating system.

 

The Auxiliary Electric Coolant Pump circulates engine coolant anytime the ignition is switched on

 

The Auxiliary Electric Coolant Pump runs when the engine is switched off and the coolant temperature goes over 107° C, switched on by the "Yellow Sensor" in the thermostat housing. It runs in conjunction with the Radiator Cooling After-run System switched on by the "Yellow Sensor" in the thermostat housing. Circulating the coolant during this time helps cool the engine block and prevent the possibility of air pockets forming in the cylinder head.

 

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[Kevin Bacon 5]

That's a myth. It's a heater booster pump.

[RW1 0]

Tell VW then. Thats their text summarised!

 

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[Jim Bowen 1]

i looked at my temp sensor things, the other day, and is it normal for the yellow one to sit further out than the other two.

 

mine doesn't look pushed in as far as the others

[RW1 0]

As long as the securing clip is in place in the sensor socket wall slots, with the all metal body behind clip on the thermostat housing side, its OK. Yes, it does sit a little more proud then the other two.

 

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[Kevin Bacon 5]

Tell VW then. Thats their text summarised!

 

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Which text?

 

All I can see is a very small pump that forces water through the matrix and then out through a tiny little hole in a plastic splitter. If that circulates 10 litres of water around the head and block, my name's Uncle Ben.

 

What's interesting is I ran my VR6 with no aux pump for over 60K miles with no adverse affects other than the heater not being quite as hot as it was with an aux pump.

 

What's also interesting is my BMW has an aux pump, as does my Polo, neither have engines which are prone to heat issues, but if VW tout is as being a pump for removing localised hot spots, even though water does that itself naturally, then who am I to argue :D

[RW1 0]

Some of the extract is on the doorstep! http://the-corrado.net/showthread.php?270-VR6-Tech-Info&highlight=vr6+study+402

 

Under "Engine Cooling System". The text has omitted some of the information contained in the SSP402 (USA).

 

All I can see is a very small pump that forces water through the matrix and then out through a tiny little hole in a plastic splitter. If that circulates 10 litres of water around the head and block, my name's Uncle Ben.

You shouldn't be surprised at "heat losses" in pipes. A good example is the pipe cooler for the Corrado's power steering in the bumper frame.

 

So they are using the heater core to dump heat when the main mechanical pump is not running. Temperature drop is most likely enough to dissipate the localised heat by sending into the rubber pipes & core in the afterrun mode. In normal mode with main pump running, its making sure the coolant is servicing the head.

 

What's interesting is I ran my VR6 with no aux pump for over 60K miles with no adverse affects other than the heater not being quite as hot as it was with an aux pump.

 

Maybe so but the engine has to operate in several enviroments/countries, so they compromise on a design to cope with most markets to reduce scale costs of production. May not make a difference in the UK but elsewhere at say 40'C air temperatures, VW will have seen problems during development.

 

And the dash temp gauage is only one spot in the engine. The only other one that can used is the two radiator thermoswitches in the radiator and they are only a basic crude piece of information. So goodness knows what is going on in the cylinder head.

 

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