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recycling pump
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recycling pump
by mikecg » Tue 04.08.2026, 10:32
Hi can someone tell me, does the recycling pump help cool a running engine when the high temperature is reached and the fans come on. Currently the fans come on, the recycling pump does not will remove at some point and check it). I have taken out the thermostat (not sure if it is working) and in this hot weather the car holds a temperature hovering in and out of the last quadrant on the temperature gauge.
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mikecg - Enthusiast
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Re: recycling pump
by dapinky » Tue 04.08.2026, 13:00
Short answer = no.
Longer answer - the system is designed so that the mechanical water pump (driven by the cam belt) flows water through the engine, and then the radiator once the thermostat opens.... and also through the heater matrix if the valve is open.
If the coolant gets to the temperature threshold (107C IIRC) then the fans will kick in and operate until the temp comes down to 100C (again, IIRC) - the "problem" is that these numbers, whilst being quite close together, give a large deflection on the temperature gauge in the car, so it appears to be more dramatic than it really is. Basically, 1/4 on the gauge is 'normal', 3/4 is when the fans cut in, and 1/2 is when they stop again....... but all within less than 10C overall.
The electric recirculation pump is wired in such a way as to work on exactly the same set of recorded temperatures, but only works with the ignition switched off. The theory being, that if the car was over 107c (with the fans running) when the engine is switched off, the pump will then run until the temperature drops to the 'safe' value....... it is intended to keep coolant flowing throught he engine block and, specifically, through the turbocharger to prevent localised heat build-up which can cause problems.
It is important to note that the electric pump actually sends coolant in the opposite direction through the engine/turbo than the mechanical pump...... so trying to get both to work at the same time will cause major overheating problems, and will cause the electric pump to fail quite quickly.
Testing the electric pump is done the same way as testing the fans (directly ground the earth connection), but with the ignition off, as opposed to on for testing the fans.
It is a bit of 'overkill' for most people, as generally, a driver wouldn't turn off an idling car whilst the fans were still running - but there may be times when it is either necessary or just convenient to do so, and that is when it comes in to play.
Longer answer - the system is designed so that the mechanical water pump (driven by the cam belt) flows water through the engine, and then the radiator once the thermostat opens.... and also through the heater matrix if the valve is open.
If the coolant gets to the temperature threshold (107C IIRC) then the fans will kick in and operate until the temp comes down to 100C (again, IIRC) - the "problem" is that these numbers, whilst being quite close together, give a large deflection on the temperature gauge in the car, so it appears to be more dramatic than it really is. Basically, 1/4 on the gauge is 'normal', 3/4 is when the fans cut in, and 1/2 is when they stop again....... but all within less than 10C overall.
The electric recirculation pump is wired in such a way as to work on exactly the same set of recorded temperatures, but only works with the ignition switched off. The theory being, that if the car was over 107c (with the fans running) when the engine is switched off, the pump will then run until the temperature drops to the 'safe' value....... it is intended to keep coolant flowing throught he engine block and, specifically, through the turbocharger to prevent localised heat build-up which can cause problems.
It is important to note that the electric pump actually sends coolant in the opposite direction through the engine/turbo than the mechanical pump...... so trying to get both to work at the same time will cause major overheating problems, and will cause the electric pump to fail quite quickly.
Testing the electric pump is done the same way as testing the fans (directly ground the earth connection), but with the ignition off, as opposed to on for testing the fans.
It is a bit of 'overkill' for most people, as generally, a driver wouldn't turn off an idling car whilst the fans were still running - but there may be times when it is either necessary or just convenient to do so, and that is when it comes in to play.
Dave
Just the one now, but this one's mine! - and it will be finished eventually..... - but also temporary custodian of a project until it is finished enough for Angie to drive it
...oh, and a 2006 Freelander destined for the jungles of The Gambia - 4500 miles across roads, desert and tracks - what could possibly go wrong?
Just the one now, but this one's mine! - and it will be finished eventually..... - but also temporary custodian of a project until it is finished enough for Angie to drive it
...oh, and a 2006 Freelander destined for the jungles of The Gambia - 4500 miles across roads, desert and tracks - what could possibly go wrong?
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dapinky - LEC Administrator
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