Turbo cooldown timer on aux water pump?

[tigerdog]

Has anyone **cough GeoffSmith cough** looked at using a timer IC to trigger the electric cooling pump for a short period (say, 1-2 minutes) after shutting off the ignition? If I read the wiring diagram correctly, the pump circuit is energized whenever the fans are off. The timer circuit would simply have to ground the Black/Orange wire 24A for the desired period of time after shutoff. Seems this would go a long way to cool the housing, thus extending bearing life. Thoughts?

[rip]

I was out with some prople who were talking about this the other day. They were talking about a timer which keeps the engine running for 2 minutes.
I have read somwhere that the turbo also needs the OIL flow to cool it down, so this would be consistent.

[tigerdog]

I was out with some prople who were talking about this the other day. They were talking about a timer which keeps the engine running for 2 minutes.
I have read somwhere that the turbo also needs the OIL flow to cool it down, so this would be consistent.

I've seen such timers and I could see how this would be critical on oil-cooled turbos; the Elan's IHI and the popular replacement Garrett GT2560 use both oil and water cooling. I have to believe circulating gradually-cooling water through the turbo would do more good than idling. Seems to me, coolant temp goes up after two minutes of idling unless fans are also running.

[GeoffSmith]

Just about caught up on old posts and then this!

Checking the big diagram, I agree but make sure you ground the cathode side of the diode. I guess the timing will look a bit like this (green is ignition and red is voltage across coolant pump relay):

Coolant Pump Timer.gif

[Foo]

A timer for the pump would be great. regular 'Turbo Timers' are illegal in the UK, as you're not legally allowed to leave a car unattended in the UK with the engine running.

[ailwyn]

I may have missed the point, but I thought the purpose of the electric water pump was to run after the engine is switched off (until the water temp drops to that which would normally turn off the fan switch)?

[Gazza]

I agree with Ailwyn

[GeoffSmith]

I think Doug's idea is to cycle coolant through the turbo for a fixed period after switch off to make sure the turbo cools down, no matter what the coolant temperature happens to be.

[tigerdog]

I think Doug's idea is to cycle coolant through the turbo for a fixed period after switch off to make sure the turbo cools down, no matter what the coolant temperature happens to be.

Precisely. Without doing this, the coolant in the turbo housing is exposed to the housing's heat, with only the hope of thermo-syphoning to move coolant through the bearing. I think I'd prefer a more positive approach.