Water Pump Differences

[06SubLegTx]

Hello,

 

I read a article from a builder that recommended using a water pump that cooled better because the fins were more closed off than most that you see. He said that with the Closed Fin style, the cooled was forced into a more narrow patch/direction, versus the open style with allows the coolant to kind of cavitate and stay stagnant.

 

Do they make a Closed Style for the 60 Legacy 2.5i non turbo?

 

Thoughts?  See Images below 

[Dj7291993]

Cavitation is a very different thing from poor flow.  Cavitation is caused by the vacuum created by the pump.  It is essentially a vacuum bubble that opens in the coolant.  When it collapses, it creates a small plasma jet that can turn the metal into swiss cheese.  There are additives put in coolant to prevent this, so it is usually caused by improper maintenance.  Though, a lot of manufacturers have gone to plastic impellers to help prevent this, so using an aftermarket pump with a metal one can cause it.  IIRC, an incorrect thermostat can also lead to too strong of a vacuum, increasing the chances of it.

 

As to the better flow, I can't tell you for sure, though I imagine it's not a huge difference, since the block behind it closes them off pretty well.  I'm not a builder though, so I can't argue from experience.

[06SubLegTx]

Cavitation is a very different thing from poor flow.  Cavitation is caused by the vacuum created by the pump.  It is essentially a vacuum bubble that opens in the coolant.  When it collapses, it creates a small plasma jet that can turn the metal into swiss cheese.  There are additives put in coolant to prevent this, so it is usually caused by improper maintenance.  Though, a lot of manufacturers have gone to plastic impellers to help prevent this, so using an aftermarket pump with a metal one can cause it.  IIRC, an incorrect thermostat can also lead to too strong of a vacuum, increasing the chances of it.

 

As to the better flow, I can't tell you for sure, though I imagine it's not a huge difference, since the block behind it closes them off pretty well.  I'm not a builder though, so I can't argue from experience.

Thank you, it all make since and you obviously know more about cavitation than I do..

[Fairtax4me]

I've never had a problem with a Subaru water pump not cooling properly.

If the engine is running hot there are a handful of things that cause it, a failed water pump wouldn't even make my list of possibilities. It just doesn't happen unless there is severe neglect of the cooling system. (Never changing the coolant)

If changing the pump during a timing belt service, Use a quality water pump like Aisin and you'll never have a problem with it.