Date:         Wed, 14 Aug 2002 09:41:50 -0400
Reply-To:     72510.1173@COMPUSERVE.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Helen Fahy <72510.1173@COMPUSERVE.COM>
Subject:      Transmission cooler
Content-Type: text/plain; charset="iso-8859-1"

What kind of pump does the automatic transmission use to circulate
transmission fluid through the transmission oil/water cooler?

The engine oil pump is a positive displacement pump and up to the oil
pressure relief setting, the pump increases oil pressure to overcome
pressure drops while maintaining oil flow rate (for a constant oil
temperature).  So when I add an oil cooler, the pump increases its outlet
pressure to make up for the additional pressure drop incurred by additional
fittings, piping and the oil cooler.

I am considering adding a tranny cooler in addition to the oil cooler that I
am installing.  I am concerned that the transmission oil pump, if not a
positive displacement pump, may ride up the pump curve and starve the
transmission of oil.  Can anyone shed some light on the issues of installing
a transmission oil cooler?  Perhaps I would need to install an accessory
pump in series to overcome the additional pressure drop of the tranny cooler
and its fittings.

Has anyone ever monitored the temperature of the automatic transmission
under varying load and ambient temperature conditions?

Thanks,
Helen & Joe Fahy
'87 Westy


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