Date:         Thu, 15 Aug 2002 20:43:38 -0400
Reply-To:     Dennis Haynes <dhaynes@OPTONLINE.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Dennis Haynes <dhaynes@OPTONLINE.NET>
Subject:      Re: Transmission cooler
Comments: To: 72510.1173@COMPUSERVE.COM
In-Reply-To:  <00b201c24398$5852b320$0f28c1d8@mydomain>
Content-type: text/plain; charset=us-ascii

The transmission pump is definitely a positive displacement pump
designed to produce hydraulic pressure required to operate the clutches
and valves. Most of the heat in an automatic transmission is developed
in the torque converter. The Vanagon converter is heavily finned and
does an excellent job keeping itself cool. In fact, the air cooled
busses use this set up with no additional cooling at all. The first step
would be to measure trans oil temp and see if you even have a problem.
If you decide you need an external cooler, remove the stock cooler from
the front of the transmission, block off the coolant hoses and get 90
metric fittings to attach hoses to the transmission. An additional
advantage of this is to keep the transmission heat from getting into the
engine cooling system.

Dennis


-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of Helen Fahy
Sent: Wednesday, August 14, 2002 9:42 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Transmission cooler

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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