RE: [T3] REMOTE OIL COOLER EXPERIENCE (Toby, long)

["Erkson, Toby" <toby.erkson@intel.com>]

Here's a safer way:
http://www.icbm.org/erkson/ttt/engine/full_flow_oil_system/full_flow.htm

Why is it safer?  Here goes...
I spent a LOT of time thinking about my system -- hey, with Jim A. and Keith
P. playing  devil's advocates I gotta play engineer and be on my toes :)
Plus, with the amount of money I've put into my engines I can't afford to
mess things up!  Pressure drops, thermostats, oil temps (overheating,
underheating, and operating temps), and cooler location (in the spare tire
well, above the tranny, under the axle, ???) all played a part in the
decision process.

Oil first enters the filter then goes to the oil thermostat.  No matter
where it goes, it'll be clean.  Now, if it's below 180-F it flows back into
the case before the oil pressure relief valve.  If it's greater than 180-F
it is diverted to the pre-cooler, the 48-plate Mesa oil cooler.  This is a
radiator-type cooler and not one of the inferior tube-and-fin ones.  The oil
then enters back into the case (again, before the oil pressure relief
valve).  Now, should the oil be too hot it then goes into the stock oil
cooler for further cooling; just right or too cool then past, or partially
in, the stock cooler (according to the oil pressure relief valve).  If the
oil is too hot when it enters the pre-cooler a thermostatic fan clicks on
and blows through the radiator to further help cool it down.  It will switch
off if the temp should drop (user adjustable on/off temp).

Note:  Some oil will still pass through the pre-cooler when it's cold.  This
is a function of the oil thermostat as it does not completely close.
According to the thermo manufacturer this keeps foaming, surging and a
stagnation from occurring to the oil in the by-pass loop.

My system setup allows filtered oil to enter the engine and be regulated by
the engine according to the proper operating temp set by the engineers.  The
stock cooling system is never compromised, only assisted, which is why I
call it a pre-cooler and not a secondary cooler which would imply an "always
on" oil cooler, either in parallel or serial, and generally installed after
the pressure relief valve.  The oil thermostat has only one INPUT (the oil
from the filter) and only one OUTPUT (tapped into the case before the oil
pressure relief valve).  Only when the oil is in the thermostat does it
either get routed [when cool] to the OUTPUT and a tiny bit to the bypass, or
[when hot] directly through the bypass loop i.e. oil pre-cooler.  I also
don't like the idea of hot air caressing my 5-speed -- then tranny gets hot
enough, why make it worse?  Plus, when the fan is on I can feel the heat
being blown down and get an small idea of how hot the oil is.

By removing the stock oil cooler and putting in a secondary one or rerouting
it you run the chance of over/undercooling the oil, which isn't good, as
well as undercooling the #3 cylinder head.  Now, I haven't done the math on
the #3 cooling but I think it would be a safe guess that the engineers
worked out the necessary cooling differences involved.

My fan gets its power from the coil so when the car is ON the fan is on.
This allows me to kill the engine then put power back to the coil, thus
allow the fan to continue to cool the oil in the pre-cooler while the engine
is off (yes, it does help).

I've lived on a dirt road for many years with a stock cooling system.  There
was never an issue with cooling problems but the oil cooler didn't leak,
either.  Blowing it out once in a while is a good idea but I truly don't
think dry dust accumulation is a concern.

   Toby Erkson
   air_cooled_nut@pobox.com  <-- Please use this address for email
   '72 VW Squareback 1.6L bored and stroked to 2.0L, Berg five-speed
   '95 VW Jetta III GL 2.0L, P-Chipped, Jamex sport suspension
   Portland, Oregon, http://www.icbm.org/

>-----Original Message-----
>...I have been trying to figure how to put an external
>cooler on my '71 T-3 Automatic. I drive a LOT of gravel roads, and did not
>want a cooler down where the gravel could beat it to death. I also think I
>am plugging my stock cooler with road dust...

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