Even since the car was new, on hot summer days my 1980 BMW 320i
would run hot, especially with the air conditioning running.
I have the 1.8L 4-cyl with manual 5-speed transmission, which
only produces 105HP. As underpowered as it is, it still ran
too hot, even at highway speeds on hot summer days with
or without the air conditioning on.
Air Conditioning systems were all add-on that year, as there was
no factory air for that model. The OEM radiator was not adequately
sized to be cascaded behind the add-on A/C condenser, and still keep
the engine cool on hottest summer days.
Hard wiring ON the electric auxilary cooling fan for the condenser side
and the addition of plastic fan shroud on the engine side had little
or no cooling effect.
I searched high and low for an oversized radiator for the
E21 body, but to no avail.
So, I designed one myself.
I made a template (sketch) for a custom down-flow radiator
with the same inlet and outlet configuration as the OEM,
except maximizing radiator core dimensions to the limits of
the E21 body. The result was a design that requires only
one 5 minute modification lower radiator mounts.
I got estimates for the project from two custom radiator
companies: Griffin Radiators/Anderson, SC and Ron Davis
Racing Products/Phoenix, AZ.
I went with the Ron Davis estimate and 6 weeks later had
the radiator delivered to my doorstep for $638 (including
Its an all aluminum design (no epoxy), with nearly twice the
core area as the OEM at that same core thickness.
Performance is amazing. With the oversized custom
design, I've yet to see the operating temperature reach
the half way mark on the gauge.
The gauge half-way point use to be the lower limit temp
with the OEM radiator. The OEM radiator allowed
the temperature to travel to full scale on hot days, on
the verge of boil over. Having to run the cabin
heat on hot summer days on beach trips just to
keep the engine from overheating got to be a real
Pictures of the OEM vs Custom, and installation
can be seen at www.bmwboard.com in the 3-Series
FORUMS area. Just look for the post from:
Z4madehere and titled: "1980 320i Runs Hot"
Hopefully posting here will gives future
folks with a similar condition at least one
valid search result.