Pascal,
Oil coolers are normally installed on all industrial engines. Do not confuse
water temperature with oil temperature. Petroleum oil rapidly loses its
ability to lubricate when the oil temperature is above 100C. Turbochargers
are lubricated by engine oil and by doing so, absorb a lot of exhaust gas
heat as the exhaust side of the turbo will run at a temperature somewhere
between 600 and 800C. Oil coolers must be installed with a thermostat, just
like your cooling water system, because the oil temperature must also exceed
90C. If the oil does not get that hot, water will build up in the oil and
create sludge. So ,to answer your question, you must connect a temperature
gauge to your oil pan and watch the temperature. It is quite possible that
your usage will not overheat the oil. Bypass the cooler and watch. If your
oil gets too hot, reinstall a new cooler. Oil cooler corrosion is a sign
that you are suffering electrolytic corrosion. Make certain that all
dissimilar metals in the salt water circuit are not electrically grounded,
if that is not possible, use a zinc sacrificial anode and change annually.
Steve
"Pascal Goncalves" wrote in message
om...
Whay turbocharged engines have oil coolers?

I have a Volvo Penta 2003T engine in my 1992's 36 ft sailboat; this
a turbocharged version of the 2003 and it have an Oil Cooler
instaled inline, before the fresh Water cooler. The oil cooler is made
of aluminium with the inner tubes of cooper, and because it uses raw
water, is prone to corrosion. A new one, woul cost to me, here in
Brazil, about US$ 1,200.00 wich I think is unaceptable.

This engine is 45 HP, and has a turbocharge (turbine) but the
operating temperature is not so high; the thermostat begins open at
74 °C and is fully open at 87 ºC; the new Volvo Penta 2040 wich is
not turbocharged and has 40 HP, operate at a higher temperature
(82-95°C) but does not have an oil cooler. Both engines uses the same
lub oil (15W40).

The oil cooler, is a very critical piece, since it can cause the
complete desctruction of the engine, in case of the raw water goes to
the engine lub oil. I am tempted to eliminate this oil cooler
bypassing it and not refrigerating the lub oil at all. What would be
the drawback? I use this motor very lightly, at 2,000 rpm, not at
the maximum 3,200 rpm.

Thanks for the help

Pascal Goncalves
Salvador-BA-Brazi