Dry Sump Corvette Engines
Posted to Technical Tips Forum on 9/5/2015
76 Replies
Lately, we've been seeing more dry sump Corvette's serviced
by oil change and independant facilities with incorrect oil
change procedures. Overfilling the oil in a dry sump
Corvette can be disasterous and can cause hydrolocking and
bent connecting rods in severe cases. If you give oil
changes to your least skilled tech, make sure that he knows
exactly what he is doing if he services one of these
vehicles.
Yesterday, a customer came in with a 2014 Vette with a
complaint of smoking badly, running rough and Service Engine
light on. He stated that he had his oil changed in a quick
service facility and it started smoking soon afterwards. He
returned to the facility and they said that the oil was
overfilled and drained an undetermined amount of oil from
the vehicle. His problems increased and he brought the
vehicle in to us for repairs.
I checked the oil level and it was correct. Removing the air
intake tubing, I saw it was filled with oil at least 1 inch
deep. The air filter and the MAF were heavily oiled and oil
was dripping from the air box. The oil in the intake was
dirty and did not appear fresh.
We gave the customer a repair estimate (not warranty) and he
called the oil change shop who sent 2 people over to inspect
the vehicle. They said that they did nothing wrong, just
drained the oil, poured in 5 quarts of oil and let it go. I
told them that the system held 9.8 quarts and they said that
couldn't be since 5 quarts overfilled it and they needed to
drain some back out.
On a dry sump Corvette, there are 2 oil drain points. If you
only remove the drain plug in the front of the oil pan, only
2 quarts or so will come out from the sub-pan. The rear
drain will drain the main pan and the oil tank. It seems
that they drained the sub-pan only and added 5 quarts,
overfilling the system by 3 quarts. On top of the oil tank,
a vent tube leads into the air intake. An overfilled system
will vent all that excess oil directly into the intake
tubing. That's why the oil still looked dirty, it was never
replaced, just added to.
So, be cautious. This was a 600 beans mistake, I saw a
similar case on a ZR-1 that locked up the engine and bent 2
connecting rods. That was a 9000 beans mistake.
James from Florida
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