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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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