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Replacing the Oil Sending Unit on a C5

Technically Speaking

James Berry May 22, 2018
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Q I have been a Corvette owner for as long as I have been driving, and love the magazine. I currently own a ’01 Corvette and for the second time in two years my oil pressure sending unit has failed. When I came out of work last week and started the car the oil pressure gauge was pegged at 80.

The last time I did this I had to remove the upper intake to access the oil sending unit and I don’t want to do that again if I don’t have to. I remember someone at a car show telling me you could replace the oil sending unit without removing the upper intake. I believe it involved drilling a large hole at the back of firewall and then patching the hole. I was hoping you could help me with this?
Thanks,
Mike

A I think I can help. The oil sending unit is a common failure item on C5 Corvettes. Mike, first of all, you do not want to cut a hole in your firewall. There is a way you can access the oil sending unit easier by cutting a hole in the cowl, but you should be able to change the oil sending unit without having to cut any holes at all or having to remove the intake manifold.

The oil pressure sending unit is located on the driver-side top rear of the engine under the cowling between the firewall and the intake. The sender is a small cylindrical sensor with a metal base and plastic upper connector.

Oil Sending Unit Removal Procedure

02 Technically Spaking C5 Gauges Oil Sending Unit 2/5

Remove the plastic cover over the valve cover from the driver-side of the engine. Just pull it up and it should pop off easily.

03 Technically Spaking C5 Gauges Oil Sending Unit 3/5

Locate the oil pressure sending unit; it’s located on the driver-side top rear of the engine between the firewall and the intake. Release the locking clip from the top of the oil sending unit. If you use a pick with a 90-degree at the end of the pick it will make it much simpler to unplug the connector from the sensor since it is almost impossible to reach with your hand. Use the pick to release the locking clip and pull the connector straight off the oil pressure sensor.

04 Technically Spaking C5 Gauges Oil Sending Unit 4/5

Remove the sensor by using an oil sending unit socket and a ball-style swivel universal. Tighten the oil sending unit making sure you keep the socket straight on the sensor so you don’t crack the plastic body of the sensor.

05 Technically Spaking C5 Gauges Oil Sending Unit 5/5

Plug the wiring harness connector back onto the top of the new oil sending unit. When you reinstall the wiring connector back onto the new sensor you may want to use a pair of long needle nose pliers. Push the wiring connector down until the locking tab engages the tab on the sensor body.

I have seen people use a hole saw or a Dremel to cut an access hole in the cowling so the oil sending unit can be accessed without using a ball style swivel universal. I personally do not like the idea of cutting a hole in the cowling. Even with an access hole you are still going to have the same difficulty unplugging the wiring connector from the sensor unless you make the access hole large enough to get your hand into.

Well, Mike, I have done quite a few of these oil sending units and have never had to cut an access hole to reach the sensor. So good luck and let me know how it works out. Vette

Photos by James Berry

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