Whether you sourced your engine from a dealer as a crate engine or as a take-out from a salvage yard, there are components you may not want to keep. The car LT-series engines have a factory water-to-oil cooler mounted to the rear driver side of the block which doesn’t clear the chassis in most vehicles, and all the truck engines (L83/L86) have vacuum pump on the driver side front of the block that is driven off a belt on the accessory drive. The pump won’t clear most front crossmembers and is not necessary for swaps. Deleting these items is not difficult, but you do need some special parts to make it happen.
The factory oil cooler is not huge, but it just doesn’t clear the chassis in most applications. Deleting this cooler is most common solution. For most chassis, the cooler just doesn’t clear the crossmember in most cars. It will clear some trucks, but you may have exhaust clearance issues as well.
The oil cooler is used on most wet-sump LT1, LT4, and LT5 engines, including crate engines. This cooler mounts the driver-side rear of the block and oil pan. It is a water-to-oil cooler, meaning that engine coolant circulates through the case of the cooler, pulling heat from the oil. This is just like a transmission cooler in the radiator. These are efficient and regulate the temperature of the oil to match the water temp, which keeps the temperatures consistent. Some trucks also come with an oil cooler, but instead of the water-to-oil unit, there is an aluminum block with two aluminum lines that run to a cooler by the radiator. This can be reused as will clear more chassis, but you may want to delete it, the choice is yours.
While cooler oil is nice, for most street cars an oil cooler is just not necessary and the factory unit is too large to clear most frames and subframes without serious modification. The simplest answer is to remove it. There are several options to do so, including the factory components or some trick pieces from Holley Performance.
If you are using a Holley LT swap oil pan, a bypass cover is included like this one. The pans come with the bolts and a new metal gasket as well. The photo on the right shows the factory GM bypass cover. It works well and is relatively cheap, but it does not have any provisions for a pressure port.
There are 2 pieces you need to bypass the factory oil cooler: a water jacket plug and a replacement oil pan bypass cover.
If you are replacing the stock pan with a Holley unit, the bypass cover is included, but if you are using the stock pan, you need a bypass cover. The factory bypass cover is smooth, there are no provisions for any fittings. This works if you are using an ECM-derived oil pressure signal or if you are pulling pressure from another port. If you need a pressure port on the pan, then you need a bypass with a pressure port, such as the Earl's delete port (p/n 1136ERL). If you want to run a front-mount oil cooler, use the Earl's oil cooler adapter plate (p/n 1126ERL). The oil cooler adapter features a thermostat to control when the cooler is open, to allow for quick engine warm up.
If you need a pressure port, a Gen-V Oil Cooler Block Off Plate (left) from Earl's will get the job done. There are two part numbers that will work: 1137ERL, which has 1/8 NPT threads for aftermarket sending units or turbocharger oil supply lines; or 1136ERL, which has M12 threads for a factory sending unit. If you want to run an aftermarket oil cooler or need ports for turbo oiling, the 1126ERL unit (right) from Earl’s is the solution. It also has 2 1/8 NPT ports for pressure sending units. This adapter fits Corvette, OEM Truck, and Holley LT swap pans, however OEM truck pans require a spacer (1127ERL) for block clearance.
The other piece of the puzzle is the coolant port. The coolant travels from the water pump to the cooler, and then from the cooler to the block. There is nothing needed on the front of the engine, but you need a plug for the block. The factory plug (GM p/n 11611351) is a large M27x1.0 thread plug with a very large 17mm hex keyhole. You can use an M10 bolt with nuts threaded on tight as a makeshift Allen key if you don’t have a 17mm Allen key. Another option to plug this port is the Earl’s AN adapter (p/n 97-210), which provides a -10 fitting for any accessories that require a water return line.
These covers come with a metal gasket, the cover, and bolts to secure the plate to the oil pan. You can use the port to supply oil to a turbo or for an oil pressure sender. Holley makes two bypass covers with ports, one for the factory style pressure sensor (M12 x 1.5) and one for aftermarket units with a 1/8 NPT port (p/n 1137ERL).
Just under the knock sensor on the rear upper driver-side is the water jacket port. This must be plugged. Truck engines already have this plugged, but if you have the water-to-oil cooler, it will have a fitting installed, or be open if you have a crate LT1/LT4. The port is shown here with the plug partially installed. You might not have a giant 17mm Allen wrench, so you can use an M10 bolt with a 17mm 6-point head and some nuts or nut and washer combinations to make one as shown here. Make sure you use thread sealant.
On truck engines built from 2014-2018, there is a vacuum pump on the driver-side front. The lower port is the return, the upper port is the pressure side. Depending on your motor mount adapters, these can be used for pressure/feed lines.
If you have a truck engine (2014-2018 L83 or L86), you have a vacuum pump mounted to the front driver side of the engine. The pump is to boost brake assist vacuum, but for most swaps it is not necessary, and it is absolutely in the way for SBC conversion mounts. The vacuum pump itself is easy to remove, but it leaves two oil ports open than must be plugged. You could use these ports for turbo oiling or for a pressure sending unit, but that greatly depends on the motor mount adapters you use, as some will cover the port, making it impossible to mount anything other than a plug in the hole.
The port is an M12 x 1.75 thread. You should use a shouldered plug, such as Earl’s p/n LT0002ERL kit, which is just about the easiest solution. The kit includes 2 plugs. If you want to use the ports, then Earl’s p/n LT0003ERL pressure port plug kit is the one you want. This one comes with one plug and one 1/8 NPT adapter for an oil pressure sending unit.
Earl’s vacuum pump delete plugs are the best way to seal these ports, just make sure you use thread sealant. If you want to use these ports for a pressure sending unit or oil feed, you need the adapter kit Earl's LT0003ERL, which includes one plug and one 1/8” NPT adapter.
The LT1 and LT4 engines come with these ports plugged off from the factory, so you only have to deal with this on truck engines. The vacuum pump was only used from 2014-2018. The 2019 L84 and L87 truck engines do not have the pump.
These items might come as a surprise when you are in the middle of your swap, and if you get an engine from a salvage or individual, you may not even realize that there are open ports on the block. For just a few bucks you can have your Gen V engine sealed up and ready to swap into the vehicle of your choice. Make sure you use thread sealant on all oil/water ports to ensure you don’t get any puddles under your car after the swap is complete.
Some adapter plates cover the pressure port, so you may not be able to use this, depending on the type of adapter plates you have.
