If you are tackling an engine build or a coolant system overhaul, you know how crucial it is to seal off unused ports properly. A reliable block off plate prevents leaks, maintains pressure, and keeps your engine bay clean. Whether you are working on a Duramax diesel or an LS swap, the right plate makes all the difference.
This guide reviews the best block off plates for coolant and oil cooler bypass applications. You will learn about precision machining, material quality, and compatibility so you can choose the perfect plate for your project. Let’s dive in.
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Artudatech Coolant Block-Off Plate with O-Ring Seal DP0402 for Chevy GMC 6….
Best forDuramax coolant bypass sealing
- OEM-compatible precision fit
- Lightweight and corrosion-resistant
ConsiderLimited to Duramax engines
Saillong 1 Pack LS Billet Oil Cooler Block-Off Plate, Silver
Best forLS oil cooler deletion
- Durable aluminum alloy
- Easy bolt-on installation
ConsiderSingle pack only
Pilida 551693 LS Engine DBC DBW Gen 3 Gen 4 Throttle Body Bypass Cylinder H…
Best forLS steam port capping
- Complete kit with hardware
- Fits all LS engines
ConsiderNatural finish may show dirt
CNRAQR LS Engine Oil Cooler Bypass Cover Block off Plate Compatible with Ge…
Best forClean LS oil bypass cover
- CNC-machined billet aluminum
- High-temp FKM gasket included
ConsiderBlack finish may scratch
CNRAQR LS Engine Oil Cooler Bypass Cover Block off Plate Compatible with Ge…
Best forLS oil bypass with sensor ports
- Two 1/8 NPT ports
- Improved oil flow design
ConsiderPorts may need sealing
LS Billet Oil Cooler Block off Plate Compatible with Gen III IV Series Engi…
Best forMultiple LS oil cooler deletions
- Two plates for value
- Lightweight 6061-T6 aluminum
ConsiderNot compatible with all pans
RJSPHH LS steam vent coolant crossover ls throttle body Bypass Cylinder Hea…
Best forLS coolant crossover simplification
- Complete pair kit
- Fits all LS engines
ConsiderNo instructions included
Saillong 2 Pack LS Billet Oil Cooler Block-Off Plate, Silver
Best forLS oil cooler bypass backup
- Two plates for spare
- Rust-proof aluminum
ConsiderNo gasket included
Podavelle LS Oil Cooler Bypass Block-Off Plate for Gen III IV Series Engine…
Best forHeavy-duty LS oil bypass
- Thick 1/2-inch aluminum
- Anodized for durability
ConsiderNot for GTO or dry-sump pans
LS Engine Oil Cooler Bypass Cover Block-Off Plate for Gen III/IV LS Engines…
Best forOE replacement LS bypass cover
- Precise OE replacement
- High-strength aluminum
ConsiderNo sensor ports
Artudatech Coolant Block-Off Plate – OEM Fit for Duramax
Brand: Artudatech
A reliable OEM-grade coolant block-off plate for Duramax owners.
The Artudatech coolant block-off plate is precision-crafted to meet OEM standards, ensuring a seamless fit for Chevy and GMC 6.6L Duramax engines from 2001 to 2017. You will appreciate the rigorous testing that goes into each unit, guaranteeing accurate parameters and reliable performance. The premium-grade materials are lightweight and colorfast, so the plate resists corrosion and maintains its appearance over time.
This aftermarket solution delivers excellent value without compromising quality. If you are replacing a failed coolant bypass or upgrading your Duramax cooling system, this plate provides a durable seal that helps prevent leaks and keeps your engine running cool. The included O-ring seal adds an extra layer of protection, making installation straightforward.
- OEM-compatible precision fit
- Lightweight and corrosion-resistant
- Includes O-ring seal
- Limited to Duramax engines
- No hardware included
Saillong LS Billet Oil Cooler Block-Off Plate – Leak Prevention
The Saillong LS billet oil cooler block-off plate is designed to seal the oil pan and prevent leakage during LS engine installation. It is compatible with Gen III and IV series engine models, offering a seamless installation process without requiring modifications. You will find the aluminum alloy construction durable, strong, and rust-proof, ensuring long-lasting performance.
This plate is precision-manufactured to provide a safe and reliable seal, which is essential for maintaining proper oil pressure. Whether you are deleting the oil cooler or simplifying your LS swap, this lightweight plate is an excellent choice. The silver finish adds a clean look to your engine bay while protecting against corrosion.
- Durable aluminum alloy
- Easy bolt-on installation
- Prevents oil leaks
- Single pack only
- No gasket included
Pilida LS Coolant Steam Port Plate Set – Complete Kit
The Pilida LS engine throttle body bypass and coolant steam port plate set is compatible with all LS series engines from 1997 to 2014, including Gen III and IV small block Chevys. This kit is used to cap off the front or rear coolant system air bleed passages in the cylinder heads. You get two O-rings, two bolts, and two coolant port covers, one for each side.
Constructed from 6016 billet aluminum with a natural finish, these plates are anti-rust and durable. The precision machining ensures a perfect seal, helping you eliminate coolant leaks and simplify your cooling system. If you are doing an LS swap or cleaning up your engine bay, this complete set is a convenient solution.
- Complete kit with hardware
- Fits all LS engines
- Anti-rust billet aluminum
- Natural finish may show dirt
- No instructions included
CNRAQR LS Oil Cooler Bypass Cover – No Sensor Ports
Brand: CNRAQR
A precision-machined oil cooler bypass cover with a reliable seal.
The CNRAQR LS oil cooler bypass cover is compatible with most GM Gen III and IV LS-series small block oil pans with oil cooler ports above the oil filter. It serves as an upgraded replacement for the OE GM part number 12577903. The cover is CNC-machined from billet 6061-T6 aluminum and anodized in black, offering excellent strength and corrosion resistance.
This version has no sensor ports, making it ideal for a clean, simple installation. The package includes an upgraded gasket made from high-temp FKM rubber bonded to aluminum, ensuring a leak-free seal, along with two zinc-plated steel flanged hex head mounting screws. You will appreciate the easy installation and reliable performance.
- CNC-machined billet aluminum
- High-temp FKM gasket included
- No sensor ports for simplicity
- Black finish may scratch
- No sensor port option
CNRAQR LS Oil Cooler Bypass Cover – With NPT Ports
This CNRAQR LS oil cooler bypass cover is similar to the no-sensor version but includes two 1/8-inch NPT ports, giving you flexibility for adding sensors or fittings. It fits most GM Gen III and IV LS-series oil pans and replaces OE part 12577903. The billet 6061-T6 aluminum construction is anodized in black for durability and a sleek look.
The large ported internal cavity with smooth features improves oil flow, and the included high-temp FKM rubber-to-aluminum gasket ensures a leak-free seal. Two zinc-plated steel mounting screws are provided for a secure fit. If you need to monitor oil pressure or temperature, these ports are a valuable addition.
- Two 1/8 NPT ports
- Improved oil flow design
- Includes high-temp gasket
- Ports may need sealing
- Slightly more complex install
CNRAQR LS Billet Oil Cooler Block-Off Plate – 2 Pack
The CNRAQR LS billet oil cooler block-off plate comes in a convenient 2-pack, compatible with Gen III and IV series engines including LS3, LSX, LS1, LS2, LS6, and more. It is designed to seal the oil pan and prevent leakage during LS engine installation. The plate is made from lightweight aluminum alloy 6061-T6, providing strong strength and good durability.
This 2-pack is perfect if you have multiple projects or want a spare on hand. The installation is straightforward, with all necessary accessories included. The black anodized finish adds a subtle, professional look to your engine bay while resisting corrosion. Upgrade your LS engine with these reliable block-off plates.
- Two plates for value
- Lightweight 6061-T6 aluminum
- Easy installation with hardware
- Not compatible with all pans
- Black finish may fade
RJSPHH LS Steam Vent Coolant Crossover Plate – Billet Set
The RJSPHH LS steam vent coolant crossover plate simplifies your coolant crossover plumbing by covering the front or rear ports in your cylinder heads. It is compatible with all LS series engines from 1997 to 2014, including LSX, LS1, LS3, LS2, and more. The kit includes everything you need to seal off one pair of ports: two coolant ports, two O-rings, and two bolts.
This billet aluminum set is precision-machined for a perfect fit, helping you eliminate coolant leaks and reduce clutter. The natural finish is clean and durable. If you are building an LS engine and want to streamline your cooling system, this kit is an excellent choice.
- Complete pair kit
- Fits all LS engines
- Billet aluminum construction
- No instructions included
- Natural finish may oxidize
Saillong 2 Pack LS Billet Oil Cooler Block-Off Plate – Silver
The Saillong 2-pack LS billet oil cooler block-off plate offers the same leak-prevention benefits as the single pack but with an extra plate for your toolbox. It is compatible with Gen III and IV series engines, providing a seamless installation process without modifications. The aluminum alloy construction is durable, strong, and rust-proof.
Each plate is precision-manufactured to ensure a safe and reliable seal, helping maintain proper oil pressure. The silver finish is clean and corrosion-resistant. Whether you are working on multiple LS swaps or want a backup, this 2-pack delivers excellent value.
- Two plates for spare
- Rust-proof aluminum
- Precision seal
- No gasket included
- Silver may show scratches
Podavelle LS Oil Cooler Bypass Plate – Heavy Duty 1/2-Inch
The Podavelle LS oil cooler bypass block-off plate is designed to bypass the oil cooler feed and return ports in your oil pan above the oil filter. It is 1/2-inch thick, allowing more oil to flow through the engine internally. The plate is manufactured from lightweight 6061-T6 aluminum with an anodized finish for strength and anti-corrosion.
This plate is compatible with all LS oil pans, except GTO front-sump, dry-sump, and LS4 pans due to internal oil routing differences. The heavy-duty construction ensures a secure seal and long-lasting performance. If you are deleting the oil cooler for a cleaner setup, this plate is a robust choice.
- Thick 1/2-inch aluminum
- Anodized for durability
- Broad LS pan compatibility
- Not for GTO or dry-sump pans
- Single plate only
AWL Brothers LS Oil Cooler Bypass Cover – No Sensor Ports
The AWL Brothers LS engine oil cooler bypass cover is designed to fit Gen III and Gen IV LS engines, providing a precise replacement for the factory oil cooler bypass cover. It replaces OE part number 12577903 with a no-sensor-port design, installing easily without modifications. The high-strength aluminum alloy construction offers excellent durability and corrosion resistance.
Engineered with tight machining tolerances, this cover ensures a secure fit that helps maintain proper oil pressure and prevents leaks. The black anodized finish adds a sleek look. If you want a reliable, straightforward oil cooler bypass solution, this cover is a great pick.
- Precise OE replacement
- High-strength aluminum
- Tight tolerances for leak prevention
- No sensor ports
- No gasket included
Buyer’s Guide: What to Consider
Choosing the right block-off plate involves more than just picking a part. Consider engine compatibility, material quality, and sealing needs. This guide helps you evaluate key factors for a successful installation.
- Compatibility: Ensure the block-off plate matches your engine model and year. For LS engines, check Gen III/IV compatibility and oil pan type. For Duramax, verify the specific engine code and coolant port location.
- Material Quality: Look for plates made from billet aluminum (6061-T6) or similar alloys. These offer strength, corrosion resistance, and lightweight performance. Anodized finishes add extra durability against heat and chemicals.
- Sealing Mechanism: Check if the plate includes a gasket or O-ring. High-temp materials like FKM rubber provide reliable, leak-free seals. Some plates require separate gaskets, so factor that into your purchase.
- Port Options: Decide if you need sensor ports (e.g., 1/8 NPT) for oil pressure or temperature gauges. No-sensor designs are simpler, but ports offer flexibility for monitoring. Choose based on your build requirements.
- Hardware Included: Some kits include bolts and gaskets, while others require separate purchase. Complete kits save time and ensure proper fitment. Verify the thread size and length for your application.
Conclusion
Block-off plates are essential for sealing unused coolant or oil ports, preventing leaks, and maintaining engine performance. From Duramax-specific plates to versatile LS kits, the options above cover a range of needs and budgets.
For most LS builds, the CNRAQR plates offer excellent quality and value, while the Artudatech plate is ideal for Duramax owners. Assess your engine type and port requirements to make the best choice.
Erica Steven is the founder and lead writer of WorstBrands, a site dedicated to providing honest and trustworthy reviews about outdoor gear and fashion products.
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