National 99374 Engine Crankshaft Repair Sleeve - Front or Rear

Engine Crankshaft Repair Sleeve for Rear Seal Repair

National 99374 is a stainless steel engine crankshaft repair sleeve used to restore a worn sealing surface at the rear of the crankshaft. It is sized for a 3.740 in. to 3.746 in. shaft diameter and provides a precise repair surface for rear main seal service on a wide range of Ford, Lexus, Lincoln, Mazda, Mercury, and Toyota applications.

Built for rear crankshaft sealing repairs, this sleeve measures 0.500 in. overall width, 0.344 in. width on shaft, and 1.750 in. installation depth. The flanged outside diameter is 4.031 in., and the stainless steel construction supports a durable sealing surface where crankshaft wear has affected seal performance. This part cross-references Dorman - HELP 99374 for the same application.

Key Features

• Engine crankshaft repair sleeve for rear seal service
• Stainless steel construction for a durable repair surface
• Shaft size: 3.740 in. to 3.746 in.
• Flanged outside diameter: 4.031 in.
• Installation depth: 1.750 in.
• Overall width: 0.500 in.
• Width on shaft: 0.344 in.
• National 99374 for rear crankshaft sealing repairs

Detailed Description

National 99374 is an engine crankshaft repair sleeve designed to restore the sealing area on a worn crankshaft journal. By providing a new stainless steel sealing surface, it helps address rear main seal wear on vehicles such as Ford F-150, Ford Explorer, Lexus GX460, Toyota Tundra, and Lincoln Navigator rear applications. National has supplied sealing solutions for decades, and this part reflects that focus with precise dimensions for service work where crankshaft wear has compromised seal contact.

Compatible With 1981-2019 Ford, Lexus, Lincoln, Mazda, Mercury, and Toyota rear applications listed in the fitment data, including Ford Mustang rear, Toyota Sequoia rear, Lexus LS430 rear, and Mazda CX-9 rear. National 99374 is also referenced by part numbers 99374RS and KWK99374.

What It Helps Repair

• Rear main seal leakage caused by crankshaft wear
• Grooves or scoring on the crankshaft sealing surface
• Oil seepage at the rear of the engine
• Seal contact issues after crankshaft surface damage
• Repeat seal failure from an uneven shaft surface

Installation Notes and Tips

Verify shaft diameter before installation; this sleeve is specified for a 3.740 in. minimum and 3.746 in. maximum shaft size. Confirm the rear crankshaft application and measure the sealing surface carefully so the sleeve seats to the correct installation depth. Clean the shaft thoroughly before fitting the sleeve, and inspect the rear main seal area for wear or damage that could affect sealing performance.

Quality Assurance

National is known for sealing products and has supported the industry for more than 75 years. Part number 99374 is built with stainless steel and dimensioned for service accuracy in rear crankshaft repair applications.