Sierra 18-5250 Ignition Tune-Up Kit for MerCruiser 110/120/140/2.5L/3.0L GM 153/181 L4 Delco Ignition

The Sierra 18-5250 Ignition Tune-Up Kit is a complete ignition service kit built for GM in-line 4 and 6 cylinder marine engines running a conventional Delco contact-point ignition system with standard rotation (it is not compatible with Thunderbolt ignition systems). It is precision-built to meet or exceed the original equipment components it replaces, giving boat owners a straightforward way to restore reliable spark and smooth running during a scheduled tune-up.

The kit is sized for MerCruiser 110, 120, and 140 I/O models powered by the GM 153 cid and 181 cid L4 engines, as well as the 2.5L and 3.0L L4 models that continued to use the contact-point ignition into the late 1980s. Coverage spans specific serial number ranges for each model, so matching the engine's serial number to the correct application ensures the kit's components are the right fit before installation. The components carry a machined exterior finish for durability in a marine engine bay environment.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-5250
• Product Dimensions: 6 x 2.75 x 1.75 inches
• Weight: 0.14 pounds
• Exterior Finish: Machined
• Ignition System Compatibility: Conventional Delco ignition, standard rotation (excludes Thunderbolt ignition)
• UPC: 030999256256
• OEM Cross Reference: GLM 72610, Evinrude/Johnson 172527, Mallory 9-29300, Mercruiser 34235T1, Mercruiser 34235Q1, OMC 175257, OMC 172527

Fitment

• MerCruiser 110 (153 cid GM L4), 1963-1966, Serial 1537370-2044033
• MerCruiser 120 (153 cid GM L4), 1964-1986, Serial 1666601-B531853
• MerCruiser 2.5L (153 cid GM L4), 1987-1989, Serial B531854-C853255
• MerCruiser 140 (181 cid GM L4), 1968-1986, Serial 2508261-B450800
• MerCruiser 3.0L (181 cid GM L4), 1987-1989, Serial B450801-C856558

Replaces (OEM)

• GLM 72610
• Evinrude/Johnson 172527
• Mallory 9-29300
• Mercruiser 34235T1
• Mercruiser 34235Q1
• OMC 175257
• OMC 172527

Frequently Asked Questions

What engines does the Sierra 18-5250 tune-up kit fit? The Sierra 18-5250 fits GM in-line 4 cylinder marine engines with a conventional Delco contact-point ignition system, standard rotation, including MerCruiser 110 and 120 (153 cid L4), MerCruiser 140 (181 cid L4), and the 2.5L and 3.0L L4 models within their listed serial number ranges.

Will the 18-5250 work with a Thunderbolt ignition system? No. The Sierra 18-5250 is designed for conventional Delco contact-point ignitions with standard rotation and specifically excludes engines equipped with Thunderbolt ignition.

How much does the 18-5250 tune-up kit weigh? The Sierra 18-5250 tune-up kit weighs 0.14 pounds.

What are the dimensions of the 18-5250 kit packaging? The Sierra 18-5250 measures 6 x 2.75 x 1.75 inches.

Is the Sierra 18-5250 an OEM part or aftermarket? It is an aftermarket kit manufactured by Sierra, built to meet or exceed the specifications of the original equipment ignition components it replaces.

Which OEM part numbers does the 18-5250 cross-reference to? The Sierra 18-5250 is interchangeable with GLM 72610, Evinrude/Johnson 172527, Mallory 9-29300, Mercruiser 34235T1, Mercruiser 34235Q1, and OMC 175257/172527.

Does the 18-5250 fit a MerCruiser 3.0L engine? Yes, MerCruiser 3.0L models (181 cid GM L4) built between 1987 and 1989, serial numbers B450801 through C856558, use the Sierra 18-5250 tune-up kit.

Does the 18-5250 fit a MerCruiser 2.5L engine? Yes, the MerCruiser 2.5L (153 cid GM L4) built between 1987 and 1989, serial numbers B531854 through C853255, uses the Sierra 18-5250 tune-up kit.

How do I know if the 18-5250 fits my specific MerCruiser engine? Match your engine's serial number to the ranges listed for your model: MerCruiser 110 (1537370-2044033), 120 (1666601-B531853), 140 (2508261-B450800), 2.5L (B531854-C853255), or 3.0L (B450801-C856558), all covered by the Sierra 18-5250.

What finish do the components in the 18-5250 kit have? The components in the Sierra 18-5250 tune-up kit have a machined exterior finish.

Is the Sierra 18-5250 covered under warranty? Yes, the Sierra 18-5250 is covered under Sierra's standard customer satisfaction warranty, the same warranty applied across Sierra's marine parts line.