Sierra 18-1937 Exhaust Elbow for Mercruiser 3.7L Engines with Aluminum Exhaust Manifolds

The Sierra 18-1937 is an exhaust elbow built for Mercruiser 3.7L (224 cid) 4-cylinder sterndrive engines equipped with aluminum exhaust manifolds. The elbow routes exhaust gases and cooling water away from the manifold and out through the exhaust system, and it is manufactured as a direct OE replacement that is fully interchangeable with the original equipment part it replaces. It is primed and painted in grey for added durability and corrosion protection, and it arrives ready to install out of the box without additional machining or fitting.

This elbow is designed specifically for engines fitted with aluminum exhaust manifolds rather than cast iron manifolds, so confirming manifold material before ordering ensures correct fitment. It fits 3.7L engines rated at 170 HP for the 1985-1986 model years within serial number range 6916779 to B434940, as well as 3.7L engines rated at 180 HP for 1987 within serial number range B436391 to B775248. Always verify your engine's serial number against these ranges before purchase.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-1937
• Product Type: Exhaust Elbow
• Category: Mercruiser Exhaust Manifolds
• Compatible Engine: 3.7L (224 cid) 4-cylinder Mercruiser engines
• Exhaust Manifold Type: Aluminum
• Fitment (170 HP): 1985-1986, serial numbers 6916779 to B434940
• Fitment (180 HP): 1987, serial numbers B436391 to B775248
• Color: Grey
• Finish: Primed and painted
• Package Dimensions: 20 inches x 9 inches x 7 inches
• Weight: 34.53 pounds
• UPC: 808282126766

Fitment

• 3.7L (224 cid) engine, 170 HP, 1985-1986, serial numbers 6916779 to B434940, aluminum exhaust manifolds
• 3.7L (224 cid) engine, 180 HP, 1987, serial numbers B436391 to B775248, aluminum exhaust manifolds

Frequently Asked Questions

What engines does the Sierra 18-1937 exhaust elbow fit? The Sierra 18-1937 fits Mercruiser 3.7L (224 cid) 4-cylinder engines equipped with aluminum exhaust manifolds, covering 170 HP engines from 1985-1986 (serial numbers 6916779 to B434940) and 180 HP engines from 1987 (serial numbers B436391 to B775248).

Does the 18-1937 elbow work with cast iron exhaust manifolds? No, the 18-1937 elbow is designated for engines with aluminum exhaust manifolds; a separate part number applies to the cast iron manifold version, so confirm your manifold material before ordering.

How do I confirm my engine matches this part? Check your Mercruiser 3.7L engine's serial number against the ranges listed for the 18-1937 elbow: 6916779-B434940 for the 170 HP 1985-1986 application, or B436391-B775248 for the 180 HP 1987 application.

Is the Sierra 18-1937 a direct OEM replacement? Yes, the 18-1937 elbow is manufactured as a direct OE replacement and is fully interchangeable with the original equipment elbow it replaces.

What color and finish does the 18-1937 elbow have? This exhaust elbow is grey and comes primed and painted for added durability and corrosion protection.

How much does the 18-1937 exhaust elbow weigh? The Sierra 18-1937 exhaust elbow weighs 34.53 pounds.

What are the package dimensions for the 18-1937 elbow? It ships in a package measuring 20 inches x 9 inches x 7 inches.

Is installation straightforward for this elbow? The Sierra 18-1937 arrives ready to install out of the box, with no additional fitting required before mounting to a compatible 3.7L Mercruiser engine.

What is included when I order part number 18-1937? Ordering the 18-1937 includes one exhaust elbow; no gasket or additional hardware is specified with this part.

Will the 18-1937 fit a 3.7L engine outside the listed serial number ranges? Fitment for the Sierra 18-1937 is specific to the 170 HP 1985-1986 range (6916779-B434940) and the 180 HP 1987 range (B436391-B775248); engines outside these ranges should be verified before purchase.