Hose Assembly | Sierra 18-99526

Sierra Hose Assembly | 18-99526 | Outboard Gear Lube Pump | Replaces CDI 551-33HB

The Sierra #18-99526 is a replacement hose assembly for outboard gear lube pump kits. Gear lube pump hose assemblies connect the pump body to the lower unit's gear lube drain or fill port, delivering new gear lube into the lower unit under pump pressure and allowing old lube to be evacuated cleanly. This hose is a direct replacement for CDI 551-33HB. Sierra is one of the most widely distributed marine aftermarket parts brands in North America, producing hoses, pumps, and service accessories engineered to meet OEM performance specifications.

Part Details:

• Part Number: 18-99526
• SKU: SIERRA-18-99526
• Manufacturer: Sierra
• Type: Hose Assembly — Outboard Gear Lube Pump
• Replaces CDI: 551-33HB
• Application: Outboard lower unit gear lube service pump — verify fitment against your pump kit's parts list before ordering
• Condition: New
• Country of Origin: USA

Additional Information

Why Replace a Gear Lube Pump Hose:

Gear lube pump hoses flex and compress with every use and are exposed to gear lube, water, and UV light in outdoor storage. Over time the hose inner liner degrades, the hose walls stiffen or crack, and fittings corrode or develop leaks at the crimp or connection point. A leaking gear lube pump hose makes lower unit service messy and inaccurate — you can't be sure how much lube has been delivered if the hose is losing fluid at a fitting. Replace the hose assembly when:

• The hose shows visible cracking, kinking, or permanent deformation in the wall
• The hose leaks at the pump fitting or the lower unit connection under pump pressure
• The fitting threads are corroded or cross-threaded from previous service
• The hose has stiffened to the point where it will not route cleanly to the drain plug

Outboard Lower Unit Gear Lube Service — Why It Matters:

Lower unit gear lube should be drained and refilled at least annually or every 100 hours on most outboards. The gear lube lubricates the bevel gears, pinion gear, and propeller shaft bearings in the lower unit, and also provides early warning of seal failure: milky or water-contaminated gear lube when draining indicates a failed prop shaft seal, driveshaft seal, or drain plug sealing ring that must be addressed before the lower unit bearings are damaged. A gear lube pump kit with a quality hose assembly makes this service faster and cleaner than the fill-from-below gravity method.

Frequently Asked Questions

1. How do I confirm this hose assembly is compatible with my gear lube pump kit?
Cross-reference Sierra 18-99526 or CDI 551-33HB against your pump kit's parts diagram or the pump manufacturer's replacement parts list. If you are unsure whether this hose fits your specific pump kit, contact us at MacombMarineParts.com with your pump kit model number and we'll confirm before you order.

2. What should I look for when draining outboard gear lube?
When draining the lower unit, collect the old gear lube and inspect it before disposal: clear or dark amber lube is normal; milky, gray, or foamy lube indicates water contamination from a seal failure. Metal particles or a metallic sheen in the old lube indicates bearing or gear wear. Either condition requires further diagnosis and repair beyond a routine lube change before the outboard is returned to service.

3. How often should outboard gear lube be changed?
Most outboard manufacturers specify annual or 100-hour gear lube changes, whichever comes first. Consult your outboard's owner's manual for the recommended service interval for your specific engine. End-of-season gear lube changes before winterization are particularly important — any moisture that has entered the lower unit will cause corrosion damage to bearings and gears if left over the winter in contaminated lube.