Sherwood 29000-Series Raw Water Pump Impeller AN5749

Sherwood 29000-Series Raw Water Pump Impeller — AN5749

Overview

The AN5749 is a 12-blade neoprene flexible impeller for Sherwood 29000-series large raw water cooling pumps. With a 3-3/4-inch (95 mm) outside diameter and an unusually wide 4-inch (102 mm) body on a 10-tooth splined hub, this is one of Sherwood’s largest impeller sizes, designed for the high cooling-water flow requirements of large marine diesel engines. It is sold here as an individual impeller replacement — for the complete service kit including gasket and O-ring, see the Sherwood 29000K Impeller Kit.

Fitment note: Do not select this impeller by engine displacement or brand alone. Confirm that the installed pump specifically calls for a 29000-series Sherwood impeller using a 3-3/4-inch diameter, 4-inch width, and 10-tooth splined hub before ordering.

Compatible Applications

• Sherwood G2902X large raw water pump
• Sherwood G2903X large raw water pump
• Sherwood G2904X large raw water pump
• Select Caterpillar 3406E, C15, and C18 marine engines (via G2902X pump)
• Cross-references to Caterpillar 296-8388, Cummins 4933742, John Deere DZ108622
• All applications: confirm pump model number and impeller dimensions before ordering

Dimensions

• Outside diameter: 3-3/4 in. / 95 mm
• Width: 4 in. / 102 mm
• Hub: 10-tooth spline
• Blades: 12 flexible neoprene vanes

Cross-Reference / Alternate Part Numbers

• AN5749 — SKU as supplied
• Sherwood 29000 — impeller-only reference
• Sherwood 29000K / 762-29000K — complete service kit (impeller + gasket + O-ring)
• Caterpillar 296-8388 / 2968388
• Cummins 4933742
• John Deere DZ108622
• JMP Marine 8359-01K | CEF 500192

Impeller vs. Full Kit

This listing is for the impeller only. If your pump service requires replacement of the gasket and O-ring as well, order the Sherwood 29000K Impeller Kit (762-29000K) which includes the impeller, gasket, O-ring, and service instructions. The kit is the recommended choice when reassembling a pump that has been fully disassembled or has accumulated significant hours.

Service Interval

Inspect the raw water pump impeller at every annual engine service or every 200–300 hours of operation, whichever comes first. On high-output large-engine applications using 29000-series pumps, even partial blade damage significantly reduces cooling water flow. Replace proactively — do not wait for an overheating event.

• Replace when blades are cracked, torn, hardened, or permanently bent
• Replace when any blade fragments are missing — locate and flush all fragments from the cooling circuit
• Replace when the 10-tooth spline hub shows wear or slippage
• Replace after any dry-running event or cooling-system overheating alarm
• Replace after ingestion of sand, silt, or debris
• Replace at the scheduled cooling-system service interval regardless of visual condition

Installation Notes

• Shut down the engine and close the raw-water seacock before beginning
• Remove the pump cover and retrieve the old impeller — use Sherwood’s insert/puller system if available
• Recover all broken blade fragments from the pump body and downstream cooling circuit before fitting the new impeller
• Inspect the pump cam, wear plate, cover, housing, and shaft splines for scoring or damage
• Lubricate the new impeller with glycerine, soapy water, or another approved non-petroleum lubricant before installation
• Align the 10-tooth spline carefully before pressing the impeller onto the shaft
• Replace the pump gasket and O-ring at the same time — see the 29000K kit if these are not on hand
• Reopen the seacock and confirm strong cooling-water flow at the overboard discharge before placing the engine under load
• Never run a flexible impeller pump dry

Related Parts

• Sherwood 29000K Impeller Kit (762-29000K) — Complete Service Kit with Gasket & O-Ring
• Sherwood 18000K Impeller Kit — 14-Tooth Spline Raw Water Pump Service Kit
• Sherwood 26000K Impeller Kit — G2600 Raw Water Pump (10-Tooth, 3-1/8 in. Wide)
• Sherwood 27000K Impeller Kit — P270 Raw Water Pump Service Kit
• Sherwood Water Pump Cam Alignment Pin S21566
• Browse All Impeller Service Kits

Technical FAQ

How do I confirm this is the correct impeller for my pump?

Locate the pump model number on the pump body or in your engine’s parts manual. If the pump is a Sherwood G2902X, G2903X, or G2904X, the 29000-series impeller is the correct fit. Confirm the 3-3/4-inch diameter, 4-inch width, and 10-tooth splined hub against the old impeller or service documentation before ordering.

What is the difference between AN5749 (impeller only) and the 29000K kit?

AN5749 is the impeller alone. The 29000K kit includes the same impeller plus the pump gasket and O-ring. If your gasket and O-ring are in good condition and you are not disassembling the full pump, the impeller only may be sufficient. If the pump has been fully disassembled or the sealing parts are due for replacement, order the complete 29000K kit.

Why does the 29000-series impeller have to be 4 inches wide specifically?

The 4-inch width is what distinguishes the 29000-series from similar Sherwood impellers. The 26000K uses the same 10-tooth spline and 3-3/4-inch diameter but is only 3-1/8 inches wide. Fitting a narrower impeller in a 29000-series pump will reduce cooling water output significantly — confirm the width before ordering.

What happens if impeller blade fragments are not recovered?

Rubber fragments from a broken impeller can lodge in the thermostat housing, heat exchanger passages, or cylinder head cooling galleries. This reduces or blocks cooling water flow and can cause a secondary overheating event even with a new impeller fitted. Flush the cooling circuit thoroughly and inspect the thermostat and heat exchanger after any impeller failure.

Can I reuse the old impeller for another season if it looks okay?

Not recommended on a high-output large-engine cooling system. Neoprene impellers harden and lose flexibility with age, heat cycling, and dry-running exposure. A visually acceptable impeller can fail suddenly under load. Annual replacement is the standard recommendation for commercial and high-hours marine diesel applications.

Parts Desk Insights

Best use case: The AN5749 29000-series impeller is the right choice for large marine diesel engine cooling systems — primarily Caterpillar 3406E, C15, and C18 applications using the Sherwood G2902X pump, and other high-volume cooling installations using the 29000-series pump body. At this price point, customers are typically doing a scheduled service on a commercial vessel, a serious power yacht, or a large workboat where the cooling system demands high-flow and the consequences of an impeller failure are significant. The impeller-only format suits customers who service their own pumps and already have gaskets on hand.

Common customer questions: The most frequent issue is customers confusing the 29000-series with the 26000-series — both use a 10-tooth spline and a 3-3/4-inch outside diameter, but the 29000 is 4 inches wide versus 3-1/8 inches for the 26000. Always confirm the pump model number and impeller width before completing the order. The second common question is whether to order the impeller only or the full 29000K kit — recommend the kit if the pump has been disassembled or if the gasket and O-ring are unknown; recommend the impeller only if the customer is doing a cover-off impeller swap on a pump with known-good seals.